Abstract in English:

ABSTRACT This research investigates to remove and strengthen the weak smeared mortar and enhance its quality through sustainable and eco-friendly treatment techniques. The impregnation of recycled coarse aggregate (RCA) in acids (ATRCA) in different molarities was proposed to eradicate the weak smeared cement particle on the RCA and impregnation of RCA in slurries (STRCA) at various dosages was proposed to strengthen the weak smeared mortar on the RCA. The properties of the RCA were assessed prior and after treatment techniques. The micro-structure of the treated RCA was examined through SEM to assess the impact of treatment techniques on the RCA properties. Results infer that both treatments tend to improve the quality of RCA, however slurry treatment strengthens the weak mortar rather than its removal through acid treatment and thus resulting in better properties to RCA. The optimized molarity was observed at 0.3 M for 3 days for acid treatment and optimized slurry dosage was observed at 0.8w/c ratio for 24 hours. The optimized ATRCA and STRCA show 21.70% and 39.07% lesser water absorption than RCA. Similarly, other physical and mechanical properties of ATRCA and STRCA were enhanced compared to RCA. Correlation was established between physical and mechanical properties of the RCA, ATRCA and STRCA. Life cycle assessment of the aggregates was performed with OpenLCA software.

Abstract in English:

ABSTRACT This study investigates the use of waste plastic (polyethylene and polypropylene) and foundry sand to manufacture eco-friendly paver blocks, providing a sustainable alternative to conventional materials. The project aims to address the challenges of plastic waste disposal and environmental damage caused by sand mining. Twelve paver block samples were prepared with varying proportions of plastic (30%–60%) and foundry sand, with or without coarse aggregate. The mechanical properties, including compressive strength, flexural strength, water absorption, and fire resistance, were tested following ASTM standards. The optimal mix, FPA-2 (40% plastic, 40% foundry sand, 20% coarse aggregate), exhibited a compressive strength of 27 N/mm2 and a flexural strength of 6.7 N/mm2, comparable to traditional paver blocks. Water absorption rates were below 7%, and the blocks met fire resistance criteria. Cost analysis revealed that plastic-based paver blocks are up to 25% cheaper than conventional ones, enhancing their economic feasibility. By repurposing waste materials, this study offers a sustainable solution for reducing natural resource dependency and mitigating environmental harm. The findings highlight the potential for plastic-based paver blocks to promote circular economy practices, maintain performance standards, and provide cost-effective alternatives for the construction industry.

Abstract in English:

ABSTRACT This study explores the impact of nano-TiO2 additives on sealing materials for methane drainage boreholes in coal mines. Varying nano-TiO2 contents (0.5%, 1.0%, 1.5%, and 2.0%) were investigated, with 1.5% emerging as the optimal dosage. At this concentration, early-age strength increased by 28.6% at 3 days, while gas permeability decreased by 77.6% compared to the control mixture. The modified sealant exhibited accelerated setting, with initial setting time reduced from 195 to 152 minutes. Fluidity decreased with increasing nano-TiO2 content, necessitating superplasticizer adjustment. Microstructural analysis revealed a 34.2% reduction in total porosity and a refined pore structure. The enhanced performance is attributed to the nanoparticles’ nucleation effect, pore-filling capacity, and participation in pozzolanic reactions. These findings suggest that nano-TiO2-modified sealing materials can significantly improve methane drainage efficiency and mine safety by enhancing borehole airtightness. The study provides valuable insights for developing advanced sealing materials tailored for coal mine applications.

Abstract in English:

ABSTRACT The Zirconium Di- Boride (ZrB2) reinforced AZ64 magnesium metal matrix composite’s (MMMCs) tribological performance was studied for potential use in engineering applications. The composite was developed using the stir-casting method with the help of ultrasonic vibrations for mixing molten AZ64 and preheated ZrB2 particles as it achieves uniform dispersion and better wettability. The physical characteristics was studied through density measurement and the result showed that 3% ZrB2 reinforced composites had an increase in 1.275% of density when related to 0% reinforced MMMCs. The absorbed energy values from charpys impact test of reinforced composites showed an increase of around 85% from the as-cast alloy. The micro hardness of the ZrB2 particles reinforced composite was significantly improved after ultrasonic dispersion. From XRD and EDX it is evident that inclusion of the ZrB2 increased beta-phase precipitation in the Mg alloy, which in turn enhances the strength of the composites. Sliding wear tests were conducted in dry conditions utilizing pin-on-disc (POD) tribometer at standard loads (20–60N) and speeds (1.2–2.4 m/s). Improved wear resistance was seen in the 3% ZrB2 reinforced composites as a result of its finer grain and relatively uniform distribution of ZrB2 particles. Increasing the load resulted in a higher wear rate of the composite at all sliding speeds. Increased capacity of the reinforcement and other characteristics of the produced composite proved to be superior to the AZ64 as cast alloy in all wear test situations.

Abstract in English:

ABSTRACT This study investigates the spray characteristics of non-edible oils, specifically Rapeseed, Jatropha, Neem, and Coconut oils, in Minimum Quantity Lubrication (MQL) systems using Computational Fluid Dynamics (CFD) simulations. The objective was to analyze the effects of MQL parameters—such as inlet air pressure, flow rate, and nozzle diameter—and fluid properties on droplet velocity and diameter. A Discrete Phase Model (DPM) was employed within the CFD framework to simulate the atomization process. Results indicated that increased inlet pressure significantly reduced droplet diameter, with a maximum reduction of 68.35% observed in Coconut oil. Similarly, an increase in flow rate and nozzle diameter led to higher droplet velocities, with the maximum velocity reaching 238.59% of its initial value in Jatropha oil at 6 bar pressure. Viscosity was identified as the most influential fluid property on droplet size, demonstrating a direct relationship with increased droplet diameter. The findings highlight the importance of optimizing MQL parameters and fluid properties to enhance machining performance and reduce environmental impact.

Abstract in English:

ABSTRACT The advancement of nano engineering technology plays a major role in the cementitious materials especially graphene oxide which got high attention. In this research the addition of graphene oxide, silica fume and flyash with various mix proposition in partial replacement of cement have be investigated for mechanical properties of concrete which is the macro level (workability, strength behavior, flexural behavior, water absorption, porosity, and durability) and micro level structural analysis (SEM analysis). Polycarboxylate ethers are used as super plasticizers to offset this decrease, which substantially improves the concrete’s workability. Silica fume and fly ash are utilized in fixed proposition of 10% of silica fume and 10% of fly ash, by weight, to enhance the strength of concrete. After conducting various tests, it has been determined that the optimal combination involves a 10% replacement of both silica fume and fly ash for ordinary Portland cement, particularly grade 53, resulting in superior outcomes. Addition to its varying percentages from 0, 0.01, 0.02, 0.03, 0.04 and 0.05% of Graphene oxide used to find the optimum percentage of GO by weight of ordinary Portland cement to obtain high strength. The optimum percentage of grapheme oxide to be replaced with cement is 0.04%.

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ABSTRACT This study explores the fastening behavior of punctured double-double (DD) laminates, a superior alternative to traditional quadaxial laminates (QUAD) due to improved structural efficiency and lower maintenance. However, the effect of various cutout shapes and sizes on DD laminates’ fastening performance is still unexplored. This research examines optimal ply orientations, rotation angles, and fastening loads for DD laminates with circular, elliptical, and combined-shape cutouts to assess their impact on stability. A hybrid optimization method using an artificial neural network (ANN) and genetic algorithm (GA) is developed to predict maximum buckling loads, avoiding time-intensive finite element analysis (FEA). The ANN models, with R2 values of 0.994 to 0.999, show excellent performance. The best model for circular cutouts achieved R2 is 0.999 with a mean absolute error of 0.0059. Results indicate that elliptical and combined-shape cutouts significantly influence ply angles and buckling loads. Combined-shape cutouts offer superior stability as size increases, with buckling load improvements of 15% over circular cutouts. This study highlights the potential of ANN-GA techniques for optimizing DD laminate designs and improving structural performance.

Abstract in English:

ABSTRACT Predicting the adhesive force between steel reinforcement and concrete is crucial as it influences stress distribution and the overall mechanical behavior of reinforced concrete. This study proposes a novel approach to enhance bond strength prediction using machine learning (ML) models optimized through Bayesian optimization (BO). A dataset comprising 401 beam tests with six key factors was used to train three distinct ML algorithms—Support Vector Regression (SVR), Random Forest (RF), and Extreme Gradient Boosting (XGBoost). The prediction models were first trained on the full dataset, with BO applied to fine-tune hyperparameters and improve accuracy. Among these models, the BO-XGBoost achieved the best performance, with an R2 of 0.74, MAE of 1.412 MPa, and RMSE of 1.516 MPa on the test set, and R2 = 0.80, MAE = 0.950 MPa, RMSE = 1.200 MPa on the training set. In addition, a simplified model was developed, incorporating only three critical variables—rebar thickness, reinforcement tensile strength, and concrete compressive capacity—to make the model more applicable in real-world engineering scenarios. To further interpret the model’s predictions, Shapley additive explanations (SHAP) were employed, revealing the specific influence of each variable on bond strength. This study demonstrates that the integration of ML with Bayesian optimization can significantly improve the accuracy of bond strength predictions, offering valuable insights for structural design optimization.

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ABSTRACT Sustainable pavement construction is essential for promoting ecological balance and reducing the environmental impact of infrastructure projects. This study investigates the viability of partially replacing conventional fine aggregate (river sand) with steel slag in proportions ranging from 10% to 100% by volume for pavement quality concrete (PQC). The mechanical properties of PQC were evaluated following IRC standards, with a focus on compressive strength, flexural strength, split tensile strength, and fatigue performance. Additionally, the study assessed the concrete’s abrasion resistance and skid resistance, critical for ensuring durability and road safety. The experimental results demonstrated that incorporating steel slag as a fine aggregate replacement significantly enhances the mechanical performance of PQC. A mix containing 40% steel slag exhibited optimal improvements in compressive, flexural, and tensile strengths, alongside superior resistance to wear and skid. These findings indicate that steel slag, when used in appropriate proportions, can enhance both the durability and safety of concrete pavements. The study highlights the potential of steel slag as a sustainable and resource-efficient alternative to conventional materials in pavement construction, contributing to environmental sustainability and improved infrastructure performance.

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ABSTRACT The study explores the perforating shear performance of Fiber-Reinforced Polymer (FRP) concrete blocks using machine learning techniques like Gradient-Boosted Regression Trees (GBRT), k-nearest Neighbours (KNN), and Lasso Regression. It aims to predict the structural integrity of FRP blocks under shear conditions based on experimental data. The models were assessed using Coefficient of Determination (R2), Root Mean Square Error (RMSE), and Mean Absolute Error (MAE). GBRT demonstrated superior performance during training with an R2 of 0.9786, RMSE of 52.75, and MAE of 34.12, indicating strong predictive accuracy and minimal error. It outperformed KNN (R2 = 0.92, RMSE = 83.91, MAE = 45.71) and Lasso Regression (R2 = 0.71, RMSE = 162.45, MAE = 115.83). In validation, GBRT again excelled with an R2 of 0.93, RMSE of 76.23, and MAE of 58.46, confirming its robustness in generalizing unseen data. KNN showed lower performance in validation (R2 = 0.86), with increased error values, while Lasso lagged further behind (R2 = 0.681, RMSE = 185.23, MAE = 138.34). GBRT consistently outperformed traditional regression methods, highlighting its potential for more accurate and reliable structural analysis in FRP concrete slabs.

Abstract in English:

ABSTRACT Double-skinned steel-concrete composite columns are famous nowadays in the construction industry because of their structural advantages. The analysis of the performance of double-skinned composite columns with two steel skins of the outer and inner tube, in addition to an in-built steel core in-filled with concrete, was attempted. Steel skins can serve multiple functions, notably defining the geometry of the concrete column and preventing cracks from tensile pressure. This article consists of the research work, numerical and experimental investigation, of the behaviour of Double-Skinned Square Composite Columns (DSSCC) with square cores in-filled with concrete under axial compressive load. The square steel tubes are of size 150 and 50 mm with 6 and 3 mm thickness of outer and inner tubes, respectively, and a height of 500 mm characterized by an inner core of 1 mm thickness. The steel tube considered in the current numerical study (using Abaqus 6.14) is of grade Fe250, Fe350 and Fe415, and in-filled concrete is of grade M20, M25, M30, M35, M40 and M45. The steel tube considered in the present experimental study is of grade Fe250, in addition to the steel cores, which are made of grade A1008 cold-formed steel. The average compressive strength of the concrete used in an experimental study, after 28 days of curing, is measured as 26.07, 32.89 and 40.29 N/mm2. The current study was performed to find the axial compressive behaviour, ultimate load, load versus vertical and horizontal deflection behaviour and corresponding stress and strain value and failure modes. Stiffness, ductility ratio and energy absorption capacity were determined from the observed test values. The results show that increasing concrete compressive strength improves the load-carrying capacity of the column. The experimental and numerical results were discussed and validated.

Abstract in English:

ABSTRACT Worn-out or used abrasive particles from abrasive water jet machining are found to be wasted without recycling in most cases, as they contain different metal and non-metal particles with respect to their application. The abrasive waste obtained from abrasive water jet machining can be gainfully utilized in various engineering applications. Owing to the same, the present work attempts to recycle and reuse the same for manufacturing kenaf fiber-reinforced hybrid polymer composites. Polymer composites were synthesized using the hand lay-up method, incorporating kenaf natural fibers, epoxy resin, and recycled spent abrasive particles. The spent abrasive particles collected from abrasive water jet machining were chosen as the filler material, and they were mixed in different weight percentages with epoxy resin to fabricate a kenaf fiber-reinforced hybrid polymer composite. The effects of recycled spent abrasive particle filler addition on the tensile, flexural, and impact behaviour of the synthesized polymer hybrid composites were examined. Fractured samples with different filler compositions were examined using a scanning electron microscope to probe the failure patterns. The experimental results revealed positive trends in the enhancement of mechanical properties with the inclusion of the spent abrasive particles.

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ABSTRACT Carbon nanotube (CNT)-based sensors are revolutionizing human motion detection through their unique combination of flexibility, sensitivity, and durability. This review examines the transformative impact of these sensors across healthcare, sports science, and wearable technology. Recent breakthroughs in hierarchical sensor architectures and hybrid materials have achieved unprecedented performance, with sensitivity exceeding conventional sensors by orders of magnitude and response times in milliseconds. These advances have enabled applications ranging from rehabilitation monitoring to high-precision athletic performance analysis. The integration of artificial intelligence with CNT sensors is opening new possibilities in personalized healthcare and human-machine interfaces. While challenges remain in manufacturing scalability and long-term stability, emerging developments in self-powered systems and biocompatible designs point toward widespread adoption in next-generation wearable devices. This review synthesizes current progress and identifies promising directions for future innovation in CNT-based motion sensing technology, highlighting its potential to transform how we monitor and understand human movement.

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ABSTRACT This study investigates the optimization of Wire-Cut Electrical Discharge Machining (WEDM) for 2304 duplex stainless steel, a material valued for its superior mechanical properties and corrosion resistance in challenging environments such as oil and gas, marine, and chemical industries. The study aims to evaluate how WEDM parameters—pulse duration, peak current, and wire speed—affect MRR, surface roughness (Ra), and tool wear. Using a Taguchi-based design of experiments (DoE) method, machining trials were conducted by varying these parameters. Results showed that Material Removal Rate (MRR) and surface roughness increased with longer pulse durations and higher peak currents, demonstrating a direct relationship. MRR peaked at 8.8 mm3/s at 300 µs pulse duration and 30 A peak current, while surface roughness increased to 2.1 µm under the same conditions. ANOVA analysis confirmed that pulse duration had the most significant effect on MRR and surface roughness, accounting for 58% and 54% of the variation, respectively. Tool wear, which increased with higher discharge energies, was mainly influenced by peak current, contributing to 45% of the observed variance. This study concludes that optimizing WEDM parameters can enhance machining performance while balancing MRR, surface finish, and tool wear trade-offs.

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ABSTRACT This study investigates the treatment of Sago Wastewater (SW) using natural materials and α-Al2O3 ceramic membranes for filtration. SW samples were collected from influent and effluent of sago industries in Salem and Namakkal districts, Tamil Nadu, as well as from nearby open wells and bore wells. The physico-chemical parameters, including pH, color, turbidity, TSS, TDS, TS, DO, COD, and BOD, were analyzed. High levels of BOD (1800–1550 mg/L) and COD (3400–4150 mg/L) were observed, reflecting the high organic content of the effluents. Post-filtration, pH values ranged from 6.9 to 7.3, with BOD and COD levels within permissible limits set by TNPCB. Toxic substances were reduced by 52% to 96%. Statistical analysis using multiple linear regression showed an R2 of 0.98 in the predicted phase and 0.9 in the treatment phase, while CNN analysis yielded an R2 of 0.99 with an MSE of 5.9 after 2000 epochs. The filtration process significantly reduces toxins, making the treated water suitable for irrigation purposes.

Abstract in English:

ABSTRACT When used as a surface layer on permeable pavements, pervious concrete promotes water percolation, thus helping urban water runoff management. Water percolation occurs due to its porous structure, and interconnected pores are fundamental for its efficiency. To better understand pervious concrete, this study aimed to analyse the porous structure and mechanical and hydraulic properties of pervious concrete. Compressive strength, flexural tensile strength, porosity and permeability coefficient tests were performed. The porous structure was characterised using three approaches: ImageJ software, Sketchup software and scanning electron microscopy. According to hardened state results and Brazilian technical standards, pervious concrete can be used cast-in-place for pedestrian traffic or light vehicular traffic areas. Pervious concrete pores’ length, perimeter, Feret’s diameter and width increase, while circularity and the number of pores decrease as the void volume increases, indicating that as the volume of voids in pervious concrete increases, the pores become larger, more elongated and smaller in quantity. Good to excellent correlations were found between the concrete’s compressive strength, flexural tensile strength and permeability coefficient and the concrete’s porosity, pore area, pore volume and geometric tortuosity, although different image analysis methodologies were used to obtain the porous structure data.

Abstract in English:

ABSTRACT Research has been conducted regarding the influence of Si3N4 micro-particle reinforcement with alloy on the mechanical and wear properties of AZ61/Si3N4 composites. The stir casting technique has been used to create AZ61/Si3N4 composites. Particles of Si3N4 with sizes between 15 to 40 μm and weight percentages of 4, 8, and 12 were mechanically injected into molten AZ61 alloy in an argon gas atmosphere and stirred at 400 rpm. Hardness and impact were shown to be increased gradually with the addition of 4wt.%–12wt.% Si3N4 reinforcement to the composites. Experiments were carried out using a Pin-on Disc tribometer at ambient temperature to simulate the wear rate. To enhance the predictability of wear rate and streamline the tests, a 3-level CCD utilizing RSM was devised. The created model accurately predicted the wear rate with a 95% level of confidence, and its overall validity was confirmed using analysis of variance.

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ABSTRACT This study presents the development and validation of a new electrochemical method for measuring electrolyte density and assessing stratification in lead-acid batteries. The proposed methodology is based on the potential difference between two electrodes, one composed of PbO2 and the other of Pb, both prepared and characterized through cyclic voltammetry. The formation and morphology of the electrodes were confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), revealing characteristic three-dimensional structures. Tests with electrolyte solutions of known density demonstrated an excellent correlation between the measured potential difference and the actual electrolyte density, with an accuracy of ±0.001 g/cm3 compared to measurements made with a portable digital densitometer. The practical application of the method in lead-acid batteries, conducted on a 60Ah commercial battery, validated the proposed technique, showing significant correlation with data obtained from commercial equipment. The study highlights that electrolyte stratification is a critical issue in lead-acid batteries, and the developed method provides an effective and low-cost tool for monitoring this phenomenon. The technique can be applied in various research efforts to improve the performance and durability of lead-acid batteries.

Abstract in English:

ABSTRACT This study presents the development and validation of a new electrochemical method for measuring electrolyte density and assessing stratification in lead-acid batteries. The proposed methodology is based on the potential difference between two electrodes, one composed of PbO2 and the other of Pb, both prepared and characterized through cyclic voltammetry. The formation and morphology of the electrodes were confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), revealing characteristic three-dimensional structures. Tests with electrolyte solutions of known density demonstrated an excellent correlation between the measured potential difference and the actual electrolyte density, with an accuracy of ±0.001 g/cm3 compared to measurements made with a portable digital densitometer. The practical application of the method in lead-acid batteries, conducted on a 60Ah commercial battery, validated the proposed technique, showing significant correlation with data obtained from commercial equipment. The study highlights that electrolyte stratification is a critical issue in lead-acid batteries, and the developed method provides an effective and low-cost tool for monitoring this phenomenon. The technique can be applied in various research efforts to improve the performance and durability of lead-acid batteries.

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ABSTRACT This study employs machine learning (ML) to analyze the melting and reconsolidation behaviors of iron, emphasizing the influence of cold reduction ratios and rolling sequences. Five samples with varied cold reduction ratios and rolling patterns were examined. Findings indicate that when the cold reduction ratio exceeds 65%, coordinated cold melting minimally impacts crystallographic consistency. Texture formation remains largely unaffected during cold melting and short-duration annealing. However, extended annealing prompts irregular grain growth, altering crystal orientation. Sheets rolled in alignment with their initial condition exhibit consistency patterns similar to conventionally cold-melted pure iron after prolonged annealing. Key parameters influencing material performance were evaluated, revealing annealing temperature as the most significant factor (5.94), followed by cold melting direction order (1.46), while the hanging period during annealing had minimal impact (1.02). ML models were employed to predict Goss angle expansion using cold-rolling and annealing parameters. This approach demonstrates the potential of ML to predict texture evolution in pure iron, offering valuable insights for optimizing industrial cold-rolling practices.

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ABSTRACT This experimental study investigates the axial compression effect of rectangular pultruded glass fiber-reinforced polymer (P-GFRP) tubular column sections, examining the impact of width-to-thickness ratio (B/t), aspect ratio (H/B), and column height on their structural performance. A total of 27 GFRP columns were subjected to axial compression tests to evaluate their ultimate load and initial stiffness. The columns exhibited a uniform failure pattern, characterized by crushing, mid-section fractures, and longitudinal splitting at the corners. The results revealed a negative correlation between the ultimate load and the aspect ratio, as well as the width-to-thickness ratio. This study utilized advanced machine learning algorithms, namely Response Surface Methodology (RSM) and Artificial Neural Network (ANN), to develop predictive models for the ultimate load of GFRP columns. The RSM model achieved an R2 value of 0.8347, demonstrating good accuracy in predicting ultimate load. The ANN model outperformed the RSM model, with an R criterion exceeding 0.68807 across training, testing, and validation phases, showing a stronger correlation between experimental and predicted outcomes. This research establishes a framework for forecasting the mechanical properties of column sections.

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Abstract Increased electricity demand in urban and rural areas necessitates renewable energy solutions such as wind power, which is sustainable and non-polluting. However, low wind velocity regions face challenges in adopting small horizontal axis wind turbines (SHAWTs) due to the limited performance and designs under low Reynolds numbers. This study addresses the need for optimized airfoil solutions to enhance SHAWT efficiency under these conditions. The research focuses on the development and analysis of a novel airfoil material, VIT7510, specifically tailored for low wind speeds. Advanced tools such as QBlade software, incorporating XFOIL solvers and Blade Element Momentum (BEM) theory, were utilized to evaluate the aerodynamic properties of the material in terms of lift-to-drag ratio (CL/CD), power coefficient (Cp), and efficiency. Key findings demonstrate that the VIT7510 achieves a maximum CL/CD ratio of 122.89 at an angle of attack of 4.9° and a power coefficient of 0.550 at a tip speed ratio of 4.9. The material outperformed 25 other airfoils, including those from NACA, Selig-Donovan, and Eppler families, under low wind conditions. These results highlight the potential of the VIT7510 material in SHAWT applications, offering a robust solution for energy generation in low-wind regions.

Abstract in English:

ABSTRACT In recent days the natural fiber reinforced polymer composites getting more attention due to their eco-friendly and reliability in many parts of the industries. The lignocellulosic content in natural fibers influenced to use in corrosion and thermal free applications. The hybrid fiber reinforced composites additionally provides the combination of material properties together, the orientation of fiber reflects in strength of the composites as it acting as load bearing factor of the fiber reinforced composites. So, the present work investigates the effect of hybridization and stacking sequence on various material properties such as density, moisture intake by the material, tensile, impact, hardness and thermal stability. The structural characteristics of the fabricated composites is analyzed through Scanning Electron Microscope. The results concludes that the hybridization of glass fiber mat with cellulose fibers mat such as Pineapple Leaf fiber (PALF) and areca fiber depicts the more acceptable bonding relationship with the matrix thus results in improved properties. The fabricated new set of natural and glass reinforced polymer composites have found the tensile strength between 40–65 MPa, Young’s modulus in the range 950–1400 MPa, Impact strength of about 130–190 KJ/mm2 and thermal stability up to 340–390 °C which is higher than the earlier studies reported.

Abstract in English:

ABSTRACT Cementitious Green Hybrid Concrete (CGHC) is gaining recognition as a sustainable choice for low-volume roads, providing environmental benefits and improved mechanical strength over traditional concrete. CGHC reduces traditional cement demand, thus lowering carbon emissions, while its durability minimizes repair needs, extending structural lifespan and reducing resource consumption. This study employs Response Surface Methodology (RSM) with a Central Composite Design (CCD) to analyze the influence of varying proportions of cement, fine aggregate, and coarse aggregate on CGHC's compressive and flexural strengths. The investigation evaluates the impact of coconut shell (COS), lime powder (LP), and rice husk ash (RHA) as partial replacements—substituting COS for coarse aggregate, RHA for fine aggregate, and LP for cement across twenty M30 grade concrete mixes. Results show that RHA and LP replacements generally enhance strength, with RHA substitution at 20% for fine aggregate yielding optimal strength. In contrast, increased COS content reduces strength. This research demonstrates RSM's effectiveness in optimizing CGHC properties, underscoring its potential for eco-friendly road applications.

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ABSTRACT The Cost of Quality (COQ) is widely recognized in manufacturing as a critical performance metric, yet its application in the construction industry remains less established due to fundamental differences in characteristics and environments. While integrating COQ into the planning and building phases of construction projects appears straightforward in theory, practical implementation proves challenging. This study investigates the impact of COQ elements on total quality costs, analyzing 16 building projects using factorial design techniques. Internal and external failure costs emerged as significant factors affecting overall quality, with variations in prevention, appraisal, and failure costs emphasizing the critical role of preventive measures in minimizing quality-related expenses. Statistical hypothesis testing confirmed the substantial influence of failure costs on total quality costs, with Yate’s algorithm and 24 factorial design experiments offering deeper insights into factor effects. The findings underscore the importance of strategic preventive actions, providing valuable implications for enhancing quality management practices, reducing failure costs, and improving overall project efficiency in the construction sector.

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ABSTRACT In order to improve the removal of methylene blue dye from water, zinc oxide nanoparticles (ZnO NPs) were synthesized utilizing Annona squamosa leaf extract as a green reducing agent. Particle size analysis (PSA), FT-IR, XRD, FE-SEM, and EDX) were among the methods used to characterize the ZnO NPs. Following batch adsorption tests, the effectiveness of these nanoparticles in removing dye was evaluated. Many factors were carefully examined, including pH, temperature, initial dye focus, and adsorbent dosage. The outcomes demonstrated a strong agreement between the second-order kinetics of the process of adsorption and the Langmuir isotherm model. The process is exothermic, according to thermodynamic study, which also estimated important parameters like ΔH°, ΔS°, and ΔG°. The dye removal effectiveness reached up to 99% under ideal conditions, which included a contact period of 60 minutes, an adsorbent dosage of 0.1 g, an initial dye concentration of 80 ppm, and a pH of 8.0. Consequently, the produced ZnO NPs show great promise as an efficient adsorbent for removing methylene blue dye, especially when it comes to treating pharmaceutical wastewater.

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ABSTRACT Titanium alloys are utilized in many fields of science, engineering, and technology because of their superior mechanical and tribological properties. The investigation goal is to develop an innovative composite for use in the automobile industry by applying additive processes such as selective laser melting and reinforcing titanium alloy with bio-silica. Bio-Silica (BS) nanoparticles are extracted using agricultural waste of Calotropis gigantea as reinforcement. The Industrial Grade Titanium (IGT) alloy nanocomposites are employed for making alloys with bio-silica nanoparticles reinforcement of 0, 5, 10, and 15%. The IGT/BS nanocomposites mechanical properties, such as microhardness, tensile (ultimate and yield) strength, and compressive strength, were investigated. According to the investigation's outcomes, 15wt.%IGT/BS nanocomposites had better mechanical characteristics. L9 Taguchi's orthogonal array is utilized to illustrate the wear trials. ANOVA is used to optimize outcomes. The ANOVA was utilized to determine the ideal process parameters that would result in the lowest possible wear rate and coefficient of friction (COF). The findings indicated that the applied load of 30 N, sliding velocity of 4 m/s, and sliding distance of 2000 m may achieve the lowest wear. According to an ANOVA, load is the most significant factor (30%) influencing wear.

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ABSTRACT Composite materials, renowned for their superior mechanical properties and lightweight characteristics, are widely used in high-precision industries such as aerospace, automotive, and chemical manufacturing. The production of composite components heavily relies on high-quality molds, where contaminants like mold release agents and resins accumulate over time, compromising the surface quality and durability of both the mold and the composite products. This study investigates laser cleaning as a non-contact, sustainable method to remove these contaminants while preserving material integrity. Surface characteristics were analyzed using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The optimal laser parameters—200 W power, 2500 mm/s scanning speed, 2000 kHz repetition rate, 40 ns pulse duration, and a 0.01 mm scanning interval—effectively removed contaminants and improved surface quality, reducing roughness from 1.840 μm to 0.474 μm. Additionally, mechanical properties were assessed using a micro hardness tester and a multi-function tribometer, showing a 13% increase in surface hardness and an 8% improvement in wear resistance, indicating enhanced surface tribological properties. These findings underscore the potential of laser cleaning to maintain composite mold quality, extend service life, and provide an efficient, environmentally friendly alternative to conventional methods.

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ABSTRACT The growing global energy demand and environmental concerns underscore the importance of optimizing solar water heating systems (SWHS) with an emphasis on material properties to enhance thermal efficiency. Despite technological advancements, challenges in material selection, riser tube design, and operational parameters limit the performance of SWHS. This study focuses on optimizing the thermal efficiency of a solar flat plate collector by integrating material analysis within a combined Computational Fluid Dynamics (CFD) simulation and Response Surface Methodology (RSM) framework. By exploring the effects of riser count, material conductivity, mass flow rate, and inclination angle, the study demonstrates how material properties significantly influence heat transfer. Copper, as the absorber material, exhibited superior thermal performance, with optimized conditions achieving a maximum outlet temperature of 350.61 K. The combined CFD-RSM methodology minimized experimental iterations and provided a deeper understanding of the interplay between material properties and system dynamics. These findings highlight the critical role of material selection in developing cost-effective, high-efficiency solar absorbers. Future research should investigate advanced materials and innovative geometries to enhance the performance and sustainability of SWHS further.

Abstract in English:

ABSTRACT The Design of Experiment (DOE) technique was used to assess the impact of factors such as silica fume, bamboo fibers, and jute fibers on concrete strength. The Box–Behnken design of Response Surface Methodology (RSM) identified the optimal combination of variables and their effects on split tensile and compressive strength at 14 and 28 days. Pareto charts and Analysis of Variance (ANOVA) were used to analyze regression models for these responses. In this study, the jute and bamboo fibers with Silica Fume mixed concrete (each 0.5%) provides the maximum compressive strength of 30.27 MPa and split tensile strength of 3.19 MPa after 28 days of curing. After determining each progression variable’s statistical significance, second-order polynomials were used to create the resulting models. The quality of concrete strength was increased by adding bamboo and jute fibers along with silica fume and further addition of these fibers may reduce the strength of the concrete. The Response Surface and Pareto chart recommended the most significant and influential element for spilt tensile strength is jute and bamboo fibers, and for compressive strength is a jute fiber. Regarding split and compressive strength, the validation test percentage error is less than 3% and 4%, respectively.

Abstract in English:

ABSTRACT Long-neck glass bottles are not returned for reuse by the industry, which has generated a large quantity of waste with environmental impacts for current and future generations. The main raw material employed to synthesize geopolymeric materials is metakaolin, although the relationship between silica and alumina content is not ideal. Often, the silicates in the activating solution complement the required SiO2 content. An eco-efficient option would be to use long-neck bottles as an additional source of silica. This work evaluates plastic viscosity, microstructural, and mechanical characteristics of non-conventional metakaolin geopolymers based on long-neck bottles waste incorporation from the replacement of 0, 10, 20, and 30% of metakaolin with waste from blue, green, and amber long-neck bottles. The best combinations of SiO2/Al2O3, NaOH concentration, and curing temperature were selected to produce geopolymers, which were evaluated through rheology, x-ray diffractometry, and compressive strength. The results indicate a lower flow resistance of geopolymers with residue, in accordance with the increase in the residue content in the system. The occurrence of geopolymerization was observed with and without glass waste, with ambient and thermal curing. The compressive strength, at 90 days of the geopolymers with 10% replacement was higher than the value of the reference sample by 4.1%, 29.1% and 21.0% for the blue, green and amber long neck residues, respectively.

Abstract in English:

ABSTRACT Alloys of the Al-Mg-Sc system are possible options for use in aircraft aiming to reduce structural weight and fuel consumption, due to the demand for advanced metal alloys with better properties, but at a less attractive cost. Considering the potential of these alloys, the present work aimed to evaluate the use of Scalmalloy® in one aircraft component: wings spars, and the values of desired properties for this component were discussed. The mechanical properties of these alloys were consulted in the Aleris datasheet for alloys 5024 and 5028. Consultations were made to the data in the literature, and subsequent comparisons of values of the mechanical properties and Merit Indexes: E1/2/ρ, δy2/3/ρ, E1/2/Cmρ, δy2/3/Cmρ between Scalmalloy® and the traditional alloys, using Cambridge Engineering Selector® 2019 software. It can be seen in the results indicated in Ashby diagrams and tables produced that, for wings spars, the Al-Mg-Sc AA5028-H116, produced by additive manufacturing, has the highest index E1/2/ρ equal to 3.19 and the highest index δy2/3/ρ equal to 25.313. However, the index E1/2/Cmρ is equal to 0.17 and the index δy2/3/Cmρ is equal to 1.35. Therefore, it was found that AA5028-H116 has the potential to replace the traditional alloys, despite its higher price.

Abstract in English:

ABSTRACT Due to the huge demand and scarcity for river sand, there is a desperate need for a Quantitative, Qualitative and Environmentally friendly alternative for river sand. As aggregate is the second largest resource used next to water, the alternative for river sand suggested should be not only of good quality but also should be available in enough quantity to be substituted for river sand. Such alternate choices should not just satisfy the structural requirements but also not affect the environment. In this regard, the environmental valuation of mountains is carried out to assess the benefits and limitations of using M sand as a substitute for river sand. In this study, the chemical properties of M sand samples from various locations are determined along with the lifecycle assessment of M sand. Finally, the Environmental Valuation of mountains is done to determine if the negatives outweigh the benefits. From the results, the various methods to resort to in order to achieve a sustainable level of replacement of M sand with river sand are discussed.

Abstract in English:

ABSTRACT This work examines the impact of altering the water-binder ratios (w/b) and cement/silica fume (SF) replacements on the strength at the compression of High-Performance Concrete (HPC), both before and during prolonged contact with extreme temperature. After preparation and testing, eighteen mixtures were produced. Based on the variation in weight/bulk density, the compressive strength test results at room temperature varied from 58 to 102 MPa. In addition, a novel technique known as “heat endurance” has been implemented to compare HPC responses at high temperatures. The findings demonstrate that pozzolanic interaction with the fillers component of SF improves HPC’s residual compressive strength following exposure to high temperatures. Comparative measurements of retained strength of compression were greatest for blends containing 6%, 12%, and 15% of SF at w/b ratios of 0.30, 0.35, and 0.40. As a consequence, altering the w/b ratio had a substantial impact on the outcomes. Lastly, a variety of measuring methods were offered to assist with the study, such as CT, SEM, and thermogravimetric (TG) analysis to evaluate the microstructure modification, porosity, and mass loss of HPC.

Abstract in English:

ABSTRACT Concrete is the most used construction material, which results in harmful impacts on the environment due to the consumption of natural resources. Hence the need to use alternative materials, e.g., waste from the construction sector and even from other production sectors. This context includes the development of concrete with sustainable functionality, such as pervious concrete with the incorporation of waste foundry sand (WFS), a waste generated by the foundry sector. However, there is a scientific gap focusing on the environmental viability of pervious concretes. In this sense, this study aims to evaluate the toxicity of pevious concretes with WFS, through germination tests with Eruca sativa (arugula) and Triticum aestivum (wheat) seeds. The statistical analysis of the results showed that there was no significant harmful effect from the incorporation of WFS on the germination rate for both seeds used. Regarding root growth, it was observed that WFS II concrete (>% Portland cement) had a lower impact on arugula seeds (more sensitive). Therefore, the pervious concrete with WFS developed was found to be safe in relation to phytotoxicity.

Abstract in English:

ABSTRACT Cyclones are industrial equipment widely used to induce the separation of suspended solid particles based on a driving force related to the terminal velocity in fluid flow. They are applicable to both gaseous and liquid fluids (hydrocyclones), enabling separation between the solid-fluid physical states. The physical principle behind the separation and operation phenomenon is inertia, utilizing centrifugal force to displace air, consequently facilitating the removal of particulate matter present in the stream. One of its main functions is gas cleaning in industrial processes, due to its low acquisition, operation, and maintenance costs, along with the ability to handle streams at high pressures and temperatures. The primary objective of this study is to simulate the flow and disaggregation profiles in a cyclonic separator using computational fluid dynamics (CFD) via finite volumes, where a control volume is subdivided into discrete elements aimed at referencing points within the continuous domain. This approach enables the application of constitutive equations, converting partial differential equations into systems of linear equations. This study applies the method to a Lapple-type cyclone, validating the numerical results obtained with those available in the scientific literature under the same operating conditions. The comparative parameter used to estimate the relative error was the pressure drop. As a secondary objective, the applicability of the cyclone for neutralizing the hazardous chemical agent ammonia was evaluated. This was achieved through its chemical reaction with acetic acid, enabling a realistic hypothetical leakage study to investigate the possibility of formulating emergency plans. In the event of an industrial accident involving ammonia dispersion, this system could be activated. For this purpose, a multiphase plug flow reactor (PFR) was designed, estimating the conversion, reaction time, and dynamic concentration profiles for the synthesis of ammonium acetate, a chemical agent with lower toxicity compared to ammonia.

Abstract in English:

ABSTRACT In order to investigate the effect of periodic solar radiation on oil vapor diffusion and small breathing losses in dome roof tanks, a theoretical model of unsteady heat and mass transfer in dome tanks is established based on the ASHRAE clear-sky model and oil evaporation theory. The heat flux UDF is self-programmed, and CFD software is used to simulate the heat and mass transfer process in the gas space of the dome tank. Dynamic mesh technology is used to realize the overpressure relief of the breathing valve and calculate the small breathing losses. The results show that the gas space temperature decreases from top to bottom; it has a concave and convex distribution near the tank wall. The average temperature decreases with increasing liquid level. The vapor concentration in the gas space increases from top to bottom, and there is a clear concentration layer near the liquid level. The average vapor concentration increases with the liquid level. Gas space pressure increases gradually from top to bottom. The number of breathing valve exhausts decreases with the increase in liquid level. The small breathing losses increase with the liquid level and the seasonal warming, and the loss rate increases with the seasonal warming.

Abstract in English:

ABSTRACT The morphology of LPSO phase, mechanical properties and fracture behavior of Mg-8Gd-5Y-2.5Zn-0.6Zr (wt%) alloy were systematically studied. The microstructure of as-cast and homogenized alloys is mainly composed of α-Mg matrix and Mg12(Gd,Y)Zn eutectic phase (LPSO phase). The as-cast alloy contains a large number of fine block 18R LPSO phases, which can be transformed into lamellar, rod-like and large block 14H LPSO phases after homogenization at 520°C for different time. Homogenization treatment can significantly improve the mechanical properties of Mg-8Gd-5Y-2.5Zn-0.6Zr alloy, especially the plasticity. The fine block and lamellar LPSO phases are prone to stress concentration, causing transgranular cleavage fracture, thereby damaging the mechanical properties of the alloy. The rod-like LPSO phase is easy to form pinning effect in the matrix, which can effectively improve the mechanical properties of the alloy and cause transgranular and dimple fracture, so that the alloy obtains the best ultimate tensile strength, yield strength and elongation, which are 252MPa, 214MPa and 17.2%, respectively.

Abstract in Portuguese:

RESUMO O processo de corrosão nos metais compromete a estrutura e o funcionamento de diversos materiais utilizados no cotidiano. Revestimentos e modificações superficiais que retardem a evolução do processo corrosivo são os métodos de proteção mais utilizados. Os revestimentos termodifundidos de carboneto de vanádio foram desenvolvidos para melhorar o desempenho e a vida útil de ferramentas de aço para conformação plástica de metais. Neste trabalho avaliou-se a resistência à corrosão de revestimentos de carboneto de vanádio termodifundidos e aplicados por laser cladding sobre o aço ferramenta AISI D2. Os revestimentos foram caracterizados quimicamente por difração de Raios X. Para avaliar a resistência à corrosão utilizou-se técnicas eletroquímicas, como a espectroscopia de impedância eletroquímica (EIS) e, a análise da microestrutura foi realizada por microscopia eletrônica de varredura com sonda. Os resultados dos ensaios eletroquímicos mostraram que a camada de carboneto de vanádio pelo processo de laser cladding do aço AISI D2 apresentou resultado significativo à resistência à corrosão. No processamento via laser, a fusão, convecção e solidificação do pó de carboneto de vanádio (VC) e da superfície do substrato fazem com que o cromo presente no substrato seja distribuído uniformemente não só na camada de carboneto de vanádio por laser cladding (VCLC) como na região logo abaixo, na zona térmica afetada (ZTA) pelo aquecimento. A resistência a corrosão foi observada nas análises feitas por microscopia eletrônica de varredura quanto à homogeneidade da camada. As análises por dispersão de raios X (EDS) e por difração de raios X (DRX) apresentaram teores do elemento ferro em níveis reduzidos, adequados para a boa resistência à corrosão.

Abstract in English:

ABSTRACT The corrosion process in metals compromises the structure and operation of various materials used in daily life. Surface coatings and modifications that delay the evolution of the corrosive process are the most commonly used protection methods. Vanadium Carbide Thermo-diffusion Coatings (VCTD) have been developed to improve the performance and life of steel forming tools. In this work, we evaluated the corrosion resistance of vanadium carbide coatings produced by thermodiffusion and by laser cladding on tool steel AISI D2. The coatings were characterized by electrochemical techniques to evaluate the corrosion resistance, scanning electron microscopy with probe, for analysis of the microstructure and chemical composition followed by X-ray diffraction. The results of the electrochemical tests showed that the layer of vanadium carbide by the laser cladding process of AISI D2 steel presented better resistance to corrosion. In laser processing, the VC powder and substrate surface rapid melting and metallic elements diffusion causes the chromium present in the substrate to be uniformly distributed not only in the layer of layer but also in the region just below, in the affected thermal zone (ZTA) by heating. The high corrosion resistance was consistent with the analysis made by scanning electron microscopy on the homogeneity of the layer. X-ray energy dispersion and X-ray diffraction presented iron element contents at reduced levels, suitable for high corrosion resistance.

Abstract in English:

ABSTRACT This study presents a novel approach for synthesizing a highly efficient oxygen reduction reaction (ORR) catalyst derived from natural wool fibers through a one-step pyrolysis process. The resulting FeCo-carbon fiber composite exhibits a unique hierarchical structure with a BET surface area of 786 m2/g and a micropore volume of 0.31 cm3/g. X-ray photoelectron spectroscopy reveals significant nitrogen doping (6.4 at%) and the presence of catalytically active Fe and Co species. In alkaline medium, the catalyst demonstrates exceptional ORR performance with an onset potential of 0.98 V and a half-wave potential of 0.85 V vs. RHE. The material achieves a limiting current density of 5.8 mA/cm2 and an electron transfer number of 3.92, indicating a predominant four-electron pathway. Notably, the catalyst retains 92% of its initial current density after 20 hours of continuous operation and exhibits superior methanol tolerance. In acidic medium, the catalyst maintains promising activity with an onset potential of 0.83 V and a half-wave potential of 0.72 V vs. RHE. The synergistic effects of FeCo alloy nanoparticles, nitrogen-doped carbon, and a partially graphitized structure contribute to the material’s outstanding catalytic properties. This work not only introduces a sustainable and cost-effective approach to ORR catalyst synthesis but also highlights the potential of animal-derived biomass in developing high-performance electrocatalysts for energy conversion applications.

Abstract in English:

ABSTRACT This work models numerically the concrete mechanical behaviour using a two-dimensional model at mesoscopic level and using the concept of Representative Volume Element (RVE). Concrete is considered as three phases material: mortar/aggregate interface, mortar matrix and aggregate zones, where each constituent is modelled properly. The aggregates are considered to behave elastically, while the Mohr-Coulomb criterion defines the mechanical behaviour in the mortar matrix. Different strategies are used to model the fracture process at the interface transition zone: i) defining rectangular finite elements along interfaces where a fracture/contact model is incorporated; ii) adopting triangular finite elements where the Mohr-Coulomb model is used with lower strength characteristics compared to the mortar matrix. In the numerical examples, we study which of these two strategies is more efficient for modelling the transition zone. Besides, in the RVEs we consider different shapes for the aggregates, which are randomly arranged, with different volume fractions. The results evidence the potentialities of the proposed modelling, but they also show the high sensibility of parameters related to fracture and contact models what can restrict their use for interface zone modelling.

Abstract in English:

ABSTRACT Electric Discharge Machining (EDM) is one of the most effective unconventional material removal techniques that mill electrically conductive objects, despite their hardness using electrical discharge. This elite method provides excellent accuracy and surface finish within short duration. The presented research envisages to study the effect of process variables of EDM namely Pulsating Current (I), Pulse-on-time (Ton) and Pulse-off time (Toff) on machining performance measures namely Tool Wear Rate (TWR), Surface Roughness (SR) and Material Removal Rate (MRR). The best possible condition for specimen selection is presented by a new technique known as Multi Attribute Recursive Optimization (MARO). The optimal experimental conditions were found with Ton 100 s, Toff 49.82 s, and I 4.99 A, with ideal responses of SR 0.057 µm, MRR 0.036 g/min, and TWR 3.301 g/min. For the best run identification, the METHod for Enrichment Evaluation, Preference Ranking Organization METHod (PROME-THEE) was used while Historical Data Design (HDD) was used to validate the result obtained. The integration of PROMETHEE and HDD known as MARO is identified to appreciate degree of the methods analyzed. The close convergence of PROMETHEE and HDD at 97% guarantees the accuracy of the proposed MARO technique.

Abstract in English:

ABSTRACT This study focuses on optimizing and predicting the drilling performance of Fiber Metal Laminates (FMLs) reinforced with BaSO4 nanoparticles, achieved by adjusting parameters like spindle speed, feed rate, and tool diameter. Key responses—thrust force, torque, delamination, and surface roughness—were evaluated to enhance machinability. Using Central Composite Design, optimal parameters were identified: a spindle speed of 3000 rpm, feed rate of 10 mm/min, and tool diameter of 6 mm. Under these conditions, thrust force decreased by 51.92%, surface roughness improved to Ra = 2.3 µm, and delamination reduced by 21%. A two-layer feed-forward neural network in MATLAB 2023a accurately predicted outcomes with a Mean Square Error (MSE) of 1.4025e-05, demonstrating high correlation with experimental data. The inclusion of BaSO4 nanoparticles significantly improved the FMLs’ mechanical and thermal properties, enhancing machinability. This integrated approach of experimental optimization and predictive modeling provides a strong framework for precision machining of hybrid composites. The findings are especially promising for aerospace and automotive industries, where defect-free, high-quality FML machining is essential, positioning this method as a key advancement in nanoparticle-reinforced composite drilling.

Abstract in English:

ABSTRACT Air pollution is a critical environmental problem driven by urbanization and industrialization. Time-series forecasting using previous methods is difficult because models must account for seasonal changes, day-to-day changes, and emergencies that can rapidly affect air quality. Therefore, existing approaches struggle to predict these fluctuations. This research addresses this issue by proposing a material-focused method of air quality prediction using machine learning techniques. The proposed model incorporates feature selection using MS-ANFIS-FS and classification using Unet-RNN (Unet Optimized Recurrent Neural Network). The model focuses on analyzing pollutant interactions with material surfaces, improving prediction accuracy by considering the role of materials in pollutant dispersion and absorption. The Successive Feature Defect Scaling Rate (SFDSR) and Auto-Regressive Integrated Moving Average (ARIMA) methods detect variance dependencies in air quality data. These methods enable the model to identify material traits influencing pollution levels, yielding more accurate results for pollutants like PM2.5 and NO2. The findings demonstrate the critical importance of material properties in environmental management and show how material-based interventions can effectively reduce air pollution. This model has the potential to facilitate real-time pollution monitoring and support the development of sustainable air quality management strategies.

Abstract in English:

ABSTRACT This study examined the behavior of two-span continuous beams reinforced with Engineered Cementitious Composite (ECC) under static loads, showcasing ECC’s significant ability to enhance the flexural strength, durability, and overall resilience of conventional concrete structures. The research focused on assessing how ECC layers contribute to the structural integrity, load-bearing capacity, and crack development of the beams, utilizing a mix of materials including Ordinary portland cement (OPC) 43 Grade, fly ash, manufactured sand, polypropylene fibers, silica fume, superplasticizer, water, and coarse aggregates. The flexural tests indicated that replacing traditional concrete with ECC led to substantial improvements in load-carrying capacity and ductility, with ECC’s unique properties resulting in reduced crack widths and spacing in tension zones. Additionally, the study highlighted ECC’s advantages in terms of energy absorption and post-cracking behavior, suggesting that beams with ECC could exhibit longer service life and lower maintenance requirements. The integration of ECC also enhanced protection for the longitudinal reinforcement, indicating its potential for use in seismic-resistant designs and other high-performance applications. Overall, the findings underscore ECC’s transformative role in improving the performance and sustainability of concrete structures in modern engineering.

Abstract in English:

ABSTRACT This study recommended a micro-surfacing cold-mix binder with good water stability, high- and low-temperature property and fast curing rate. Additionally, a dynamic water disturbance experiment method to evaluate the adhesion of composite modified emulsified asphalt was developed. Initially, the optimal SBR content is determined through performance tests, followed by selected a suitable WER system via film-forming experiments. Various WER-SBR composite-modified emulsified asphalt formulations are prepared by adjusting WER concentrations. The properties of WER-SBR modified emulsified asphalt were comprehensively evaluated using methods including penetration, softening point, ductility, Brookfield viscosity, storage stability, dynamic water disturbance experiment, dynamic shear rheometer, scanning electron microscopy, and fluorescence microscopy, and the appropriate range of WER content was discussed. The results of the study showed that when the SBR content was 3%, the comprehensive performance of the modified emulsified asphalt was optimal. The addition of WER could improved the high-temperature performance and adhesion of SBR modified emulsified asphalt, but it gradually weakened the low-temperature performance and storage stability. Based on the comprehensive evaluation of the experiments, if the modified emulsified asphalt is for immediate use, the recommended WER content is 6%–9%. If the modified emulsified asphalt needs to be stored for one day, the recommended WER content is below 4%.

Abstract in English:

ABSTRACT Handheld electronic devices are vulnerable to drop impacts, leading to mechanical damage and electrical failures such as PCB cracking, trace damage, solder joint fractures, and component breakage. This study investigates the reliability of solder joints in Ball Grid Array (BGA) packages by examining their dynamic response under board-level drop impacts using Finite Element methods. Explicit dynamic analysis employing the Input-G method, in accordance with JEDEC guidelines, was used to simulate the printed circuit board assembly (PCBA) model. Results reveal that solder balls on the board side are more critical than those on the package side, with corner-most solder balls near the board edges identified as the most vulnerable, experiencing maximum peel stress of 162.12 MPa and strain of 0.001048. Analysis of radial displacement and drop orientation showed that BGA packages positioned closer to PCB edges exhibit greater reliability than those at the centre. The face-down drop orientation was identified as the most vulnerable configuration. Structural optimization of the PCBA, incorporating factors such as solder ball pitch, PCB thickness, and solder ball diameter, significantly improves reliability, underscoring the importance of these parameters in ensuring the long-term durability of the assembly.

Abstract in Portuguese:

RESUMO O objetivo da pesquisa foi avaliar as propriedades físicas e mecânicas de blocos intertravados para pavimentos com a incorporação de casca de arroz in natura em sua composição. Foram adotadas as proporções de 0%, 5%, 10%, 15% e 20% de casca de arroz em relação à massa seca do cimento. Após a cura os blocos foram realizados: inspeção visual, avaliação dimensional, absorção de água, resistência à compressão e densidade. Os blocos produzidos com 20% apresentaram elevada fragilidade. Para os demais blocos com casca de arroz observou-se alterações das peças através do surgimento de espaços vazios e falhas nas arestas dos blocos. A incorporação da casca de arroz não modificou a resposta dimensional dos blocos, com valores de Índice de Forma compatíveis com os vigentes na norma. Considerando os tratamentos com adição da casca de arroz, o melhor desempenho para os parâmetros de absorção de água, resistência à compressão e densidade foi verificado com a incorporação de 5% de casca de arroz nas peças. Sugere-se expandir estudos para aprimorar tratamentos físicos e químicos na casca de arroz in natura, a fim de compreender melhor suas propriedades e utilização como reforço em compostos cimentícios.

Abstract in English:

ABSTRACT The research objective was to evaluate the physical and mechanical properties of paving blocks after incorporating raw rice husks into their composition. The proportions of 0%, 5%, 10%, 15% and 20% rice husk in relation to the dry mass of the cement were adopted. After curing, the pavers were subjected to visual inspection, dimensional evaluation, water absorption, compressive strength and density. The blocks produced with 20% showed high fragility. For the other pavers with rice husk, changes in the pieces were observed through the appearance of empty spaces and flaws on the edges of the blocks. Incorporating the rice husk did not modify the dimensional response of the blocks, with Shape Index values compatible with those in force in the standard. Considering the treatments with adding rice husk, the best performance for water absorption, compressive strength, and density was verified by incorporating 5% rice husk in the pieces. It is suggested to expand studies to improve physical and chemical treatments of rice husk in nature to better understand its properties and use as reinforcement in cementitious compounds.

Abstract in English:

ABSTRACT Lead is a hazardous heavy metal known for its severe health impacts, including its association with cancer. In this study, copper-doped activated carbon was synthesized using copper acetate and bean husk, activated chemically through potassium hydroxide (KOH). The data was fitted by the Langmuir isotherm model more accurately than by any other isotherm, and the adsorption capacity of Cu-AC nanoparticles was found to be 94.339 mg/g. For the removal of lead ions over Cu-AC nano-adsorbent, when comparing the values of qe calculated and qe experimental. Activated copper doped carbon has the capacity to operate as an adsorbent in the treatment of lead metal ion pollution and other associated heavy metal ion pollutants. Surface chemistry analysis identified hydroxyl, amino, aromatic, and carbonyl functional groups. Field emission scanning electron microscopy revealed interconnected mesoporous structures with numerous open pores. Adsorption experiments demonstrated that the sorption process aligned. The maximum adsorption capacity was recorded at 94.339 mg/g, with a significant desorption efficiency using HCl as the desorbing agent. Thermodynamic analysis confirmed that the lead ion removal occurred primarily through a physisorption mechanism.

Abstract in English:

ABSTRACT In this paper, the bonding properties between rebar and polyurethane concrete (PC) through pull-out tests of PC and rebar is investigated. The effect parameters such as the protective layer thickness of the specimen, the anchorage length of the rebar, the diameter and shape of the rebar on the bonding performance were considered separately. It was shown that the thickness of the protective layer significantly affects the bond strength between the rebar and the PC, and the bond strength increases with the increase of the thickness of the protective layer. The average bond stress is 12.36 MPa for a protective layer thickness of 45 mm, which is an increase of 17.55% compared to 35 mm. The average bond stress is 16.45 MPa at a protective layer thickness of 65, which is a 54.03% increase in stress from 35 mm. The bond strength of rebar to PC decreases with increasing diameter for the same anchorage conditions. The bond stress between the same diameter bars and PC for different anchorage lengths decreases with increasing anchorage length. When the diameter of the rebar is 22 mm, the bond stress between the rebar and the PC is 13.7 MPa, which is a 24.10% reduction in stress compared to 14 mm. The bond strength of rebar to PC decreases with increasing diameter for the same anchorage conditions. And the bond strength of ribbed bars is significantly higher than that of bare round bars. The research results can lay a foundation for the engineering application of polyurethane reinforced concrete.

Abstract in English:

ABSTRACT A copper – graphene base composite is developed with different hard particle reinforcements through the powder metallurgy process. The different reinforcement particles are silicon carbide (SiC), titanium carbide (TiC), zirconium oxide (ZrO2) and aluminum – magnesium (AlMg) at equal weight percentages. The spherical copper powder with irregular reinforcement particles got pressed during the powder compaction and deformed to form a strong structure. During sintering the powder compaction has undergone metallurgical diffusion and the bonding between the reinforcement and matrix material. The microstructure of the pure copper and the copper – graphene with different reinforcement is compared for discussion. The hardness of copper and copper – graphene – titanium carbide composite is maximum and similar in results. The density of copper – graphene – titanium carbide composite is two-fold harder than the copper – graphene – aluminum magnesium composite material. Subsequently the porosity of the AlMg reinforcement is less as the diffusivity is higher than the other reinforcements.

Abstract in English:

ABSTRACT This study develops an IoT-based real-time framework for monitoring concrete strength in structural frameworks, utilizing electrochemical and fiber optic sensors to enhance construction quality control and structural health monitoring. Accurate assessment of concrete strength is vital for ensuring the safety and longevity of infrastructure. Traditional testing methods, which are periodic and invasive, often fail to provide timely data on strength progression. This framework overcomes these limitations by enabling continuous, in-situ monitoring. Electrochemical sensors measure variations in the chemical environment of concrete, which correlate with strength development. Simultaneously, fiber optic sensors monitor strain and temperature changes, providing real-time insights into structural responses under load. The data collected by these sensors are analysed using the Plowman method and regression curve analysis, offering high precision in detecting early-stage strength development and modelling its progression over time. The system incorporates wireless data transmission to a central cloud-based server for storage, processing, and visualization. This approach ensures enhanced lifecycle management and resilience of infrastructures. By demonstrating the efficacy of this IoT-based monitoring system, the study underscores its potential to revolutionize construction practices. It provides a robust solution for real-time quality assurance, structural health monitoring, sustainable lifecycle management, and resilient infrastructures.

Abstract in English:

Abstract The study aims the performance of presoaked light expanded clay aggregate (LECA) and fly ash aggregate (FAA) as partial replacement of river sand in self compacting concrete (SCC). On a volume basis, presoaked LECA and FAA partially replace river sand. LECA and FAA are presoaked for 24 hours before casting of SCC. The water retained in the lightweight aggregates (LWAs) pores acts as an internal curing reservoir. SCC workability characteristics, including as flowability, filling and passing capabilities, resistance to segregation, and concrete bleeding, were evaluated using slump cones, U-boxes, L-boxes, V-Funnels, and J-ring tests. Addition of LECA and FAA reduces the water for curing and also attain good workability and strength of SCC. The durability characteristics such as sulphate attack, acid attack are conducted in various durations like 7, 28, 56, 90, 180 days. Further, bond strength and accelerated corrosion tests also conducted. From all the mechanical and durability tests on SCC with LECA and FAA by 15% replacement for fine aggregate shows more beneficial effect in strength, microstructural and durability properties than those demonstrated by control mix concrete.

Abstract in English:

ABSTRACT A heat pipe with low thermal resistance and high thermal conductance is one of the most effective heat transfer devices. It can move large amounts of heat over a small cross-sectional area with extremely little temperature variations between the two temperature limits. This study uses Design of Expert software to evaluate the performance of various nanofluids as the working fluid for the heat pipe, including copper oxide, graphene oxide, iron oxide, and titanium oxide. The base fluid used in this analysis is an aqueous solution of n-Octanol. The parameters considered in this analysis are the condenser flow rate, filling ratio, angle of inclination, and heat input. In order to assess the thermal efficiency of the heat pipe's working fluids, all operational factors are assessed using the Central Composite Design (CCD) matrix and Response Surface Methodology during experiment design. The experimental findings demonstrate that the suggested model can predict the heat pipe's thermal efficiency to within 1% of the variation. As a result, the suggested model can be used to forecast the heat pipe's thermal efficiency.

Abstract in English:

ABSTRACT This study presents an investigation into the challenge of alleviating heavy metal pollution while using red mud (RM) as an industrial byproduct, focusing on its application in the preparation of geopolymers. Synthesis RM-ground granulated blast furnace slag (GGBS)-based geopolymer (RMG) and studied with particular attention to optimizing compressive strength through modifying key parameters: RM content, Na2SiO3 modulus, and water-to-binder ratio. The immobilization of heavy metals, particularly lead (Pb) and copper (Cu), within geopolymer was thoroughly examined. Results indicate that optimal compressive strength was achieved at a 40 wt.% RM content, a Na2SiO3 modulus of 1.8, and a water-to-binder ratio of 0.65, with 28-day compressive strengths reaching 36.9 MPa. A 1% mass of heavy metals was observed to improve the mechanical characteristics of the geopolymer; however, beyond this threshold resulted in detrimental effects. The immobilization capabilities of RMG under various environmental conditions were robust, with immobilization efficiencies exceeding 97% for Pb and 94% for Cu. The immobilization mechanism was found to involve physical encapsulation, with Cu uniquely forming covalent bonds with non-bridging oxygens within the polymeric structure, creating stable Si-O-Cu bonds. This study highlights the potential of geopolymer as a viable technology for mitigating environmental impacts associated with RM disposal by effectively immobilizing heavy metals, thus facilitating safe and sustainable resource utilization. This work contributes to the field by demonstrating a novel approach to the valorization of industrial waste, offering a promising solution for the management of RM while addressing the critical issue of heavy metal pollution.

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ABSTRACT This study investigates how the workability and mechanical qualities of concrete are affected by adding different amounts of Ordinary Portland Cement (OPC), Ground Granulated Blast Furnace Slag (GGBS), Fine Aggregate (FA), Coarse Aggregate (CA), and Lightweight Expanded Clay Aggregate (LECA). Traditional coarse aggregates were replaced with GGBS ranging from 5% to 20% and LECA included at varying degrees in a range of concrete mixtures. Slump, L-box, V-funnel, J-ring, and U-box tests were used to evaluate workability, while tests for compressive strength, split tensile strength, and flexural strength were used to evaluate mechanical characteristics at 7, 14, and 28 days. The results showed that workability and compressive strength increased with increasing GGBS concentration, with 15% GGBS achieving a maximum of 68.34 MPa. However, higher proportions of LECA negatively impacted mechanical strength. The optimal mix comprised 85% OPC, 15% GGBS, and a balanced LECA content, achieving enhanced workability without compromising strength. This research highlights the potential for sustainable concrete production by utilizing waste materials while ensuring structural integrity.

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ABSTRACT Micro/meso fabrication techniques have gained significant recognition globally for their advanced manufacturing capabilities. Among these, microforming stands out as a leading process in micromanufacturing. Despite growing interest in microextrusion for industrial applications, the technology remains underdeveloped compared to conventional forming methods, with limited expertise available. To address this gap, it is essential to develop a comprehensive understanding of the microextrusion process, which can guide the production of metallic microcomponents. This research focuses on the numerical simulation of microextrusion to study the influence of die entry angles on the deformation behavior of AA6063 aluminum alloy. Simulations were conducted using die angles of 15°, 30°, 45°, and 60° under varying frictional conditions. Results show a direct relationship between die angle and forming load, while punch displacement decreases as the die angle increases. The role of friction was also found to be crucial in the extrusion process. Numerical results for the 30° die angle were compared with experimental data, highlighting the effectiveness of finite element analysis in predicting microforming outcomes. This study demonstrates the potential of numerical simulation as a powerful tool for optimizing microforming processes in industrial applications.

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ABSTRACT This research paper aims to develop hybrid fibre-reinforced Engineered Cementitious Composites (ECC) deploying different modulus of fibre and to explore the mechanical and flexural response of newly refined Hybrid ECC in the 30 mm thick bottom layer of reinforced concrete (RC) beams. This investigation uses five combinations in the RC beam. The focus of hybridization is to increase the flexural response and structural functioning of RC beams. ECC mixes were attempted with the deployment of Polyvinyl Alcohol (PVA) Fibre and Polypropylene (PP) fibre with 2% as a mono fibremix. Hybridization is made with 0.65% of PVA and 1.35% of PP, 1% of PVA and 1% of PP, 1.35% of PVA, and 0.65% of PP. In this research investigation, mono fibre ECC with 2.0 % PVA fibre mix was taken as a base mix for comparison. From the behavior of the beam, it was found that the mix with PVA fibre of 1.35% hybrid with PP fibre of 0.65% exhibited better performance in flexural when compared with conventional concrete. However, PP fibre of 2% volume fraction has high energy absorption capacity, and PVA fibre of 2% volume fraction has high ductile displacement compared to conventional concrete.

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ABSTRACT The consequences of partially substituting electronic trash (e-waste) for traditional aggregates in concrete compositions are examined in this study. When compared to conventional mixes, the testing findings show that adding e-waste improves the mechanical qualities and durability of concrete. Specifically, compressive strength peaked at 30.19 MPa for the mix containing 12% e-waste, significantly surpassing the conventional concrete's strength of 25.21 MPa. Improvements were also observed in split tensile and flexural strengths, with maximum values of 2.00 MPa and 2.64 MPa, respectively. The modified concrete showed reduced water absorption and porosity, indicating enhanced durability. Notably, the resistance to sulfuric acid attack improved, with the lowest weight loss (5.52%) and strength loss (6.39%) recorded in the e-waste mix. These findings affirm that utilizing e-waste in concrete not only contributes to superior mechanical performance but also enhances resistance to environmental challenges. This research promotes the sustainable use of e-waste in construction, supporting eco-friendly practices and effective waste management strategies.

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ABSTRACT Natural sand is a crucial ingredient that is used in cement planning and is also crucial to mix design. This paper examines the fundamental characteristics of concrete that contains both full and partial replacements of natural sand with manufactured sand (M-Sand). In this study, an attempt is made to preserve natural resources like natural sand by partially substituting M-Sand for natural sand. In order to examine the intrinsic characteristics of strength and durability in concrete, samples designated as M1CC, M2CM, M3CSMS, M4CSRS, M5SSRS, and M6SSMS were selected for analysis. A series of experimental assessments were performed to evaluate the compressive strength, split tensile strength, and flexural strength of both conventional concrete and M-Sand concrete within the context of the strength characteristic evaluation. The durability analysis of both conventional and M-Sand concrete was conducted utilizing the sulphate attack test, Acid Attack Test, and the Rapid Chloride Permeability Test (RCPT). Experimental results revealed that concrete with 60% replacement of natural sand by M-Sand exhibited a 20% increase in compressive strength compared to conventional concrete. Durability tests showed a reduction in chloride ion penetration by 25%, and better resistance to acid and sulfate attacks in M-Sand concrete. Morphological analysis indicated that M1CC had higher initial and secondary absorption compared to other specimens, while Scanning Electron Microscopy (SEM) analysis confirmed enhanced microstructural integrity in specimens with optimal M-Sand replacement. These findings demonstrate that partial substitution of natural sand with M-Sand can effectively improve both the strength and durability of concrete.

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ABSTRACT The proposed work presents an approach using different computational intelligence techniques combined with an evolutionary algorithm to predict the mechanical properties of lightweight aggregate concrete. Four regression techniques were used to make it possible to predict properties: multiple-layer artificial neural networks (ANN), support vector machines (SVM), extreme learning machines (ELM), and decision trees (DT), combined with an evolutionary optimisation algorithm, the particle swarm optimisation (PSO) algorithm. For the entire search process, the decision tree had the lowest average execution time, followed by ELM, which also had a low execution time. ANN and SVM obtained a very high average time and standard deviation compared to the other two methods tested. This is due to the different settings used in the search process, such as the number of layers for the ANN and the precision parameter ε of the SVM, which can lead to a drastic change in the learning time of these methods. In contrast, ELM and DT have more stable behaviour in relation to execution time, regardless of the values of the tested parameters. This shows that SVM and ANN are very sensitive to the values used in their parameters in relation to execution time.

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ABSTRACT The present study monitored the rutting behavior of SBS-modified binders from three different crude oil sources, as well as their corresponding mixtures. Three formulations from Brazil and Russia were considered, one of which is a Brazilian highly-modified binder (SMB HiMA) and the other two are conventional SBS-modified materials (Brazilian SMB 60/85 and Russian SMB 65/90). The unmodified materials are from Brazil (AC 50–70) and Colombia (AC 60–70). Binder tests included oscillatory shear and MSCR – especially at the temperature of 64°C – and mixture tests included Flow Number (FN) at 60°C and Hamburg Wheel Tracking Test (HWTT) at 50°C. Out of the binder parameters evaluated here, the nonrecoverable creep compliance at 3.2 kPa (Jnr3.2) and the combined elastic plastic parameter at 3.2 kPa (CEP3.2) showed more similarities with the rankings of mixtures and the highest correlations with FN and HWTT data. Conversely, the percent difference in nonrecoverable compliances (Jnr,diff) poorly matched the mixture rankings, and it also depicted a diametrically opposite pattern of response in the regression trendlines. The findings of the percent slope between the nonrecoverable compliances (Jnr,slope) are more promising than the ones of Jnr,diff, which is in agreement with the literature.

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ABSTRACT Self-Compacting Concrete (SCC) is a very flexible concrete that flows through intricate, heavily reinforced structural components and compacts under its own weight. Natural sand is in extremely high demand in developing countries because of the rapid expansion of the infrastructure. Many researchers are substituting some of the fine aggregate with materials based on slag. Environmental contamination is increased by the production of casting slag, a by-product of the casting industries that can be used to make concrete. Casting slag is a coagulation process result that is a solid in the iron industry. After being identified as garbage, it is usually disposed of in the utility disposal site. As a result, an effort has been undertaken to assess how casting slag affects the amount of Fine Aggregate (FA) replacement in the percentage of be 0%, 10%, 20%, and 30% and abovementioned tests were conducted. The results of the tests demonstrated that casting slag may be utilized efficiently as a substitute in part for fine aggregate in self-compacting concrete, resulting in sustainable construction.

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ABSTRACT Utilization of Nano-structure pyrolytic carbon (NSPC) particles holds significant potential in developing nanocomposites. Consequently, compressive strength is a crucial characteristic which stipulates the efficiency of NSPC particles in cementitious composites. Nevertheless, predicting the compressive strength of this nanocomposite is a significant challenge due to distorted responses and complex structures. The main novelty of this research is to predict the compressive strength of the developed NSPC nanocomposite. Therefore, the machine learning (ML) model is the first-time proposed for predicting the compressive strength of nanocomposite mortar incorporated with various dosages of NSPC particles. In addition, the bound water of the nanocomposite mortar is determined to understand the efficiency of NSPC particles in the hydration process. This work highlights a comprehensive comparison of six ML algorithms, such as linear regression, random forest regression, extra trees, gradient boost regressor, extreme gradient boost, and LightGBM, for prediction accuracy of compressive strength of NSPC nanocomposites. Furthermore, it is evaluated through multiple statistical error analysis. Seventeen parameters were considered input variables to predict the compressive strength of nanocomposite mortar. According to the coefficient of determination analysis, the gradient boost regressor model attained the highest R2 value of 0.87, while the extreme gradient boost and extra trees achieved R2 values of 0.86 and 0.85, respectively. In addition, a low mean absolute error of 3.229 was earned for the extreme gradient boost. Overall, the gradient boost regressor was reliable and performed better in predicting the compressive strength and mapping the interplay between input variables and compressive strength.

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ABSTRACT This study examines how adding fly ash and silica fume to concrete affects its durability and mechanical qualities. Ten concrete mixtures in all, including a traditional concrete mix and several fly ash and silica fume combinations, were assessed. Compressive strength, split tensile strength, permeability, sorptivity, RCPT, and ultrasonic pulse ve-locity (UPV) at various curing ages (7, 14, and 28 days) were among the performance parameters examined. According to the results, at 28 days, ordinary concrete had the maximum compressive strength, measuring 29.66 MPa. The 10% fly ash and 10% silica fume (S6) combination produced the best results among the adjusted mixes, with a com-pressive strength of 32.55 MPa and a split tensile strength of 2.33 MPa. Additionally, the investigation showed that all of the blends had minimal permeability, which suggests strong durability properties. All things considered, adding more cementitious ingredients can improve the qualities of concrete, but the ratios employed are crucial for maximizing results. The results highlight how fly ash and silica fume may be added to concrete com-positions to increase sustainability without compromising structural integrity.

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ABSTRACT A double-fed induction generator (DFIG) based wind energy conversion system (WECS) has been proven to be an efficient solution for electrical energy generation from wind. In this paper, the design process of cascade control loops for the implementation of a maximum power point tracking (MPPT) control algorithm on a DFIG-based WECS is presented. A tip speed ratio algorithm (TSR) was chosen in this work to generate reference turbine speed signals for harvesting maximum energy from all wind profiles. The design methodology of cascade controllers for the power electronics converter is explained in detail in this work and the performance of the system in extracting maximum power from wind is evaluated using Matlab/Simulink simulation tool. The simulation results are proved that the tuned controllers are able to operate the wind energy conversion system at maximum power point in extracting maximum energy from all types of wind profiles.

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ABSTRACT Abrasive water jet machining produces large quantities of spent abrasive particles, typically discarded due to their heterogeneous composition, comprising both metallic and non-metallic components that vary with the processed material. However, these particles can be repurposed for engineering applications. This study utilized spent abrasive particles as filler materials at 2.5%, 5%, and 7.5% by weight in an epoxy resin matrix to fabricate kenaf fiber-reinforced hybrid polymer composites. The tribological properties of the composites were systematically analyzed to identify optimal conditions for minimizing wear rate and friction. Pin-on-disc wear tests were performed using a standard tribometer at sliding velocities of 1 m/s, 2 m/s, and 3 m/s, under loads of 5 N, 10 N, and 15 N, over a constant sliding distance of 800 m. Results showed a minimum wear rate of 0.0108 mm3/m and a minimum coefficient of friction of 0.0581 for composites with 7.5 wt.% filler at a 5 N load and 1 m/s sliding velocity. Worn samples were examined using scanning electron microscopy to explore the dominant wear mechanism. The inclusion of spent abrasive particles significantly improved tribological performance by enhancing wear resistance and modifying frictional behavior through improved interfacial bonding in the polymer matrix.

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ABSTRACT Ti15Mo alloys have recently been attracted in biomaterials due to its favourable mechanical and biocompatibility properties. However, the wear resistance of this alloys should be improved for dental applications. The objective of this in vitro study was to investigate the effects of a TiN film on two-body wear properties of the Ti15Mo alloy. The microstructure properties of uncoated and TiN film-coated alloys were comparatively investigated via X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray spectroscopy (EDS), and microhardness measurement systems. The wear performance of uncoated and coated samples has also been evaluated using a dual-axis computer-controlled wear simulator device in distilled water. Following the completion of the two-body wear test procedures, the mean wear volume loss of all test samples was determined utilising a non-contact 2D and 3D profilometer. The two-body wear resistance of TiN film-coated alloys was superior to that of the uncoated alloys. The coated samples exhibited enhanced wear resistance, which was accompanied by an increase in hardness and a reduction in surface roughness. The mean wear volume loss of coated samples was lower than the other group samples irrespective of test conditions.

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ABSTRACT This study evaluates the performance of an enhanced indirect solar dryer with integrated thermal storage for drying apple slices efficiently, offering a practical solution for sustainable post-harvest management. The dryer features a single-pass solar collector and a 16.5 kg capacity drying chamber embedded with paraffin wax as a thermal energy storage material to maintain consistent heat during the drying process. This innovative design achieved a thermal efficiency 11 ± 0.2% higher than conventional solar dryers and reduced drying time by 40 ± 2.1%, aligning with the goals of energy-efficient post-harvest practices. Compared to open sun drying and thin-layer drying, the solar dryer with thermal storage (SDTS) preserved nutrients more effectively, with total sugar content reaching 64.85 ± 3.50% and fiber content at 12.50 ± 0.75%, the highest among all methods. Moreover, SDTS-dried apple slices exhibited greater total phenolic content (TPC) and antioxidant activity, underscoring superior product quality. The integration of thermal storage minimized drying inconsistencies, reducing post-harvest losses and ensuring nutrient retention. Statistical models were developed to predict moisture ratios accurately, validated through chi-square and root mean square error analysis. This enhanced dryer demonstrates improved efficiency and reliability, making it a scalable, sustainable solution for small-scale fruit farmers, ultimately addressing critical post-harvest management challenges.

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ABSTRACT Oxygen vacancies in magnetic materials are pivotal in tailoring their magnetic properties, offering a versatile pathway to manipulate their performance. This study focuses on the impact of oxygen vacancies on the magnetic properties of EuTiO3 (ETO) thin films, demonstrating how these vacancies can induce ferromagnetism, a property not typically observed in its stoichiometric form. By controlling the background oxygen pressure during fabrication, we obtained ETO thin films with varying concentrations of oxygen vacancies and investigated their magnetic behavior. The results reveal that the manipulation of oxygen vacancies significantly influences the magnetic properties of ETO thin films. Films grown under low oxygen pressure exhibit a peak in the Curie temperature (Tc) around 4.1 K, indicating a transition to a ferromagnetic state. In contrast, films grown under high oxygen pressure show a Tc peak at approximately 2.5 K, suggesting an antiferromagnetic state. The control over oxygen vacancies provides a profound impact on the magnetic landscape of ETO, making it a critical handle in the engineering of magnetic properties for various applications, including multiferroic devices.

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ABSTRACT The performance of polymer-based nano iron composites reinforced with natural fibers and nanoparticles is investigated in this work with the aim of enhancing their mechanical electrical and water-absorbing properties for a variety of applications. System 1 (PLA with nano iron particles) System 2 (PLA with natural fillers) and System 3 (PLA with both natural fillers and nano iron particles) are the three composite systems that were developed. Mechanical performance assessment tests including tensile compression and bending tests as well as electrical conductivity and water absorption morphological analysis using SEM and EDAX were all conducted. According to the results System 3 which combines natural fillers with nano iron showed superior tensile and flexural strength because of improved filler dispersion and improved filler-matrix bonding. The creation of a conductive network by nano iron was responsible for System 2s highest electrical conductivity (340 µS/cm). Compression testing showed that Systems 2 and 3 were stronger because there were fewer voids and cracks spreading. System 2 did however exhibit a high water absorption rate of 20% which may indicate durability problems. According to this study adding natural fibers and nanoparticles to PLA composites may produce lightweight incredibly durable multifunctional materials with exciting potential uses in the electronics automotive and construction sectors.

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Abstract In the realm of compression molding of Carbon Fibre Reinforced Composite (CFRC) laminates, pivotal technological challenges related to product quality monitoring are addressed in this study, a multi-source information fusion method based on monitoring feedback is proposed. The study begins with the design of a control system, alongside the establishment of its software and hardware architecture, all of which are rooted in the production line's composition, its processes, and the overarching manufacturing workflow. This paves the way for the refinement and optimization of reliability assessment methods, specifically tailored for monitoring factors and characteristics with functionalization at their core. Then, a higher-order shear deformation theory (HSDT) is proposed based on Iso-Geometric Analysis (IGA), and the static bending, free vibration, and buckling behaviours of CFRC laminates are scrutinized. The narrative culminates under the influence of fluctuating temperature conditions, where the proposed methodology's performance and precision are rigorously validated through an extensive suite of numerical examples. A comparative analysis with theoretical results gleaned from existing literatures yields a harmonious consistency, underscoring the robustness of the approach. The research results of this paper provide theoretical support for the quality analysis of carbon fiber reinforced composite molding process.

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ABSTRACT Self-Compacting Concrete (SCC) plays a vital role in the construction sector globally due to the requirements of tall and complex congested structures. River sand is one of the natural key ingredients that has high demand due to the expansion of cities and the growth of population. To overcome this problem researchers from various countries are attempting for alternative materials. In this research, Sugarcane Bagasse Ash Aggregates (SBAA) and Rice Husk Ash Aggregates (RHAA) were utilized to partially substitute of fine aggregate in SCC. The suitability of SBAA and RHAA in SCC is assessed by microstructural characterization and mechanical properties. Three groups of SCC mixes were prepared. Gropup-1 mix contains RHAA about (0%, 5%, 10%, 15% and 20%), Group-2 mix contains SBAA (0%, 5%, 10%, 15% and 20%) and Group-3 mix contains blended RHAA SBAA (each 5%, 10%, 15% and 20%). EFNARC guidelines were used for mix design and assess the rheological characteristics. In all the groups of SCC mixes, 10% replacement of SBAA and RHAA shows significant results. This investigations shows that the blended ash aggregates can be replaced with fine aggregate and considerably can reduce the demand of river sand.

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ABSTRACT This study investigated the optimal calcination conditions for obtaining β-hemihydrates from the “cocadinha” and “rapadura” varieties of gypsum, which are used in plaster production in the Araripe gypsum Pole. The samples were characterized using techniques such as scanning electron microscopy (SEM), thermogravimetric analysis (TGA), derivative thermogravimetry (DTG), and X-ray diffraction (XRD). The analyses indicated a similarity in the morphology of the samples. During calcination in a static furnace, mass losses ranging from 12.8% to 19.8% were observed. The study identified thermal events and crystalline phases as the calcination time and temperature varied. Complete conversion of the dihydrate phase into β-hemihydrate was achieved at 180 °C for 2 h, while partial conversion occurred at 160 °C for 2 h. The Rietveld refinement was successful, with χ2 values close to 1 and R indicators below 10% for all analyzed samples. Based on the experimental results, the study identified optimal calcination conditions for producing hemihydrate plaster from the cocadinha and rapadura gypsum varieties, achieving consistent hardness and compressive strength in accordance with NBR 13.207 standards. Both varieties demonstrated setting times comparable to industrial benchmarks after 2 hours or more of calcination at 160 °C and 180 °C. These findings suggest the potential for process optimization, reducing energy consumption while maintaining product quality.

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ABSTRACT Aluminium alloys find diverse applications in building construction. Specifically, C-profiles being used as various structural elements in the building. Providing Edge stiffeners in the C-profile leads to increase the load carrying capacity. Limited research is available on compression behaviour c-profile with edge stiffeners. Hence, this article aims to study the behaviour of a Finite Element Analysis of aluminium alloy stiffened edge C profiles subjected to axial compression. Two different aluminium alloy materials, namely 6061-T6, and 6063-T5 were investigated. Finite element models were developed and results, including ultimate load, failure modes, and load vs. axial shortening curves, were verified against existing test data. A comprehensive parametric study was carried out based on the verified finite element models, involving variation in the orientation of the edge stiffener, column length, and section thickness. A total of 144 parametric results were compared with the design strengths calculated from Euro code 9.

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ABSTRACT This study investigates the synthesis and application of a novel ZnO-polyacrylamide nanocomposite as a performance-enhancing additive for water-based drilling fluids. The nanocomposite was successfully synthesized through a modified solution polymerization method, producing uniformly dispersed spherical particles ranging from 35 to 45 nm as confirmed by FESEM analysis. XRD characterization revealed distinctive peaks at 2θ values of 31.7°, 34.4°, 36.2°, 47.5°, and 56.6°, confirming the hexagonal wurtzite structure of ZnO, while FTIR spectroscopy demonstrated effective integration through characteristic absorption bands at 3435 cm−1, 2924 cm−1, and 1656 cm−1. Systematic evaluation of drilling fluid properties showed that incorporation of the nanocomposite at concentrations between 0.1−1.0% (w/v) significantly enhanced performance parameters. The optimal concentration of 0.7 wt% achieved a 43.8% reduction in API fluid loss, decreased filter cake permeability by 62.4%, and maintained rheological stability with viscosity reduction rate of 0.15 cP/°C compared to 0.28 cP/°C for the base fluid. HTHP testing at 150°C and 500 psi demonstrated enhanced thermal stability with 35.5% reduction in filtrate volume. Shale inhibition studies revealed improved performance through both linear swelling tests and recovery measurements, with recovery rates remaining stable even after secondary exposure to fresh water. The research demonstrates that the integration of ZnO nanoparticles within a polyacrylamide matrix creates a synergistic effect that addresses multiple drilling fluid challenges simultaneously, offering potential applications in high-temperature wells and reactive shale formations.

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ABSTRACT The flow and heat transfer characteristics of methane under supercritical pressure are crucial for storing and transporting liquefied natural gas. This study employs a renormalization group k-ε model with enhanced wall functions to investigate methane’s mixed convective heat transfer in pipes with different diameters, revealing two heat transfer enhancement characteristics. When the channel diameter changes, the mechanisms influencing heat transfer performance differ, resulting in peaks of varying nature in the heat transfer curve. The enhanced heat transfer mechanisms are explained in detail by comparing the effects of buoyancy and specific heat capacity at various temperatures. Further analysis reveals that increasing heat flux leads to the superposition of buoyancy and specific heat effects, producing a single peak in the heat transfer coefficient. The relative variations of the Nusselt number and synergy angle explain the phenomenon of heat transfer enhancement superposition. A new criterion for enhanced heat transfer due to buoyancy is proposed, Bo* = 4.21 × 10−8, which can be used to evaluate the impact of buoyancy on the enhanced heat transfer.

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ABSTRACT Materials recycling presents a compelling economic case for waste disposal sites and the conservation of natural resources. This study delves into the substitution of cement with varying percentages of marble waste (0%, 10%, 20%, 30%, 40% and 50%). The water-to-binder ratio is consistently set at 0.44 for all mixes. Chemical admixtures such as superplasticizers or viscosity agents are frequently added to the mortar to improve its flow and strength. We conducted mini-slump flow and rheometer tests to assess the fresh mixes' rheological properties, as well as tests to measure the compressive and tensile strength of the mixes. The findings indicate that including marble powder enhances the mechanical properties of self-compacting mortar. A substantial 29% enhancement was achieved for a mixture incorporating 30% marble waste. The most favorable rheological properties, including slump flow, yield stress, and superior mechanical performance in compressive and tensile strength, were observed in the mix containing 30% marble powder waste. Furthermore, the investigation showed that the self-compacting mortar with a yield stress of 0.98 MPa at a 50% MW replacement rate and a viscosity of 1.4 Pa.S can achieve a slump flow of 25–31 cm. These findings illustrate marble waste potential as a valuable addition to self-compacting mortar (SCM) manufacturing, delivering improved performance and structural integrity. However, specific application scenarios and long-term endurance restrictions require further investigation. Practical effects include the possibility of developing inventive, sustainable, and economic SCM compositions, which will help to advance construction practices and sustainability. The social ramifications include reducing environmental impact and increasing resource efficiency in the construction industry.

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ABSTRACT Significant risks of corrosion and wear are associated with agricultural equipment’s continuous exposure to fertilizers harsh chemicals and moisture. These chemicals hasten the deterioration of metal components thereby decreasing the machinery’s operational lifespan and leading to physical harm such as surface cracks and holes. Utilizing efficient corrosion protection methods is crucial to lessening these adverse consequences. In order to solve this, the current study investigates a corrosion prevention technique that involves coating copper with stearic acid to produce a superhydrophobic surface. To create this protective coating copper samples were cleaned and then left to soak for 72 hours at room temperature in a stearic acid solution. Utilizing energy-dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM) post-treatment analysis of the copper surfaces revealed a notable improvement in corrosion and wear resistance. The development of a hydrophobic microstructure was validated by SEM images and the successful deposition of the stearic acid was indicated by an 88 percent increase in carbon content in the EDX results. The high anti-wettability of the coating was demonstrated by performance tests which included water bouncing jetting and self-cleaning assessments. This technique also offers an eco-friendly corrosion prevention solution because stearic acid comes from natural sources. The results highlight the potential of stearic acid coatings to decrease metal loss from corrosion and increase the useful life and efficiency of agricultural equipment.

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ABSTRACT This study investigates developing and characterizing a novel hybrid composite reinforced with Prosopis juliflora bark nanoparticles, Raffia fiber, and glass fiber embedded in a polyester resin matrix. The composite was fabricated using the resin transfer molding technique to ensure uniform fiber impregnation and nanoparticle dispersion. Mechanical tests revealed a tensile strength of 165 MPa, a flexural strength of 388 MPa, an impact strength of 4 J, a Shore D hardness of 42 RHN, and an interlaminar shear strength of 24 N/mm2, marking significant improvements of 35–40%, 25–30%, and 20% in tensile, flexural, and impact properties, respectively, compared to conventional composites. Thermogravimetric analysis showed enhanced thermal stability, with decomposition temperatures increasing by 15–20% due to the thermal shielding effect of nanoparticles. Scanning Electron Microscopy (SEM) confirmed uniform nanoparticle dispersion and strong fiber-matrix adhesion, contributing to the composite’s superior performance. The novelty of this research lies in the synergistic combination of natural and synthetic fibers with multifunctional nanoparticles, which optimizes mechanical and thermal properties while maintaining environmental sustainability. These hybrid composites, with their significant mechanical and thermal improvements, are a scientific achievement and a cost-effective solution for high-performance applications in automotive, structural, and aerospace industries, offering a sustainable alternative to traditional materials.

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ABSTRACT This study examines the impact of adding fly ash and metakaolin to different concrete mixes on workability, strength, and durability. Results showed that conventional concrete had a slump value of 101 mm. In contrast, the mix with 10% fly ash and 10% metakaolin achieved a slump value of 102 mm, suggesting improved workability with this combination. The compressive strength for this mix was notably the highest at 35.34 MPa after 28 days, demonstrating the effectiveness of the combination in improving strength. The split tensile strength and flexural strength also showed significant improvements, with values of 55.34 MPa and 4.47 MPa, respectively. Furthermore, water absorption tests revealed a saturated water absorption of 1.99% and porosity of 2.85% for the optimal mix, suggesting enhanced durability due to reduced permeability. These findings highlight that the strategic use of fly ash and metakaolin not only optimizes the mechanical properties of concrete but also enhances its durability characteristics, making the 10% fly ash and 10% metakaolin blend a promising alternative for sustainable concrete formulations in construction applications.

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ABSTRACT In this study, we show how to use Metal Inert Gas butt-welding to its full potential by optimising the geometry of the weld beads. The poor quality of welding, which is affected by several factors during the welding process, is a common cause of joint failure. Along with the rapid advancement of computer and automated technologies, new statistical methodologies for optimization and modeling have been developed. Due to them, traditional trial-and-error-based studies for efficiency and quality are no longer necessary. Experimental methods were developed to elucidate the numerical expression between the welding process parameters and the output variable. It Briefly outline the criteria used for comparison (e.g., surface finish, tensile strength, and hardness) and state the key finding, such as how specific process parameters (e.g., temperature and rolling speed) achieved optimal performance metrics. These parameters included welding current, welding speed, and arc voltage. Then, the weld bead geometry's performance was evaluated using a Taguchi technique, which takes into account bead height and bead width. We employ an Orthogonal array of L9 and analysis of variance (ANOVA) to learn about and enhance the welding properties of hot rolled carbon steel material. Confirming its efficacy in the analysis of weld bead height and bead width, conformations tests were conducted to compare predicted values with experimental values.

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ABSTRACT This research delves into the impact of incorporating nanomaterials into reinforced concrete beams on their corrosion resistance and mechanical properties. Various combinations of nanomaterials, such as nanosilica (NS) and nanoclay (NC), are introduced into the cement matrix to examine their effects on fresh and hardened concrete. Testing is conducted on specimens including cubes, prisms, and beams at intervals of 7, 14, and 28 days to assess compressive and flexural strengths. The aim is to ascertain how different percentages of nanomaterial replacements for cement influence the mechanical properties of concrete. The properties comparable to the conventional concrete and 20% of nano silica addition of the concrete. Additionally, the study investigates the corrosion resistance of reinforced concrete beams with nanomaterials. The specimens tested such as rapid chloride permeability testing, half-cell potential testing, and resistivity testing are employed to determine the corrosion resistance of the beams. It is anticipated that certain combinations of nanomaterials will enhance the mechanical properties of the concrete, thereby improving its resistance to corrosion. The findings of this research hold potential for enhancing the durability and longevity of reinforced concrete structures in various applications.

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ABSTRACT This study explores the use of Ground Nut Shell Ash (GNSA), Cashew Nut Shell Ash (CNSA), and Discarded Nylon Fiber (DNF) as supplementary materials in cement concrete to enhance sustainability. Mechanical properties such as compressive, tensile, and flexural strengths were analyzed for concrete mixtures with varying proportions of these materials. Results indicate that the optimal blend increased compressive strength by 15%, tensile strength by 10%, and flexural strength by 12% compared to conventional concrete. Improvements are attributed to the pozzolanic activity of the ashes and the reinforcing effect of nylon fibers. The compressive strength also showed significant gains at 7, 28, and 56 days of curing. Utilizing these waste products promotes environmental sustainability and reduces waste. This research demonstrates the potential of agro-industrial by-products and recycled fibers to produce eco-friendly concrete with enhanced mechanical properties. Further studies are recommended to assess the long-term durability and environmental impacts of these innovative composites.

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Abstract This study presents an improved technique that uses many machine-learning models to estimate the compressive strength of concrete. The goal of the project is to increase the precision of strength predictions based on the age and composition of concrete mixes. Cement, fly ash, water, superplasticizer, coarse and fine aggregate, and sample age are among the materials. Megapascals (MPa) are used to quantify compressive strength. To determine the connections between mix proportions, age, and strength, a variety of blends were examined. Machine learning techniques including Random Forest, XGBoost, AdaBoost, Bagging, Support Vector Regression, and Linear Regression were used. The efficiency of the model was assessed using performance indicators such as accuracy, R-squared (R2), Mean Absolute Error (MAE), and Mean Squared Error (MSE). With an MAE of 2.2, MSE of 10.5, R2 of 0.94, MAPE of 8.5, RMSE of 3.25, and accuracy of 0.92, XGBoost (optimized) performed the best. This model performed noticeably better than others, highlighting how machine learning may improve predictions of compressive strength and optimize the composition of concrete, thus promoting the fields of materials science and civil engineering.

Abstract in English:

ABSTRACT The ability of the electrical steels to amplify an externally applied magnetic field is due to a strong texture induced during secondary recrystallization, the step in which grains with Goss orientation nucleate in the primary matrix. At this stage, normal grain growth is inhibited by a scattering of precipitated particles. The main objective of this research was to investigate the effect of stretching during the annealing and decarbonizing treatment on the magnetic properties of grain-oriented electrical steels with 3% Si. The study subjected grain-oriented electrical steel samples to heat treatment simultaneously to different tensile stresses. After the heat treatment, the samples were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The best results, in terms of core losses, were obtained for the sample treated without stretching. The presence and size of MnS and AlN precipitates were also found to significantly influence the magnetic properties. These results focused on the importance of controlling stretching during annealing to optimize the magnetic performance of grain-oriented electrical steels for applications in transformers and generators.

Abstract in English:

Abstract This study addresses the issue of cracking in WC/Ni60 cladded layers with high WC content. The effects of different WC contents on the formation quality, microstructure, and microhardness of WC/Ni15 cladded layers, as well as the influence of various nickel alloys (Ni15, Ni35, and Ni60) on Ni+20% WC cladded layers, were investigated. The results show that as the WC content increases, the microstructure of WC/Ni15 cladded layers becomes denser and finer, with the formation of W-rich compounds and carbides such as Ni2W4C and W2C, resulting in an increase in hardness. When the WC mass fraction reaches 50%, cracks and larger pores appear in the WC/Ni15 cladded layer, and the higher viscosity of the melt pool causes W-rich compounds to be uniformly distributed throughout the layer. At a WC mass fraction of 20%, the pores in the cross-sections of WC/Ni15, WC/Ni35, and WC/Ni60 cladded layers decrease sequentially. The microstructure transitions from cellular to dendritic, the dendrite spacing decreases, and hardness increases, with W-rich compounds mainly concentrated at the top of the cladded layer. In the Ni60+20% WC cladded layer, the increase in borides leads to the formation of cracks. The Ni15+40% WC cladded layer, however, does not exhibit cracks and has a hardness comparable to that of the Ni60+20% WC cladded layer. Under the same conditions, adding a high content of WC particles to Ni15 powder results in a crack-free cladded layer with higher hardness, making it more favorable for industrial applications of WC/Ni cladded layers.

Abstract in English:

ABSTRACT The hydrophobicity of a surface gives it peculiar properties, making it non-sticky and more resistant to corrosion. Stearic acid (SA) is saturated carboxylic acid that has C18 in molecular structure. The longer the carbon chains of fatty acids in a coating, the lower its solubility in water and consequently the greater its superhydrophobic characteristic. This study is of fundamental importance because it presents the potential for technology transfer since the methods used in this study, both for manufacturing and deposition of coatings, are simple and can be applied industrially, and also use low-cost products such as SA. In this sense, the objective of this study is to evaluate the corrosion resistance of the 5052 aluminum alloy when coated with superhydrophobic films based on stearic acid. Stearic acid (SA) in a 1% ethanolic solution was deposited using dip-coating. Aluminum substrate coated with SA was tested with three variations of surface morphology: as received (L), sanded (#) and sandblasted (J). The morphology of the substrates was analyzed by scanning electron microscopy (SEM), and the chemical composition of the coating/substrates, by energy dispersive spectroscopy (EDS). Contact angle (CA) analysis was performed to verify the hydrophobicity provided by the coating. Corrosion resistance was assessed using electrochemical impedance spectroscopy (EIS) and salt spray testing. The blasted surface yielded the best contact angles, with a mean angle of 158.9°. The superhydrophobic sample showed better corrosion resistance than the other substrates, which had contact angles below 150°.

Abstract in Portuguese:

RESUMO A crescente eletrificação global e a necessidade da redução das emissões de CO2 impulsiona o aprimoramento das baterias de chumbo-ácido, ampliando seu papel tanto na mobilidade veicular quanto na infraestrutura de armazenamento de energia. Este estudo propõe uma nova abordagem dinâmica para a caracterização eletroquímica dos produtos de corrosão em ligas de chumbo, dividindo a análise em duas fases: (i) formação da camada de corrosão e (ii) consolidação dessa camada. Foram realizadas voltametrias cíclicas e espectroscopias de impedância eletroquímica em amostras de chumbo puro (Pb) e liga Pb1,5Sn, em solução de H2SO4 5M a 25°C, com varredura de +1,3V a +2,2V. Os ensaios evidenciaram diferenças na cinética de corrosão e na estabilidade da camada de PbO2 formada. A abordagem dinâmica mostrou que conclusões podem divergir dependendo do ciclo analisado, destacando a importância de considerar a evolução temporal das reações. Os resultados indicam que a liga Pb1,5Sn apresentou maior resistência à corrosão ao longo dos ciclos, evidenciada pelo aumento da impedância eletroquímica e da estabilidade da camada de PbO2. A metodologia proposta aprimora a interpretação dos fenômenos eletroquímicos, sendo útil para otimizar a seleção de materiais em baterias de chumbo-ácido.

Abstract in English:

ABSTRACT The growing global electrification drives the improvement of lead-acid batteries, expanding their role in both vehicular mobility and energy storage infrastructure. This study proposes a new dynamic approach for the electrochemical characterization of corrosion products in lead alloys, dividing the analysis into two phases: (i) formation of the corrosion layer and (ii) consolidation of this layer. Cyclic voltammetry and electrochemical impedance spectroscopy were performed on samples of pure lead (Pb) and Pb1.5Sn alloy in 5M H2SO4 solution at 25°C, with a scan range of +1.3V to +2.2V. The tests revealed differences in the corrosion kinetics and stability of the PbO2 layer formed. The dynamic approach showed that conclusions can vary depending on the cycle analyzed, highlighting the importance of considering the temporal evolution of reactions. The results indicate that the Pb1.5Sn alloy exhibited higher corrosion resistance throughout the cycles, as evidenced by the increase in electrochemical impedance and the stability of the PbO2 layer. The proposed methodology enhances the interpretation of electrochemical phenomena, proving useful for optimizing material selection in lead-acid batteries.

Abstract in English:

ABSTRACT Fibers for e-waste management are emerging as sustainable materials, often derived from natural or recycled sources, to replace non-biodegradable components in electronic products. This study investigates the development and characterization of carbon fiber-reinforced composites derived from electronic polymer toy waste (EPTW), emphasizing sustainability and material reutilization. The primary objective is to fabricate and evaluate composite materials with varying compositions of EPTW (CF-0EPTW, CF-5EPTW, CF-10EPTW, CF-15EPTW, CF-20EPTW) to assess their mechanical, thermal, and morphological properties. The polymer matrix and carbon fibers were meticulously processed and mixed with electronic toy waste particles using precise ratios and advanced fabrication techniques. Materials were tested for tensile, compressive, flexural, and impact strengths under controlled conditions, adhering to ASTM standards. The results were analyzed using Response Surface Methodology (RSM) to optimize process parameters and identify trends. A comparative analysis between experimental outcomes and RSM predictions demonstrated excellent correlation, validating RSM as a robust tool for optimizing material properties. Morphological characterization, including Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), and Energy Dispersive X-ray Analysis (EDAX), provided detailed insights into the composites’ microstructural integrity and elemental composition. The results confirm that CF-0EPTW exhibits superior mechanical performance and thermal stability, while RSM efficiently predicts composite behavior, surpassing experimental variations in accuracy.

Abstract in English:

ABSTRACT This current work, studied the effects of nano silicon nitride (n-Si3N4) particles incorporated with AA8050 matrix using a stir-casting method. Physical characteristics including density and porosity were measured. The mechanical characteristics including the impact strength (IS), ultimate tensile strength (UTS), elongation (El), and Vickers hardness (HV) were evaluated according to the standards. Metallurgical characteristics including Scanning Electron Microscopy (SEM), Energy dispersive spectroscopy (EDS) and X-ray diffraction analysis (XRD) examined the synthesized composites. The theoretical density rise for 3.5% reinforcement is capped at 1.6%, while the experimental density drop is 3.1%. Also incorporating n-Si3N4 into the matrix significantly increased the UTS, HV, and IS with a percentage of 11.04%, 25.88%, 29.88% accordingly. SEM of AA8050 Composites revealed a dispersion of n-Si3N4 particles in the AA8050. When analyzing the EDS of AA8050 Composites, a high-intensity peak indicates that the composites have a high rate of Al by weight. In XRD to all appearances, the Al phase encloses the n-Si3N4 particles.

Abstract in English:

ABSTRACT The intent of the existing research was to examine the tribological characteristics of AA2024/Aluminium Nitride (AlN), synthesized through stir casting route (SCR). The composite specimens were developed at various amounts of (0, 5, 10 and 15 wt.%) AlN particles (P). The pin-on-disc (POD) wear tester was used to predict the wear of the proposed Metal Matrix Composites (MMCs). The experiments were performed by considering three variables such as load (LD), sliding velocity (SV) and sliding distance (SD). Taguchi procedure has been applied to propose the plan of experiments and tests were executed as per L16 orthogonal array (OA) layout. Signal-to-noise (S/N) ratio were used to establish the optimal site of variables in order to obtain lesser wear rate (WR) and co-efficient of friction (CF) for the tested composites. The impact of parameters on WR and CF were analyzed by analysis of variance (ANOVA). The examinations found that the ‘LD’ has more dominant factor on WR with a contribution of 75.86%, and the wt.% of P has more influence on CF with a contribution of 75.06%, respectively.

Abstract in English:

ABSTRACT Aluminium Alloy Hybrid Metal Matrix Composites (AAHMMCs) have been utilized in automotive, marine, military and aerospace applications due to their high strength-to-weight ratio, microhardness, tensile, impact, and compressive strength, along with superior tribological properties. This study focused on optimizing ultrasonic-assisted stir casting of AA7075/WC/SiC Hybrid Metal Matrix Composites (HMMCs) by varying the wt.% of WC and SiC (6, 8, and 10), melting temperature (700, 750, and 800°C), stirring time (5, 10, and 15 min), and stirring speed (200, 225, and 250 rpm), while keeping ultrasonic parameters constant. The inclusion of 0.25 and 0.5 wt.% Scandium increased microhardness by 18% due to the Hall-Petch effect and Al3Sc precipitates, which strengthened the material. Ultrasonic assistance improved grain refinement and uniform particle distribution. The optimal process parameters were determined as a 750°C melting temperature, 250 rpm stirring speed, 5 min stirring time, and 8 wt.% WC+SiC. Aging at 300°C improved microhardness (by 15%), tensile strength (by 14.3%), compressive strength (by 12.4%), and wear resistance (by 51%) due to Mg2Si and Mg2Zn precipitates. Aging at 400°C increased impact strength by 59%, attributed to Al2Cu precipitate.

Abstract in English:

ABSTRACT This study explores the impact of incorporating recycled brick sand as a partial replacement for natural sand on the mechanical and transport properties of roller-compacted concrete (RCC) for dam construction. RCC mixtures were prepared with varying brick sand replacement levels and two different water/cement (W/C) ratios with cement dosages. Workability was assessed using the Vebe apparatus, while compressive and tensile strengths were evaluated at different ages. Additionally, porosity, water permeability, capillary absorption, and thermal conductivity were measured over time. Microstructural was characterized using Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). The results indicate that brick sand has minimal influence on the RCC Vebe time. Compressive strength improves with brick sand incorporation, particularly in the long term, with an optimal substitution level of 25%. However, porosity and sorptivity increase at higher replacement levels, negatively affecting durability. Water permeability and thermal conductivity decrease with greater brick sand content, enhancing RCC’s resistance to fluid penetration and thermal properties. Variations in cement dosage and W/C ratio had a limited impact on the brick sand RCC performance. These findings suggest that partial replacement of natural sand with brick sand can enhance RCC properties while promoting sustainable material reuse in dam construction.

Abstract in English:

ABSTRACT The fabrication of silane-based hydrophobic surfaces depends on factors such as organic substitution reactions, the extension of the surface area being covered, and the distribution of hydroxyl groups on the surface area to increase the anchoring of the coating and consequently improve the corrosion resistance of the metal. In this sense, the objective of the present work is to evaluate the corrosion resistance of the 5052 aluminum alloy was evaluated by the development of hydrophobic surfaces using silanes. Nanoparticles (NPTs) of tetraethoxysilane silane (TEOS) were used to provide morphological roughness for the studied substrates. TEOS and vinyltriethoxysilane (VTES) NPTs were combined to verify the synergistic effect occurring when obtaining angles greater than 150°. The fabrication of the TEOS NPT solution was based on propanone and sodium hydroxide, whereas for the mixing of the VTES solution, ethanol, water and acetic acid were used. The silane deposition was carried out using dip coating and electro-assisted techniques. The aluminum substrate with the silane coatings was tested using two variations of surface morphology, as-received (L) and blasted (J). Substrate composition was verified by X-ray fluorescence (XRF). Contact angle (CA) analysis was performed to evaluate the hydrophobicity provided by the coating. The morphology of the substrates was analyzed by TEM (transmission electron microscopy). Corrosion resistance was verified by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The results obtained from the VTES coating tests verified that a potential of −1.2 V, combined with the blasted substrate, provided lower wettability. However, the results of the electrochemical tests showed that smooth surfaces with film deposition and potentials of −1.2 V and −0.8 V had more corrosion resistance compared to the other analyzed samples.

Abstract in Portuguese:

RESUMO O fosfogesso (PG) é um dos principais resíduos gerados na produção de fertilizantes fosfatados. É composto majoritariamente por sulfato de cálcio di-hidratado (CaSO4·2H2O), mas pode conter impurezas como ácido sulfúrico (H2SO4) e ácido fosfórico (H3PO4). Devido ao risco ambiental associado à sua geração e composição química, uma estratégia de manejo é utilizá-lo como fonte suplementar de sulfato na produção de cimento. Contudo, as impurezas do FG representam um obstáculo, visto que ainda não há clareza sobre seu comportamento a longo prazo na hidratação do cimento. Desse modo, analisou-se os efeitos das impurezas do FG na hidratação do cimento utilizando modelagem termodinâmica. Simulou-se pastas de cimento CP I, CP II e CP V com até 5% de H2SO4 e H3PO4. Empregou-se o programa de modelagem geoquímica GEM-Selektor baseado na minimização da energia de Gibbs para análise da composição de fases em 1000 dias. A análise mostra que o aumento de H2SO4 afetou a formação da etringita, monossulfato e portlandita, enquanto a adição de H3PO4 retardou a formação da portlandita e C-S-H. Esse efeito deve-se à reação dos íons fosfato com cálcio formando fosfato de cálcio, principalmente no CP II. Portanto, a modelagem termodinâmica pode auxiliar nas limitações técnicas experimentais a longo prazo de materiais cimentícios contendo FG.

Abstract in English:

ABSTRACT Phosphogypsum (PG) is one of the main residues from the production of phosphate fertilizers. It is mostly composed of calcium sulphate dihydrate (CaSO4·2H2O) and contains impurities such as sulphuric acid (H2SO4) and phosphoric acid (H3PO4). Due to the environmental risk associated with its generation and chemical composition, one management strategy is to use it as a supplementary source of sulfate in cement production. However, the impurities in FG represent an obstacle, since there is still no clarity on its long-term behavior in cement hydration. Therefore, the effects of PG impurities on cement hydration were analyzed using thermodynamic modeling. CP I, CP II and CP V cement pastes with up to 5% H2SO4 and H3PO4 were simulated. The GEM-Selektor geochemical modeling program based on Gibbs energy minimization was used to analyze the phase composition over 1000 days. The analysis shows that the increase in H2SO4 affected the formation of ettringite, monosulfate and portlandite, while the addition of H3PO4 delayed the formation of portlandite and C-S-H. This effect is due to the reaction of phosphate ions with calcium to form calcium phosphate, especially in CP II. Therefore, thermodynamic modeling can help with the long-term experimental technical limitations of cementitious materials containing PG.

Abstract in Portuguese:

RESUMO A usinagem de cerâmica avançada pré-sinterizada é uma técnica empregada para melhorar a resistência do compacto, facilitando a usinabilidade em comparação com a cerâmica em verde (frágil) e a cerâmica sinterizada (extremamente dura). Diversos fatores influenciam esse processo, incluindo a temperatura de pré-sinterização, os parâmetros de usinagem, o método de compactação e o tipo de material cerâmico. O presente trabalho tem como objetivo avaliar a influência de diferentes temperaturas de pré-sinterização no processo de torneamento de cerâmicas avançadas, buscando identificar a condição ideal para otimizar a fabricação de componentes cerâmicos. Para tanto, foi utilizada uma bancada de usinagem equipada com sistema de monitoramento da força de avanço por meio de célula de carga. Foram analisadas as propriedades de densidade, retração linear, força de avanço, dureza e acabamento superficial (pré-sinterizado e sinterizado) em quatro temperaturas: 950°C, 1000°C, 1050°C e 1100°C. Os resultados mostraram que o aumento da temperatura de pré-sinterização resultou em maior dureza e maior força de avanço. Em relação ao acabamento superficial, observou-se maior rugosidade para temperaturas superiores a 1000°C. As análises indicam que a temperatura de 950°C é a mais adequada para a pré-sinterização da cerâmica de alumina, pois a usinagem nessa temperatura apresentou a menor dureza e força de avanço, reduzindo o desgaste da ferramenta de corte e, consequentemente, os custos de fabricação. Além disso, não se observou uma diferença significativa no tamanho de grão entre as amostras pré-sinterizadas em diferentes temperaturas.

Abstract in English:

ABSTRACT The machining of pre-sintered advanced ceramics is a technique used to enhance the strength of the compact, facilitating machinability compared to green ceramics (brittle) and fully sintered ceramics (extremely hard). Several factors influence this process, including pre-sintering temperature, machining parameters, compaction method, and ceramic material type. This study aims to evaluate the influence of different pre-sintering temperatures on the turning process of advanced ceramics, seeking to identify the optimal condition for optimizing the manufacturing of ceramic components. A machining setup equipped with a feed force monitoring system using a load cell was employed. The analyzed properties included density, linear shrinkage, feed force, hardness, and surface finish (both pre-sintered and sintered) at four pre-sintering temperatures: 950°C, 1000°C, 1050°C, and 1100°C. The results indicated that increasing the pre-sintering temperature led to higher hardness and greater feed force. Regarding surface finish, higher roughness was observed at temperatures above 1000°C. The analysis suggests that a pre-sintering temperature of 950°C is the most suitable for alumina ceramics, as machining at this temperature resulted in the lowest hardness and feed force, reducing cutting tool wear and, consequently, manufacturing costs. Furthermore, no significant difference in grain size was observed among the samples pre-sintered at different temperatures.

Abstract in English:

ABSTRACT Industries worldwide seek sustainable, high-strength bio-composites to reduce carbon footprint and replace synthetic materials. This research enhances natural fiber-based composites, ensuring lightweight, cost-effective, and eco-friendly alternatives. It supports green manufacturing and sustainable engineering, promoting a shift away from fossil-based materials. This study aims to optimize the mechanical properties of nano-hybrid bio-composites reinforced with Holoptelea integrifolia fibers, Helicteres isora fibers, and graphene nanosheets within a polypropylene matrix. Using the Box-Behnken design and Response Surface Methodology (RSM), the effects of fiber and graphene composition on tensile, flexural and impact strength were analyzed. The Multi-Objective Particle Swarm Optimization (MOPSO) approach was employed to maximize strength while minimizing composite weight. The optimized composition (15.6721 wt% Holoptelea integrifolia, 15.7198 wt% Helicteres isora, and 0.9307 wt% graphene) achieved a tensile strength of 45.407, flexural strength of 62.0344 MPa and impact strength of 147.119 J/m, demonstrating a significant enhancement. FESEM analysis revealed improved fiber-matrix adhesion, reduced voids, crack path deviation, and fiber bridging mechanisms, which enhanced fracture resistance. These findings support the development of lightweight, high-performance bio-composites, making them ideal for automotive, aerospace, and structural applications where improved strength-to-weight ratios are crucial.

Abstract in English:

ABSTRACT Aluminum matrix composites (AMCs) materials are highly valued in the aerospace and automotive industries for their exceptional characteristics. Zirconium nitride (ZrN) particles were used to reinforce aluminium alloy 6061(AA6061) to enhance the hardness and wear performance. Here the stir casting method is used to create four different composites with different amounts of ZrN particles (6, 12, and 18 wt.%). Using a Brinell hardness tester, the composites bearing the AA6061/12 wt.% ZrN formula achieved the highest recorded hardness value. Accordingly, these AA6061/12 wt.% ZrN composites were subjected to a tribological analysis. We conducted the trials with load (A), sliding speed (B), sliding distance (C) as the wear parameters. In order to determine the best parameter settings for attaining the minimum wear rate (Wr) and friction coefficient (COF), the TOPSIS method was used. Findings indicated that for ‘A’ = 18 N, ‘B’ = 2 m/s, ‘C’ = 1200 m, the COF and minimum Wr were achieved. The Analysis of Variance (ANOVA) data showed that factor ‘A’ contributed 45.43% of the total, with factor ‘B’ coming in second at 18.02%.

Abstract in English:

ABSTRACT This investigation explores the potential of clay brick powder (CBP) as a partial alternative to cement in mortar compositions, concentrating on the effects of the fineness of CBP, which is produced by grinding brick waste for various durations. A range of mortar mixes was analyzed for characteristics including apparent density, porosity, spreadability, ultrasonic pulse velocity (UPV), flexural and compressive strength, and pozzolanic activity index. The analysis reveals that grinding CBP for 60 minutes leads to a mortar spread that exceeds 95% relative to the reference mix. The addition of CBP enhances water absorption and porosity, yet it does not considerably influence the apparent density. Most of the mortar samples demonstrated satisfactory mechanical characteristics, achieving a UPV near 4000 m/s. While replacing 20% of cement with CBP causes a decline in flexural strength, this decrease is mitigated when the specific surface area of CBP is comparable to that of cement. Assessments of environmental and economic factors demonstrate that integrating CBP into cement formulations leads to a marked reduction in energy usage and CO₂ emissions. Specifically, replacing 20% of cement with CBP of varying fineness levels offers significant environmental benefits and economic practicality.

Abstract in English:

ABSTRACT Heat pipes, known for their high efficiency and reliability, are widely used in these systems, but their performance is dependent on the thermal properties of the working fluid. Traditional coolants have limitations, prompting the exploration of nanofluids—suspensions of nanoparticles in base fluids—to enhance thermal performance. This study investigates the effect of silver nanomaterial-based nanofluids with distinct morphologies—nanospheres and nanocubes—along with hybrid compositions incorporating carbon nanotubes, graphene, and quantum dot-metal oxide semiconductors (QD-MOS). Using an experimental approach, the study evaluates heat transfer coefficients, thermal efficiency, and TR across varying concentrations and power inputs. Response Surface Methodology (RSM) and machine learning techniques were employed for optimization. Results indicate that silver nanosphere-based nanofluids enhance the HTC by 38% compared to DI water, while hybrid nanofluids, particularly Ag-Graphene, achieve a 47% improvement. TR is significantly reduced, with nanocube-based fluids performing better at higher power inputs. These findings highlight the potential for tailored nanofluid formulations to enhance heat pipe performance in industrial applications.

Abstract in English:

ABSTRACT The skid resistance parameter is inherent to the concept of road safety. Considering that it is based on micro and macro-texture, their control is essential to prevent or mitigate the occurrence of road accidents. It can be seen that the control of adhesion conditions is carried out after the pavement has been built, so actions corrective rather than preventive. The aim of this research was to investigate aspects that influence the micro and macro-texture of highways in Brazil’s central plateau, to determine the parameters to assess in the mixture, allowing adhesion conditions to be predicted at the design stage. Sand patch and British pendulum tests were carried out to assess macro- and micro-texture and calculate the IFI. The analysis revealed that of the four roads studied, only one met the skid resistance criteria. Although the BPN of DF 440 had an average value below that of DF 003, the condition of adherence was met by the macro-texture, demonstrating that this parameter represents a significant portion of skid resistance. However, there were problems with the gradation of the mixes and the aggregate the area, which is susceptible to polishing, and this analysis should be taken into account when dosing the mixtures.

Abstract in Portuguese:

RESUMO No atual cenário da indústria química, entender profundamente os ativos e seus modos de falha, reduz o tempo de máquina parada, perda de produção e custos de manutenção. O Zircônio 702 aparece como um excelente material para fabricação de componentes de reatores nucleares por conta da resistência à corrosão em altas temperaturas. Esse material também é amplamente utilizado na fabricação de equipamentos de processo que exigem alta resistência a corrosão. Este estudo, abordou os efeitos dos ciclos térmicos consecutivos na microestrutura do material quando submetido a soldas de reparo TIG (Tungstênio Inerte Gás), através do levantamento de aspectos metalográficos e mapeamento de dureza das ZTA (Zonas termicamente afetadas). A ZTA foi identificada como uma região de transição com um aumento gradual de dureza entre 5% e 20%, diretamente relacionado ao aumento da geometria dos grãos de Zircônio, gerados pela mudança morfológica de fase α para fase β em temperatura superior a 863°C. Vale destacar que o resfriamento desigual dessa região causa a formação de estruturas de recristalização martensítica lamelar fina, que possuem boa tenacidade, porém baixa plasticidade. Tais características, apresentam potenciais riscos às soldas repetitivas, principalmente a partir da terceira sequência de reparo, gerando pontos de atenção ao processo de reparo em equipamentos fabricados com o Zircônio 702.

Abstract in English:

ABSTRACT In the current scenario of the chemical industry, deeply understanding assets and their failure modes reduces machine downtime, production loss and maintenance costs. Zirconium 702 appears as an excellent material for manufacturing nuclear reactor components due to its resistance to corrosion at high temperatures. This material is also widely used in the manufacture of process equipment that requires high resistance to corrosion. This study addressed the effects of consecutive thermal cycles on the microstructure of the material when subjected to GTAW (tungsten-gas arc welding), repair welding by surveying metallographic aspects and mapping the hardness of the HAZ (heat-affected zone). The HAZ was identified as a transition region with a gradual increase in hardness between 5% and 20%, directly related to the increase in the geometry of the Zirconium grains, generated by the morphological change from phase α to phase β at temperatures above 863°C. It is worth noting that the uneven cooling of this region causes the formation of fine lamellar martensitic recrystallization structures, which have good toughness but low plasticity. Such characteristics present potential risks to repetitive welding, especially from the third repair sequence onwards, generating points of attention to the repair process in equipment manufactured with Zirconium 702.

Abstract in English:

ABSTRACT This research investigates the influence of electrochemical surface treatment on the mechanical properties of carbon fiber reinforced epoxy composites through systematic parameter optimization and comprehensive characterization. The study established optimal treatment conditions using ammonium bicarbonate electrolyte at 35°C, achieving enhanced interfacial properties through controlled surface modification. Surface characterization revealed the development of hierarchical surface features with primary grooves (0.5–1 μm width) and secondary nano-scale features (50–200 nm), accompanied by a significant increase in surface polarity from 0.20 to 0.41. XPS analysis demonstrated the successful introduction of oxygen-containing functional groups, with hydroxyl, carbonyl, and carboxyl groups showing particular prominence. The modification depth was confined to 200–300 nm, preserving the fiber’s core structure. Mechanical testing revealed substantial improvements in composite performance, evidenced by enhanced load transfer efficiency and a transition in failure modes. The treatment resulted in improved damage initiation stress (from 985 MPa to 1290 MPa) and initial linear modulus (from 135.2 GPa to 149.6 GPa). Additionally, the composite compressive modulus increased from 128.5 ± 3.8 GPa to 142.3 ± 4.2 GPa, representing a 10.7% improvement. Furthermore, surface roughness was significantly enhanced, with the arithmetic mean roughness (Ra) increasing from 8.2 ± 0.5 nm to 45.7 ± 2.3 nm.

Abstract in English:

ABSTRACT A new martensitic low-density steel was designed, and the behavior of austenite grain growth, along with the influence of niobium Nb and V microalloying, was investigated. The results indicated that the austenite grain growth rate in the new martensitic low-density steel was rapid, the austenite grains gradually increased in size with rising austenitizing temperatures, reaching a coarsening temperature of approximately 1000°C. Nb microalloying significantly refined the austenite grain structure and elevated the coarsening temperature to about 1200°C. Nb microalloying resulted in the formation of two size ranges of NbC precipitates: those smaller than 0.3 μm and those larger than 2 μm. The formation of NbC precipitates was the primary reason for the reduced grain growth rate in the Nb microalloyed experimental steel. The NbC precipitate phase hindered the migration of austenite grain boundaries, thereby slowing down the grain growth rate. The NbC precipitates smaller than 0.3 μm dissolved in large quantities when heated above 1200°C, weakening the nailing effect on grain boundaries, which was the main reason for the rapid grain growth observed in the experimental steel. Conversely, the NbC precipitates larger than 2 μm were difficult to eliminate, even when subjected to prolonged heating at 1250°C. The austenite grain growth model for the newly designed martensitic low-density steel was calculated as: D = 1.47 × 103 · t0.097 · e−52423/RT, (900–1150°C) D = 3.45 × 1014 · t0.108 · e−367331/RT, (1200–1250°C).

Abstract in Portuguese:

RESUMO A gelatina tem sido estudada na elaboração de filmes biodegradáveis devido às suas propriedades formadoras de filme, além de sua transparência e flexibilidade. No entanto, sua alta solubilidade em água limita seu uso em ambientes de alta umidade. Nesse contexto, este estudo teve como objetivo avaliar a influência da adição de óleo de pequi, em diferentes proporções, nas propriedades físicas, químicas e mecânicas de filmes poliméricos à base de gelatina. Os filmes foram produzidos por espalhamento em placa, contendo diferentes concentrações de óleo de pequi (0, 0,5% e 1% v/v). Posteriormente, foram caracterizados quanto à espessura, resistência à tração, alongamento, solubilidade em água e FTIR. De modo geral, verificou-se que a adição de óleo do pequi resultou no aumento da opacidade e na espessura (0,061 – 0,079 mm) dos filmes. Em contrapartida, observou-se a redução da resistência à tração (22,75 – 18,51 MPa) e da solubilidade dos filmes de 28,50% para 19,71% com a incorporação do óleo de pequi. No geral, visto que as concentrações de 0,5% e 1% reduziram a solubilidade e a resistência à tração em comparação aos filmes controle, porém, sem diferenças significativas (p 0,05) entre si, conclui-se que a concentração de 0,5% foi a mais adequada.

Abstract in English:

ABSTRACT Gelatin has been studied for the development of biodegradable films due to its film-forming properties, as well as its transparency and flexibility. However, its high-water solubility limits its application in high-humidity environments. In this context, this study aimed to evaluate the influence of pequi oil addition, in different proportions, on the physical, chemical, and mechanical properties of gelatin-based polymeric films. The films were produced using the casting method, incorporating different concentrations of pequi oil (0, 0.5%, and 1% v/v). They were then characterized in terms of thickness, tensile strength, elongation, water solubility, and FTIR analysis. Overall, the addition of pequi oil increased the opacity and thickness (0.061–0.079 mm) of the films. Conversely, it reduced tensile strength (22.75 – 18.51 MPa) and water solubility from 28.50% to 19.71%. In general, since both 0.5% and 1% oil concentrations decreased solubility and tensile strength compared to the control films, but without significant differences (p 0.05) between them, the 0.5% concentration was considered the most suitable.

Abstract in English:

ABSTRACT This study examines the mechanical and microstructural characteristics of 2205 duplex stainless steel (DSS) sheets welded using Autogenous Gas Tungsten Arc Welding (A-GTAW) under optimized conditions. A 2 mm thick DSS plate was butt-welded using a welding current of 100 A, an arc length of 2.4 mm, and a welding speed of 250 mm/s. The welded joint was evaluated for tensile strength, hardness, ductility, bending performance, and formability. The joint exhibited an ultimate tensile strength of 705 MPa, representing a 34% improvement over the base metal (BM), with an elongation of 56.5%. Bending tests confirmed that the joint maintained its structural integrity under severe plastic deformation, with an r/t bending ratio of 2, demonstrating excellent ductility. Microhardness measurements showed a 12.5% increase in hardness in the fusion zone (FZ) relative to the BM, attributed to δ-ferrite and γ-austenite phase transformations. The microstructural analysis revealed the formation of Widmanstätten austenite (WiA), secondary austenite (SA), and partially transformed austenite (PTA) in the FZ, with quantified phase percentages contributing to the enhanced mechanical properties. Fractographic analysis identified ductile failure characterized by dimples, microvoid coalescence, and secondary cracks. The stress-strain curve exhibited a second jump, attributed to strain hardening effects in the welded joint. The Erichsen formability index increased by 10%, indicating superior forming behavior. These results demonstrate that A-GTAW, when applied under carefully controlled parameters, significantly enhances the mechanical performance and structural reliability of 2205 DSS joints, making it a viable technique for critical industrial applications requiring high strength, ductility, and corrosion resistance.

Abstract in Portuguese:

RESUMO A utilização de proteção balística em sistemas construtivos visa assegurar a vida e o patrimônio. Diversos materiais podem ser empregados para tal, dentre eles o CRF (concreto reforçado com fibras). As propriedades do concreto, a espessura do elemento ou sistema, os tipos de reforços e o uso de fibras, entre outros influenciam nesse comportamento. Assim, o presente estudo teve como objetivo avaliar placas de concreto de alta resistência reforçado com fibras de aço. Foram testadas placas com espessuras variadas, a fim de identificar a eficiência de cada dimensão com base na energia de impacto de projéteis provenientes de armas com diferentes calibres. Para avaliação do impacto, foram utilizadas munições dos calibres .22, .38, 9 mm, .357, .44 e 7,62 com energias entre 133 e 3265 J. As placas foram ensaiadas após 42 dias de cura. O concreto foi ensaiado à tração e à compressão. A resistência à tração potencial foi de 11,4 MPa e 105 MPa de resistência à compressão. Os resultados dos testes balísticos apontaram que placas de 50 e de 100 mm de espessura têm níveis de blindagem II-A, II, III-A e III (com impactos de até 3265 J), segundo ABNT NBR 15000 sem ocorrência de transpasse. Apenas as placas de 15 mm de espessura, designadas ao nível de blindagem I, não obtiveram o resultado esperado, apresentando transpasse em uma das placas na energia de 133 J e nas três placas ensaiadas com a energia de 329 J.

Abstract in English:

ABSTRACT The use of ballistic protection in construction systems aims to ensure life and property. Several materials can be used for this purpose, including fiber-reinforced concrete (FRC). The properties of the concrete, the thickness of the element or construction system, the types of reinforcements, and the use of fibers, among others, influence this behavior. This study aimed to evaluate high-strength concrete reinforced with steel fibers plates of varying thicknesses to identify the efficiency of each dimension based on the impact energy of projectiles from weapons with different calibers. To assess the impact, ammunition of calibers .22, .38, 9 mm, .357, .44, and 7.62 were used with energies between 133 and 3265 J. The plates were tested after 42 days of curing. The concrete was tested by tensile and compressive strength. The potential tensile strength was 11.4 MPa and 105 MPa of compressive strength. The results of ballistic tests showed that 50 and 100 mm thick plates have shield levels II-A, II, III-A and III (with impacts of up to 3265 J), according to ABNT NBR 15000, without through-passing. Only the 15 mm plates (for armor level I), did not obtain the expected result, presenting through-passing in one of the plates at an energy of 133 J and in the three plates tested with an energy of 329 J.

Abstract in English:

Abstract Aluminum matrix composites (AMCs) are increasingly vital in aerospace and automotive industries due to their superior strength-to-weight ratio and enhanced mechanical properties. This study explores the mechanical performance of AA8011 aluminum matrix composites reinforced with silicon carbide (SiC) and titanium diboride (TiB2), fabricated using stir casting. The selection of SiC and TiB2 addresses the need for improved hardness, wear resistance, and tensile strength in lightweight materials. Comprehensive mechanical characterization, including tensile strength, hardness, flexural strength, and impact resistance, demonstrated significant improvements. The tensile strength increased from 64.25 MPa to 69.75 MPa, while Vickers hardness rose from 29.9 HV to 69.03 HV, indicating the effectiveness of reinforcement. X-ray diffraction (XRD) confirmed the presence of reinforcing phases, and scanning electron microscopy (SEM) revealed a uniform distribution of particulates, minimizing porosity and enhancing mechanical integrity. Microstructural analysis of fractured surfaces displayed ductile failure characteristics, with micro void coalescence and nucleation sites contributing to the improved mechanical behavior.

Abstract in English:

ABSTRACT The development of low-cost high-entropy alloys is promising to address the demands of expanding industrial applications. In the present research, Co-free FeNiCr medium-entropy alloys were prepared by arc melting and post-processing treatments. The influence of Fe content on the microstructure, mechanical properties and corrosion resistance of these alloys were clarified. The results show that the FeNiCr medium entropy alloys exhibit a single face-centered cubic structure. These alloys consist of a multitude of fine grains and a high density of annealing twining boundary distributed at the interface of the larger grains. The Fe40Ni30Cr30 exhibits both high strength and excellent elongation. The excellent mechanical properties of FeNiCr alloys are mainly attributed to the solid solution strengthening, grain boundary strengthening, twinning induced plasticity (TWIP) effect, dimples toughening, and micropores toughening. The increase in Fe content has been observed to impede the segregation of Cr, dislocation pinning, and the nucleation of grains at the grain boundaries, leading to an increase in elongation and a reduction in strength. In addition, the electrochemical experimental results show that a stable passivation film is formed on the surface of Fe40Ni30Cr30 alloy during the corrosion process, which reduces the corrosion rate and improves the corrosion resistance of the alloy.

Abstract in English:

ABSTRACT Fatigue damage in asphalt pavements is a critical issue affecting the durability and safety of road infrastructure. Traditional fatigue testing methods, such as the indirect tensile fatigue test, fail to replicate the alternating tension-compression stress fields experienced in real-world conditions, leading to inaccuracies in fatigue life predictions. This study investigates the bidirectional splitting fatigue test as an alternative method to better simulate the stress state of asphalt pavements. Using cylindrical AC-13 asphalt specimens subjected to varying stress ratios (0.3, 0.4, 0.5, and 0.6) at 20°C and 10 Hz frequency, the research evaluates vertical displacement trends and fatigue life. Results reveal that bidirectional splitting induces a more realistic stress response, with reduced permanent deformation and slower fatigue progression compared to indirect tensile testing. At lower stress ratios, bidirectional splitting enhances material durability by leveraging compressive stresses for crack healing, whereas higher stress ratios lead to shear failures. These findings underscore the bidirectional splitting test’s potential to improve fatigue performance assessment, paving the way for more resilient asphalt mixtures. The practical implications of these findings lie in their potential application to real-world pavement design and maintenance. Future research should explore its applicability to various asphalt types and real-world loading conditions.

Abstract in English:

ABSTRACT The behaviour of weak clay soil is demonstrated in this article. Nanosilicon dioxide (NSiO2) is added to clay soil in a dry condition to enhance its technical qualities. Different concentrations of NSiO2, such as 0.2, 0.4, 0.6, 0.8, 1.0, and 1.2 percentages, are added. Laboratory tests such as the California bearing ratio test, the proctor compaction test, the compressive strength test, and the Atterbergs limit test are used to determine the cause of the behaviour change. According to these experiments, 1% NSiO2 is the ideal dose needed to improve the soil, and at 0.8% NSiO2 in soil, the ideal moisture level is 20%. For improved performance, the ideal dosage is taken into consideration because exceeding it results in a decline in engineering properties.

Abstract in English:

ABSTRACT Atmospheric Plasma sprayed Alumina-Titania (Al2O3-3wt % TiO2) coatings were deposited onto commercial SS304 substrates. A Taguchi L9 design of experiment protocol was used to optimize the coating process parameters. The effect of three factors: spray distance, the arc current, and scan times on the coating responses was studied. The responses of the plasma sprayed coatings were evaluated in terms of porosity, adhesion Strength, and micro-hardness. The results indicated that porosity levels ranged from 8.8% to 4.8%. Less porosity occurred at higher arc currents and intermediate spray distances. While, adhesion strengths ranged from 9.65 to 11.40 MPa, peaking at higher arc currents and optimal spray distances. In addition, microhardness values ranged from 657.30 HV to 770.20 HV. The relationship between the independent variables and the product responses is fitted using the regression analysis technique. Higher arc current, lower scanning times, and a medium spray distance leading to optimum attributes of low porosity, high adhesion Strength, and high micro-hardness.

Abstract in English:

Abstract Kevlar-reinforced epoxy composites are widely employed in high-performance applications due to their excellent strength-to-weight ratio and impact resistance. However, limitations in wear resistance hinder their use under abrasive conditions. To address this, Alumina (Al2O3) was incorporated as particulate filler at 2%, 4%, and 6% by weight. Composite laminates were fabricated using hand layup followed by compression molding, with a constant Kevlar fiber content of 30 wt%. Mechanical testing was conducted as per ASTM D3039 (tensile), ASTM D790 (flexural), and ASTM D785 (hardness) standards, while wear behavior was evaluated under dry sliding conditions using ASTM G99 with a pin-on-disc setup at 10 N load, 1.5 m/s sliding velocity, and 500 m sliding distance. The addition of 4% alumina yielded optimal performance, resulting in a 28% increase in tensile strength (from 98 MPa to 126 MPa), a 21.6% increase in flexural strength (from 152 MPa to 185 MPa), and a 12.2% increase in hardness (from 82 HRB to 92 HRB) compared to the control. The wear rate was reduced from 3.12 × 10−4 mm3/N·m in the control to 1.89 × 10−4 mm3/N·m at 4% alumina, representing a 39.4% improvement. The coefficient of friction also decreased from 0.52 (control) to 0.46 at 4% alumina.

Abstract in English:

Abstract This study presents a numerical approach to estimate the elastic properties of filler-modified asphalt binders using 2D and 3D micro-mechanical modeling and homogenization principles. A three-phase Representative Volume Element (RVE) model was developed to evaluate the elastic modulus and Poisson’s ratio of glass fiber-reinforced polymer (GFRP) powder filler-modified asphalt binders. Periodic boundary conditions were applied to the RVEs, and linear elastic simulations were conducted for 5wt.%, 10wt.%, and 15wt.% filler contents. The results show that elastic modulus is more sensitive to boundary conditions than Poisson’s ratio. Additionally, elastic modulus increases with mesh density, while Poisson’s ratio remains relatively unaffected by mesh size. The choice of mesh type also significantly impacts the elastic properties. High stress concentrations were identified around the glass fiber particles, suggesting potential failure zones. The estimated elastic modulus values for 5 wt.%, 10 wt.%, and 15 wt.% filler content are 3305.42, 3342.72, and 3380.95 MPa, respectively, with corresponding Poisson’s ratio values of 0.3474, 0.3448, and 0.3421. The Halpin-Tsai model, considered more accurate in the literature, shows good agreement with the FEM results, indicating reasonable accuracy.

Abstract in English:

Abstract This study presents a comprehensive and novel investigation into the environmental sustainability and mechanical behavior of concrete incorporating three classifications of waste tyre rubber—powder, crumb, and chips—as partial replacements for natural aggregates. In contrast to prior research that typically focuses on a single rubber type or limited replacement ranges, this work systematically evaluates the influence of various rubber forms across a full spectrum of inclusion levels, ranging from 0% to 30% in 5% increments. Concrete mixtures were prepared with two distinct water-to-cement (w/c) ratios (0.4 and 0.5) to examine the interaction between mix design parameters and rubber content. Mechanical properties such as compressive strength, ultrasonic pulse velocity (UPV), and dynamic modulus of elasticity were assessed after both 28 and 90 days of curing. Notably, the mix containing 5% rubber at a 0.4 w/c ratio (0.4WR5) achieved a peak compressive strength of 58.81 MPa at 90 days, while the 8% rubber mix exhibited the highest UPV of 5660 m/s challenging the conventional perception that rubber addition invariably degrades concrete performance. These findings demonstrate that optimized rubberized concrete mixes, particularly at 5–10% inclusion levels, can deliver high strength and enhanced durability characteristics, contributing to sustainable construction without compromising structural integrity. Furthermore, the study highlights the critical influence of curing time and w/c ratio on the behavior of rubber-modified concrete, offering valuable design guidance for engineering applications. By effectively utilizing waste tyre rubber, this research contributes to circular economy principles and the reduction of concrete’s environmental footprint, presenting a practical route for diverting rubber waste from landfills.

Abstract in English:

ABSTRACT This study investigates the influence of heat curing on polymer concrete (PC) incorporating high replacement ratios (up to 80%) of recycled aggregates sourced from demolished buildings of different ages to prepare recycle aggregate polymer concrete (RAPC). The research addresses the gap in understanding how recycled aggregate properties, influenced by the age of source structures, impact PC performance under varying curing conditions. Two curing methods were applied: (1) air curing for 28 days and (2) accelerated heat curing at 100°C for 2 hours, followed by air curing. Results show that heat curing significantly enhances compressive strength, reaching 69 MPa in reference specimens compared to 53 MPa under air curing. When using 10-year-old recycled aggregates, RAPC maintained comparable strength (up to 65 MPa at 60% replacement), while 20-year-old recycled aggregates led to lower strengths (51 MPa at 60% replacement). The key contribution of this study lies in demonstrating that heat curing can compensate for strength loss in RAPC, enabling high replacement ratios while maintaining mechanical performance, knowing that the optimal balance between strength retention and sustainability was achieved at 60% replacement. Also, these findings underscore the potential of promoting sustainability by reducing natural resource consumption and construction waste.

Abstract in English:

ABSTRACT Corrosion inhibitors delay the incidence of reinforcement corrosion by decreasing the permeability of concrete. The impact of the commercially available inhibitors on the durability attributes of cover concrete needs more studies, especially the ones exposed to severe environmental conditions. This study mainly aims to investigate commercial inhibitors' efficacy in the bond characteristics of reinforced concrete for three different chloride-induced corrosion exposures. Eighteen specimens with dimensions of 150 mm × 150 mm × 150 mm, with optimum inhibitor dosage, were exposed to one of the three corrosion acceleration methods (induced current, sodium chloride saltwater immersion, and potable water immersion) after normal curing. The bond specimens peak slip, pull-out force, bond strength, and rebar mass loss were assessed after three, five, or seven cycles of wet-dry corrosion exposure. With the rise in immersion cycles, a general decline in bond strength was observed in all specimens. For instance, OW3 exhibited a bond strength of 11.78 N/mm2, which diminished to 9.08 N/mm2 by the time of OW7. In contrast, adding corrosion inhibitors to the concrete mix increased bond strength, measuring 13.06 N/mm2 for OIW3 and 10.03 N/mm2 for OIW7. Using corrosion inhibitors enhanced the bond properties and reduced the mass loss in steel under severe corrosion exposures.

Abstract in English:

ABSTRACT This study investigates the underwater friction stir welding (UFSW) of stir-cast A356 reinforced with 2,4 and 6wt% silicon carbide (SiC) to enhance weld joint performance. A hybrid optimization approach integrating CoCoSO (Combined Compromise Solution) and MEREC (Method based on the Removal Effect of Criteria) was employed to determine the optimal welding parameters. The study optimized welding speed (A), rotational speed (B), axial force (C), and SiC content (D) to maximize tensile strength (TS), elongation (E), and microhardness (HV). The L16 orthogonal array with four factors at four levels was implemented, followed by ANOVA. Optimization results significantly improved welding quality, with CoCoSO identifying ideal parameter combinations, MEREC determining influential parameter weights and RSM optimizing the relationship between process parameters and output responses. The optimal process parameters—welding speed (0.57 mm/s), rotational speed (1300 rpm), axial force (6000 N), and SiC content(8wt%)—enhanced joint efficiency from 63.81% to 97.90%. As a result, tensile strength increased from 191.7 MPa to 222.3 MPa, elongation improved from 2.4% to 7.9%, and yield strength from 117.7 MPa to 261.84 MPa. Microstructural analysis revealed that tensile strength decreased with increasing strain on the advancing side(AS) due to tool deviation ranging from −1.6 to 1.6 mm. These findings validate the effectiveness of optimization in UFSW, demonstrating their potential for achieving superior mechanical properties and defect-free welds in SiC-reinforced aluminum alloys.

Abstract in English:

ABSTRACT This study developed pervious interlocking paving blocks using construction and demolition waste (CDW) and recycled expanded polystyrene (EPS). The reference mix (1:3, w/c ratio of 0.4) used river sand (1.2–2.4 mm) and gravel (4.8–6.3 mm). In the other mixes, the coarse aggregate was replaced by 30% and 100% of CDW and EPS was incorporated at 10% and 20%. Blocks (20 cm × 10 cm × 6 cm) and cylindrical specimens (10 cm × 20 cm) were produced. After wet curing, they were oven-heated at 100°C for 24 hours to reduce EPS volume and create voids. All mixes met the minimum permeability coefficient (10−3 m/s) according to ABNT NBR 16416 (2015). The reference mix and the mix with 30% CDW (with or without EPS) achieved compressive strength near or above the 20 MPa required by ABNT NBR 16416 (2015). However, EPS did not generate voids as expected, likely due to insufficient heating conditions. In conclusion, CDW can replace up to 30% of coarse aggregate, with or without EPS, for pervious block production while meeting ABNT NBR 16416 (2015) standards.

Abstract in English:

ABSTRACT The rational use of materials in construction, particularly cementitious materials, is crucial for environmental preservation. One way to optimize this consumption, especially in mortar production, is to study the packing of fine aggregates and their interactions with the cementitious phase. Several factors influence the rheology of such composites, including void ratio and packing density. This study investigates the role of particle size distribution in packing density by applying classical models and a modified approach. Twenty granular sets were analyzed using these theoretical models, considering different numbers of grain size distribution classes. In this work, packing densities were determined using the CPM (Compressible Packing Model) and a proposed alternative method, while natural sand was used to experimentally validate the theoretical results, reproducing nine of the twenty developed sets. From the analyzed grain size distributions, theoretical models were found to fit natural four-class sands, but their accuracy declined when the number of classes exceeded five classes. The results indicated that increasing the number of grain classes enhances packing density up to 7,5% in natural sands, with this effect being more pronounced in sets derived from theoretical models, ranging up to 13%. The correlation between packing density and the uniformity coefficient followed a sigmoidal fit, suggesting that less uniform sands have higher void ratios. Experimental validation of the theoretical results revealed that the packing density values obtained using the CPM model were 11% to 16% lower than the experimental values. The proposed modified model yielded better results, demonstrating less sensitivity to increases in the fineness modulus.

Abstract in English:

ABSTRACT Multilayerfilms with kesterite are often used for energy conversion, such as photoanode for hydrogen production and manufacture of photovoltaic solar cells. It is due to the fact that they are efficient and use small amounts of material. Cu2ZnSnS4, known as CZTS, is a semiconductor belonging to the kesterite group, which can be obtained in powder or film form. Copper, zinc, tin and sulfide are precursors commonly used in the synthesis of the CZTS. The methodology used to synthesize films is crucial for the success of the final product. It is essential to develop methods which can lower synthesis costs, which can also lower the solar cell costs, for example. Besides the costs, the method must be efficient and increase the efficiency of the devices in which they are employed, and must not be harmful to the environment. This study developed a methodology to synthesize CZTS. It was used in this work dimethyl sulfoxide, copper acetate, tin chloride, zinc chloride and thiourea as precursors. The layers of the film above the glass substrate were characterized with X-ray diffraction, ultraviolet and visible analyses, scanning electron microscopy, fourier transform infrared spectroscopy and X-ray fluorescence spectroscopy. The results absorbance peaks between 300 and 400 nm, in the ultraviolet range, reflectance around 40% in the visible, transmittance reaching above 50% and 50%, and direct band gap about 1.42 ± 0.02 eV associated with the kesterite. The characterization methods proved to be efficient to identify the presence of the kesterite phase at films produced by overlapping layers.

Abstract in English:

Abstract The study examined bus stations in India to identify the potential causes of pedestrian footpath failures and defects in station building components. The factors such as increased pedestrian load, block settlement and environmental degradation significantly impact the long-term durability and performance of paver blocks. This research explores the use of geotextiles to enhance paver block strength and durability, allowing them to withstand heavy traffic while promoting environmental sustainability. Geotextiles, made of high-strength synthetic polymers, offer a sustainable alternative to cement, providing improved durability and eco-friendly benefits. A total of twelve samples with geo-textile ratios ranging from 20% to 60% were tested, yielding impressive mechanical properties including a compressive strength of 36 N/mm² and a flexural strength of 7.1 N/mm². The water absorption and fire resistance capacities exceeded those of conventional paver blocks. The integration of geotextiles also reduces manufacturing costs, construction expenses, environmental impact and resource consumption, offering a sustainable solution for footpath design. Additionally, the study recommends smart materials with applications for station components to enhance the sustainability of station infrastructure. These recommendations address the key issues in bus stations, improving the overall appearance, functionality and service efficiency of the infrastructure, tailored to the Indian context.

Abstract in Portuguese:

RESUMO As argamassas de revestimento são constantemente expostas a variações de temperatura, alternando entre calor e frio, sol e chuva, o que gera ciclos de choque térmico que podem comprometer sua durabilidade. Neste contexto, este estudo avaliou o impacto da incorporação de microcelulose cristalina (MCC) e polpa de nanocelulose fibrilada (NFC) no desempenho e na durabilidade dessas argamassas, com ênfase na resistência aos ciclos de choque térmico. Na metodologia, as argamassas foram avaliadas no estado fresco por meio de ensaios de teor de ar incorporado, densidade de massa e índice de consistência por meio do flow table. Após a cura, foram submetidas a ciclos de molhagem e secagem, simulando o efeito do choque térmico, e avaliadas quanto à resistência à compressão e à tração na flexão. Os resultados indicaram que a polpa de NFC aumentou a incorporação de ar, reduzindo a densidade e melhorando a trabalhabilidade, enquanto a MCC elevou a densidade da mistura no estado fresco. No desempenho mecânico, a polpa de NFC em 0,2% reduziu significativamente a resistência à compressão, enquanto as demais formulações apresentaram comportamento semelhante à referência. As adições de MCC e polpa de NFC empregadas nas argamassas de revestimento não influenciaram positivamente nas propriedades de resistência à tração na flexão. O choque térmico afetou a resistência à compressão, sendo o impacto maior nas argamassas com MCC’s, enquanto as com polpa de NFC’s mostraram maior estabilidade térmica. Já a resistência à tração na flexão os ciclos de choque térmico não foram significativamente influenciados pelas adições testadas.

Abstract in English:

ABSTRACT Rendering mortars are constantly exposed to temperature variations, alternating between heat and cold, sun and rain, which generate thermal shock cycles that can compromise their durability. In this context, this study evaluated the impact of incorporating crystalline microcellulose (MCC) and fibrillated nanocellulose pulp (NFC) on the performance and durability of these mortars, with an emphasis on resistance to thermal shock cycles. In the methodology, the mortars were evaluated in the fresh state through tests for air content, bulk density, and consistency index using the flow table method. After curing, they were subjected to wetting and drying cycles to simulate the effect of thermal shock and assessed for compressive strength and flexural tensile strength. The results indicated that NFC pulp increased air incorporation, reducing density and improving workability, while MCC increased the density of the fresh mixture. In terms of mechanical performance, the addition of 0.2% NFC significantly reduced compressive strength, whereas the other formulations exhibited behavior like reference. The incorporation of MCC and NFC pulp in rendering mortars did not positively influence flexural tensile strength properties. Thermal shock affected compressive strength, with a greater impact on mortars containing MCC, whereas those with NFC pulp demonstrated greater thermal stability. Flexural tensile strength, on the other hand, was not significantly influenced by the tested additions under thermal shock cycles.

Abstract in English:

ABSTRACT Biodiesel research for alternative diesel fuel continues due to the urgent need for sustainable energy solutions. The lower thermal efficiency and increased emissions from biodiesel necessitate further development to improve its practicality. This study examines the effects of TiO₂, Al₂O₃, and ZnO nanoparticles on the performance and emission characteristics of B20 soybean biodiesel in a single-cylinder diesel engine. Experimental tests with biodiesel blends containing 50 ppm and 100 ppm nanoparticles were conducted on an engine while adjusting the load conditions. The results indicated that brake thermal efficiency improved by 5.4%, and brake-specific fuel consumption decreased by 6.7%. The engine's NOx emissions were reduced by 5.7%, and particulate matter and CO emissions decreased by up to 13% and 20%, respectively. The nanoparticle-enhanced reaction resulted in better combustion, which reduced hazardous emissions while producing higher energy output. Research suggests that biodiesel with nanoparticle additives has potential as an environmentally friendly energy solution because it offers improved engine performance with lower environmental impact. Future studies should investigate both the long-term effects on engines and the financial viability of nanoparticle applications to optimize biodiesel technologies.

Abstract in English:

ABSTRACT The global release of carbon dioxide due to human activity raises concerns about the planet's future. These days, the construction sector accounts for a significant portion of emissions; energy use in the sector accounts for roughly 12% of overall emissions, and the cement sector is responsible for 8% of world CO2 emissions. Alternative elements are now used in cement compositions to reduce their negative effects on the environment. Fly ash, a waste product from companies that burn coal, is one substance that is frequently employed. Nonetheless, the overall emissions from the production of concrete may be significantly reduced by a product that is renewable and sinks carbon emissions. Biochar, a byproduct of the pyrolysis of biomass, is one product that could be appropriate for this. In order to assess the performance attributes, concrete containing biochar ratios of 4, 8, and 12 percent based on the cement weight was examined. In order to test this, 100 mm cubes were cast and their compressive strength was measured after 28 and 56 days in the lab. The qualities of workability, density, microstructure, and chemical composition were also assessed. The outcome demonstrated that concrete mixes containing biochar had much less workability. Additionally, the density dropped as the biochar ratio mixture. The similar thing occurred in terms of compressive strength; after 28 days, the sample containing 12 percent had a compressive strength of 48 MPa whereas the comparative species had a compressive strength of 69 MPa. After an additional 28 days of curing, the sample with 12% biochar showed the greatest gain in compressive strength. The samples with and without the addition of biochar did not exhibit any discernible differences in the FTIR.

Abstract in English:

ABSTRACT To address the thermal protection challenges in the combustion chamber of hydrogen-fueled rocket engines, a regenerative cooling channel with conical ribs was proposed and compared with a smooth channel. A numerical study was conducted to investigate the effects of the Reynolds number and rib spacing on both the pressure drop and thermal performance of a cooling channel with conical ribs. The study further explored how these parameters influence the relative heat transfer enhancement capability of the conical ribs, and analyzed the effect of heat flux on the heat transfer characteristics of the conical rib cooling channel. Results show that conical ribs significantly improve thermal performance compared to the smooth channel, with only a marginal pressure drop penalty. Reducing the rib spacing and increasing the Reynolds number maximally decreased the wall temperature of the conical rib channel by 8.15% while improving its thermal-hydraulic performance by 15.60%. The relative heat transfer enhancement capability of the conical ribs diminished as the rib spacing and Reynolds number increased. Increasing the heat flux weakened the thermal performance of the conical rib channel.

Abstract in Portuguese:

RESUMO Os aços avançados de alta resistência (AHSS) têm evoluído nas últimas décadas, consolidando-se como materiais amplamente utilizados na indústria automotiva. Entre os AHSS, destaca-se o aço 22MnB5, que, por meio da estampagem a quente, é moldado em geometrias complexas, alcançando altos valores de resistência mecânica. O resultado é um aço com microestrutura formada por martensita e vestígios de bainita, conferindo elevada capacidade de absorção de energia, ideal para aplicações que exigem alta resistência e durabilidade. O presente trabalho apresenta a caracterização mecânica e microestrutural do aço 22MnB5 estampado a quente e soldado a laser, comparada ao material base. A soldagem propiciou um aumento da resistência à tração, especialmente no limite de escoamento, que apresentou incremento de cerca de 10%, enquanto o limite de resistência à tração aumentou aproximadamente 3%. A dureza da zona fundida e do material base variou em torno de 500 HV, enquanto a zona termicamente afetada apresentou um amolecimento, atingindo cerca de 350 HV. Apesar das mudanças localizadas na microestrutura e da redução de cerca de 50% no alongamento total, comprovou-se a viabilidade da soldagem do aço 22MnB5 com laser de fibra e dois passes opostos.

Abstract in English:

ABSTRACT Advanced high-strength steels (AHSS) have evolved over the past decades, establishing themselves as widely used materials in the automotive industry. Among the AHSS, the 22MnB5 steel stands out, which, through hot stamping, is shaped into complex geometries, achieving high mechanical strength values. The result is a steel with a microstructure formed by martensite and traces of bainite, providing high energy absorption capacity, ideal for applications requiring high strength and durability. This study presents the mechanical and microstructural characterization of hot-stamped and laser-welded 22MnB5 steel, compared to the base material. Welding led to an increase in tensile strength, especially in the yield strength, which showed an increase of approximately 10%, while the ultimate tensile strength increased by about 3%. The hardness of the fusion zone and the base material varied around 500 HV, while the heat-affected zone exhibited softening, reaching approximately 350 HV. Despite localized changes in the microstructure and a reduction of about 50% in total elongation, the feasibility of welding 22MnB5 steel with fiber laser and two opposite passes was demonstrated.

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ABSTRACT Steel-concrete composite structural materials (SCCSM) are extensively used in modern construction due to their high strength, durability, and cost-efficiency. However, accurately predicting their fatigue performance and service life remains challenging, particularly under complex loading conditions. Existing methods for fatigue analysis often fail to address the non-linear mechanical interactions between steel and concrete, leading to imprecise life predictions and inefficient structural designs. To overcome these limitations, this research proposes a comprehensive framework focusing on the mechanical behavior and fatigue performance of SCCSM. The framework integrates advanced modeling techniques, fatigue life prediction models, and experimental validation to account for material heterogeneity and complex loading scenarios. The proposed method utilizes finite element analysis, combined with laboratory testing, to simulate the fatigue behavior of SCCSM under various cyclic loads. It enables accurate identification of critical stress points and material degradation over time. The findings demonstrate that the proposed method significantly enhances the accuracy of fatigue life prediction, improves structural design reliability, and ensures better resource utilization in construction projects. These advancements offer valuable insights for civil engineers and researchers aiming to design safer and longer-lasting composite structures.

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ABSTRACT This study aimed to determine the optimal specimen size using a finite element model, minimizing dimensions for better logistical efficiency while maintaining the stress field’s integrity. The methodology consisted of simulating a cutting process on a specimen, where the only mechanical load applied was the residual stress resulting from the flash butt welding (FBW) process, which is the most commonly used method for joining rail segments. Consequently, any variation observed in the residual stresses was attributed to a redistribution caused by material removal. The cutting process was simulated by sequentially removing elements with the element death feature, replicating vertical cutting conditions. Cutting distances ranged from 200 mm to 25 mm from the weld interface to identify the optimal distance preserving stress field setup. The results showed that stress variation increased as the cut approached the weld interface. A cut at 25 mm caused significant changes in the stress field, with an average difference of 89%, while a 125 mm cut resulted in a smaller 3% variation at measured points. These findings highlight the importance of selecting appropriate specimen sizes to ensure accurate mechanical testing and residual stress analysis in railway applications.

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ABSTRACT This study evaluates the use of coffee husk ash (CHA) as a stabilizer for improving the physical and mechanical properties of low-plasticity clay soils. CHA was incorporated at 4%, 6%, and 8% by weight. Laboratory tests included compaction, unconfined compressive strength (UCS) under dry and saturated conditions, California Bearing Ratio (CBR), resilient modulus, matrix suction, and soil expansion. Results showed significant improvements: CBR increased by 356%, soil expansion was reduced by 24%, and UCS improved by 17.4% (dry) and 28.0% (saturated) compared to natural soil. Higher ash content led to greater water retention and lower matrix suction, enhancing internal cohesion and stiffness under varying moisture. The resilient modulus also increased with curing time and ash content, reaching up to 25% after 28 days. These findings demonstrate that CHA can significantly enhance both mechanical and hydromechanical behavior of clay soils, making it a suitable alternative for road and infrastructure applications. One challenge addressed in this study is the lack of standardization in the use of agricultural ashes for soil stabilization. Since coffee husk ash is often discarded or underutilized, its application in geotechnical contexts may offer a promising alternative to reduce waste and promote the use of locally available materials.

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ABSTRACT The VP50 steel, characterized by its bainitic/martensitic microstructure, poses significant machining challenges, including elevated cutting forces and heat generation. These factors directly impact surface roughness, as hardened surfaces tend to exhibit greater irregularities when cutting parameters or tools are not properly optimized. The objective of this study is to critically analyze the quality of machined surfaces using CAD/CAM programming tools during the milling of VP50 steel cavities with spherical-tip carbide inserts. The analysis focuses on the influence of two types of interpolations (linear and circular) and tolerances (0.05 mm and 0.1 mm), which define the tool path during the machining of a three-dimensional cavity. Surface roughness and geometric accuracy were selected as the primary responses due to their crucial role in determining the functional performance and quality of machined components. These indicators are widely used in the literature as key metrics for evaluating the efficiency of machining strategies and the impact of CAD/CAM parameters on the final product quality. The results indicate that circular interpolation with a 0.1 mm tolerance is the most effective option for minimizing shape deviations and enhancing process accuracy.

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ABSTRACT Friction Stir Welding (FSW) is an effective solid-state joining technique for dissimilar aluminum alloys, offering superior mechanical properties compared to conventional fusion welding methods. This study investigates the optimization of FSW process parameters for joining AA 6061-T651 and AA 7075-T651 with magnesium (Mg) and chromium (Cr) as reinforcements. The influence of tool rotational speed, welding traverse speed, and Mg-Cr mixing ratio on weld quality was examined through microstructural and mechanical characterization. The optimal welding parameters-1400 rpm rotational speed, 60 mm/min traverse speed, and a 95:5 Mg-Cr reinforcement ratio, yielded a significant enhancement in mechanical properties. The tensile strength increased from 139.33 MPa in conventional FSW to 249.09 MPa in reinforced joints, while hardness improved from 107.54 HV to 185.68 HV, reflecting a respective increase of 78.78% and 72.66%. Additionally, coolant with different mixing ratios was utilized in this investigation to analyze its effect on weld quality. Scanning Electron Microscopy (SEM) analysis verified defect-free weld zones with Cr preventing crack formation and Mg2Si particles remaining stable. Magnesium content increased from 1 weight % to 2.1 weight % according to Energy Dispersive Spectroscopy (EDS) analysis and there were also traces of Cr (0.2 weights%) in the nugget zone. The mechanical performance and weld integrity of dissimilar aluminum alloy joints are enhanced by the addition of magnesium and chrome reinforcements as demonstrated by these results. This welding technique is appropriate for high-performance applications in the automotive marine and aerospace industries where lightweight and high-strength materials are crucial due to its improved strength and flawless microstructure.

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ABSTRACT This study explores the effects of metakaolin (MK), fly ash (FA), superplasticizer, and banana and basalt fibers on concrete’s mechanical properties through a comprehensive experimental analysis. The materials employed include ordinary Portland cement (OPC) 53 grade, M-sand, coarse aggregates, 12.5% MK and FA, and superplasticizer (Sika at 0.5%), blended with banana and basalt fibers in varying proportions of 0%, 0.5%, 1%, and 1.5%. A total of 13 beam specimens, each measuring 1000 mm × 100 mm × 150 mm, were cast, including a control specimen. The primary focus of the study is to evaluate the mechanical behavior of the concrete beams under single-point load testing. Key parameters such as deflection, ductility, stiffness, energy absorption, and energy dissipation were examined. Among the various mixes, the combination with 1.5% basalt fiber and 12.5% MK (BSFM3) exhibited superior performance in terms of strength, stiffness, and overall mechanical properties. The study conducts a detailed microstructural analysis to understand the concrete mixes and performance. Comparative analysis with experimental results and existing literature underscored the enhanced performance of this mix and analyse the microstructural properties. These findings provide valuable insights for optimizing concrete mix designs, enabling engineers, architects, and construction professionals to create durable, sustainable structures.

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Abstract This study investigates the influence of milling parameters on the surface integrity and corrosion behavior of austenitic 304 stainless steel (SS). The experiments were designed using a Taguchi L16 orthogonal array to evaluate the effects of feed rate and cutting speed on surface characteristics. Commercial-grade 304 SS was subjected to milling under varied conditions, followed by microstructural characterization and electrochemical corrosion testing. Surface integrity was assessed through surface roughness (Ra, Rz, Rt, etc.) and Vickers microhardness (HV200), while corrosion behavior was evaluated via potentiodynamic polarization in a 0.1 mol/L NaCl solution using a three-electrode setup. The results revealed that lower feed rates and moderate cutting speeds tended to produce smoother surfaces and increased microhardness due to work hardening, which contributed to enhanced pitting resistance. A polished specimen was included for comparison and showed the lowest surface roughness and microhardness values. However, the corrosion potential and pitting resistance of the polished specimen were not significantly better than those of the milled specimens under optimal parameters. This suggests that surface roughness alone does not dictate corrosion behavior; rather, a combination of topographical and microstructural factors, such as the presence of a work-hardened layer and nanocrystalline grain structure, plays a critical role. The study demonstrates the complex interaction between milling conditions, surface integrity, and corrosion performance, offering valuable insight for selecting machining parameters that optimize both surface quality and corrosion resistance in industrial applications.

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ABSTRACT The use of industrial co-products as components for civil construction has been a good way to promote a circular economy in the sector. However, this material must be analyzed so it avoids offering future risks. Life cycle assessment is an essential tool to quantify the environmental impact of replacing or integrating new components. Thus, this study aims to compare the potential environmental impacts between a crushed embankment designed with crushed natural aggregate (gravel and clay) and an embankment designed with steel aggregate to replace gravel on the OpenLCA software, which is an open life cycle assessment tool. The carried-out assessment considered the impact of materials and the construction of the embankment (cradle to construction site). Results indicate that using steel aggregates to replace natural aggregates offers environmental advantages for the evaluated proposition as the steel plant lies within up to 243 km from the work site.

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ABSTRACT This research evaluates the performance of concrete mixtures incorporating fly ash, Ordinary Portland Cement (OPC), and varying proportions of recycled coarse aggregate (RCA) along with natural coarse aggregate (NCA). The study including slump, compressive strength, split tensile strength, flexural strength, sulfate resistance, and water absorption, to determine both the mechanical properties and the durability of the concrete mixes. The slump test revealed a reduction in workability with increasing RCA content, while the compaction factor indicated improved compactness in these mixes. Compressive, tensile, and flexural strength tests showed enhanced strength characteristics for mixes with up to 20% RCA, outperforming conventional concrete at 28 days. Sulfate resistance tests indicated that increasing RCA content reduced durability, while flyash improved resistance in certain mixes. Water absorption tests demonstrated con-sistent increase in absorption with higher RCA proportions, highlighting the difference between sustaina-bility and durability. The results were analyzed using ANOVA, confirming statistically significant variations in performance across different mixes. The study concludes incorporating RCA with flyash can improve strength properties while slightly compromising durability. This work underscores the potential of recycled aggregates in sustainable concrete production and provides a framework for optimizing concrete mixes balance environmental benefits with mechanical and durability performance.

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ABSTRACT Stainless steels are pivotal materials in industry and find extensive application in various types of equipment due to their excellent chemical properties, such as high corrosion resistance and the ability to withstand elevated temperatures. However, they exhibit greater machining challenges compared to common carbon and low-alloy steels, mainly because of their high work-hardening rate during cutting operations. Consequently, the industry has a strong interest in understanding and monitoring machining techniques for these materials. This study introduces a novel approach by correlating tool wear progression with chip morphology in the dry turning of SAE 304 stainless steel, using coated carbide tools. Wear tests were carried out, and chip samples were collected at each stage of tool wear. Analyses of chip type and shape were performed, followed by metallographic evaluations. The results indicate a measurable correlation between wear stages and chip morphology, suggesting that chip analysis can serve as a practical method for real-time tool condition monitoring.This finding provides a cost-effective alternative for tool wear assessment, enhancing the efficiency and reliability of machining operations involving austenitic stainless steels.

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ABSTRACT This research investigates the performance enhancement of cement slurry composites for well-sealing applications through the incorporation of CNTs and NS. Experimental results revealed that the optimized hybrid composite (M3), containing 0.5% CNTs and 1% NS, achieved a compressive strength of 63.5 MPa at 7 days, a 64.39% improvement over the control sample (B, 38.6 MPa). Flexural strength increased by 62.95%, reaching 8.8 MPa. Triaxial testing demonstrated a peak strength of 71.6 MPa under a confining pressure of 10 MPa, highlighting the composite's superior mechanical stability. Microstructural analysis confirmed that CNTs bridged microcracks, while NS filled voids, reducing the average pore size from 120 nm (B) to 45 nm (M3) and total porosity from 18.5% to 9.8%. XRD analysis showed an 85% reduction in CH content, with significant C-S-H formation contributing to improved durability. Stability tests indicated negligible free water (<0.1%) and a density difference of 0.01 g/cm3, confirming excellent homogeneity. These findings demonstrate that the synergistic use of CNTs and NS significantly enhances the mechanical, microstructural, and durability properties of cementitious materials, providing a promising solution for high-performance well-sealing applications.

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Abstract Ambient cured geopolymer concrete offers a sustainable and durable alternative to traditional Ordinary Portland Cement (OPC) based concrete. Recent advancements in materials, mix de-sign, and activators have made it feasible for use in a wide range of applications, from pavements to precast elements. The study investigates the possibility of developing a sustainable ambient cured geopolymer concrete through the utilization of fly ash and Ground Granulated Blast Furnace Slag (GGBS) as precursors. The overall objective of the current study is to promote sustainability in the development of concrete mixes without compromising the strength. In total, different trails were prepared by fly ash with GGBS upto 30% in levels of 10%. The fresh properties such as workability in terms of slump, setting time and consistency and mechanical strength properties, including compressive strength, split tensile strength, and flexural strength, were evaluated at 7 and 28 days. The determined properties are compared with the conventional concrete mix. Further, slabs were casted to determine the static vertical load carrying ca-pacity. The results indicate that a geopolymer concrete mix with 80% fly ash and 20% GGBS de-livers optimal strength performance. This 80:20 proportion exhibits significantly higher load-carrying capacity compared to the 90:10 and 70:30 mixes, as well as conventional concrete. The load-carrying capacity of the 80:20 mix shows an improvement of 28.15% over conventional con-crete.

Abstract in Portuguese:

RESUMO A caracterização mecânica e microestrutural de produtos estampados é essencial para a identificação de defeitos e orientar a melhoria das propriedades, ampliando a gama de aplicações para diferentes tipos de materiais. Nesse contexto, o estudo da relação entre as propriedades mecânicas e o respectivo arranjo microestrutural assumidos por um material após uma operação de estampagem é um método útil para o controle de qualidade, assim como para avaliar a ocorrência de falhas como o desenvolvimento de uma orientação cristalográfica inadequada e a identificação de regiões que sofreram um estado de tensões e deformação plástica que podem ocasionar problemas como o afinamento da espessura da chapa. Este trabalho executa a caracterização mecânica de um copo estampado com uso do aço inoxidável ferrítico AISI 444 por meio da operação de embutimento com a descrição do perfil de dureza Vickers em diferentes posições, combinada com a apresentação do respectivo aspecto microestrutural nessas mesmas posições da caracterização mecânica. Considerando que a operação de estampagem foi realizada a frio, a análise microestrutural indicou reduzida orientação dos grãos, mesmo nas regiões que sofreram maior quantidade de deformação plástica e encruamento, e consequentemente, maior dureza Vickers. Observou-se ainda que a variabilidade da dureza em função doo posição do copo estampado foi maior que a detectada para o aspecto microestrutural.

Abstract in English:

ABSTRACT The mechanical and microstructural characterization of stamped products is essential to identify defects and be a guide to improve the properties in general, amplifying the range of applications for different types of materials. In this context, the study of the relationship between the mechanical properties and the respective structural arrangement assumed by steel during a stamping operation is a valuable method for control of quality, as well as for assessing the occurrence of failures such as the development of an inadequate crystallographic orientation for a stamped product and the identification of regions that experienced intense mechanical efforts and plastic deformation, considered critical to a possible sheet thinning. This work executes the mechanical evaluation of AISI 444 ferritic stainless cup, with the description of Vickers hardness profile in different positions, combined with the corresponding microstructural aspects in the same positions of the mechanical investigation. Considering that all experimental procedures were conducted under cold working, the microstructural analysis exhibited reduced grain orientation, even in the regions that experienced a higher amount of plastic deformation and work-hardening and, consequently, higher Vickers hardness. It detected a higher variability of mechanical resistance than modifications in the microstructural aspects of AISI 444 ferritic stainless steel.

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Abstract This study reports a facile synthesis of Au-modified Nano-SnS2 composites through a combined water-thermal and in situ chemical reduction method, aimed at advancing low-temperature gas sensing technology. Comprehensive structural analyses using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy confirmed that incorporation of Au nanoparticles significantly alters the nanostructure. The results reveal that optimal Au loading at 0.5 wt% refines the crystallite size from approximately 25 nm to 20–23 nm, while uniformly distributed Au particles with diameters of 3–5 nm effectively form Schottky junctions that enhance interfacial charge transfer. Gas sensing measurements demonstrate that the sensor response increases from 4.7 at 1 ppm to 22.6 at 10 ppm NO2, and a linear correlation (R2 = 0.998) was observed in the lower concentration range of 1–4 ppm. Furthermore, the optimal operating temperature decreased from 140°C for the unmodified sensor to 120°C, contributing to reduced power consumption. The transient response characteristics also improved markedly, with a response time of 42 s and a recovery time of 127 s, in contrast to 220 s and 520 s for the pristine material. Long-term stability tests over 40 days revealed less than 4% variation in sensor performance, and selectivity experiments confirmed a strong preference for NO2 over other interfering gases. Overall, the synergistic effects of Au-induced electronic sensitization and catalytic activity result in enhanced sensitivity, faster kinetics, and excellent durability. These significant findings offer valuable insights for designing highly efficient sensors for environmental monitoring, paving the way for future sensor technology.

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ABSTRACT The temperature characteristics and workability of Recycled Hot Mix Asphalt (RHMA) are critical determinants of pavement construction quality. This study investigates these factors by conducting an orthogonal mixing experiment, considering four variables-aggregate gradation, asphalt content, mixing time, and preheating temperature of reclaimed asphalt pavement (RAP) – each at four levels, with RAP contents of 30%, 40%, and 50%. An infrared thermal imager is employed to measure the temperature, and the workability evaluation index is calculated based on the motor’s output power. The analysis revealed that higher RAP content adversely impacts both heating efficiency and workability. RAP preheating temperature emerged as a dominant factor, significantly affecting temperature uniformity and the final mixing temperature. Insufficient RAP preheating can be mitigated by overheating new aggregate to compensate for the temperature deficit. The relative influence of factors on low-temperature regions follows the order: RAP preheating temperature > mixing time > asphalt content > gradation index. With increasing RAP content, the influence of RAP preheating temperature on RHMA workability becomes more pronounced, while the remaining factors influence workability in the order: mixing time > gradation index > asphalt content. This study offers valuable insights into the temperature and workability dynamics of RHMA during the hot-mix process, providing a theoretical basis for optimizing mixing parameters and improving construction quality.

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ABSTRACT In-fill aluminum bar is a lightweight product with high energy absorption, weight ratio, and mechanical, chemical, and physical qualities. Al6061 bar in-filled with Stainless Steel Structure (SSS) is mould cast to test its flexural response. The experimental investigation has two stages: the first predicts the binding ability between the Stainless Steel (rod & wire) core and aluminium, and the second estimates flexural, pull-out, and compression properties to ensure fit. Pull-out and SEM tests evaluate SS304 rod and wire reinforced with AL6061 matrix binding. Secondary evaluations of SSS-filled composites use several material characterisation methods. MIG is used to wire and rod-form SS304 in-fill structures. The mechanical properties of wired and rod-in-fill SSS with aluminum bar have been experimentally examined. After heat treatment, the rectangular bar’s energy absorption and flexural strength improved. SEM examination is used for micro and macroscopic analyses to show the in-fill structure’s role in the aluminum matrix. Higher flexural strength of about 1559.5 MPa is attained after heat treatment process for perforated small hole specimen with energy absorption rate of 988.5 J on comparing other specimens. Finally, in-fill structure with aluminum bar outperforms higher than raw Al6061 alloy.

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ABSTRACT This study aims to analyze and compare two methods for measuring the thermal conductivity of EVA sheets obtained from reprocessed industrial scraps. The experiments were conducted using a cylindrical wall method and a flat plate propagation method to evaluate their cost-effectiveness, accuracy, and compliance with current standards. Results indicate that the cylindrical wall method is more cost-efficient (($0.042) compared to the flat plate method (($1.25). However, the flat plate method better simulates real conditions by providing the necessary time for thermal equilibrium. The lowest thermal conductivity was observed in the thin blanket (TNB) configuration (0.66 W/m°C), whereas the highest conductivity was noted in the configuration with two thick blankets (2TKB) (42.4 W/m°C). Both methods showed consistency with existing standards, with further calibration required using standard insulation materials. These findings suggest that the tested Ethylene Vinyl Acetate sheets (EVA) sheets are viable thermal insulators with satisfactory attenuation properties.

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ABSTRACT Self-Compacting Concrete (SCC) is a special type of concrete which does not require external mechanical compaction and it compacts by its own self weight. Due to its high flow ability and high resistance property, it is being used in congested reinforcement areas and high rise structures. Inclusion of fiber in SCC is an effective solution to manage the heavy load conditions. SCC with fiber addition results in enhancing tensile and flexural strength properties. This present research aims to predict the strength behaviour of SCC using hybrid fibers. Furthermore, the automatic validation is achieved by Optimal Recurrent Neural Network (ORNN) technique which has been developed to analyze the compressive strength, tensile strength and flexural strength. The ORNN is a combination of Recurrent Neural Network (RNN) and Dingo Optimizer (DO). Moreover, in the aspect of durability behaviour SCC with hybrid fiber concrete is made and heated at a temperature of 210°C, 320°C, 530°C and 790°C after their curing period as per ISO 834 guidelines. Test results proved that when the concrete is subjected to high temperature, there was decrease in compressive strength properties. Moreover, the present research findings are implemented in MATLAB for computing the strength properties and the results are discussed elaborately. In order to validate the proposed method, 80% of data is used for training and remaining 20% of data is utilized for testing. This research study is highly valuable towards Civil and Structural Engineering, particularly in the design and analysis of fire-resistant infrastructure, high-performance concrete elements, and intelligent construction materials.

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ABSTRACT This study explores the potential of nano-graphene particles for the sustainable manufacturing of concrete. The primary goal is to predict the compressive strength of graphene-incorporated concrete by evaluating the effects of materials such as cement, graphene, fly ash, water usage, aggregate levels, curing ages, and superplasticizer dosages. A total of 350 data entries were sourced from various literature. Multiple machine learning techniques, such as Adaptive Boosting, Decision Tree, Gradient Boosting, k-nearest Neighbors, Light Gradient Boosting, and XGBoost, were utilized to study how these variables influence compressive strength. The dataset was split into an 80%–20% train and test set for developing the prediction algorithms. Among the models, the XGBoost model delivered the highest precision, with a coefficient of determination of 0.921 in the training stage. To ascertain how the input parameters affected the outcome, SHAP and partial dependence plots were employed for each variable's contribution to the improvement of strength. Based on the parametric optimization, incorporating graphene at a range of 0–2 kg/m3 in the concrete mix led to the maximum increase in compressive strength. This work enhances machine learning-based nano-engineered concrete production by removing experimental methods, reducing labor and resource demands, minimizing environmental footprint, and providing graphene-modified concrete design data.

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ABSTRACT The pavement maintenance field produces a large amount of waste materials, primarily composed of reclaimed asphalt pavement (RAP) and recycled concrete aggregate (RCA), and considering the shortage of natural materials in pavement engineering, the production of sustainable asphalt mixtures to reduce the demand for natural materials become a topical issue. To this end, this study aims to assess the feasibility of utilizing RAP and RCA for the production of sustainable asphalt mixtures. Seven schemes of asphalt mixtures were designed, containing varying proportions of RAP at 20% and 30%, and RCA at 15%, 25%, and 35%, as well as a control scheme with natural materials. A battery of tests, such as Marshall stability, rutting, freeze-thaw splitting, low-temperature bending, and fatigue cracking performance tests, were conducted to evaluate the optimum asphalt content (OAC) and the durability properties of sustainable asphalt mixtures. In addition, the significance of the effect of RAP and RCA was analyzed using the ANOVA method, and the economic benefits of sustainable asphalt mixtures were analyzed. The results show that the OAC of sustainable asphalt mixtures escalates with higher proportions of RAP and RCA. The high-temperature stability, moisture stability, and fatigue performance of sustainable asphalt mixtures can be improved by adding RAP and RCA, albeit with a slight reduction in low-temperature cracking resistance. RCA emerges as a significant factor influencing the mechanical properties of sustainable asphalt mixtures, while RAP primarily impacts low-temperature cracking resistance. The utilization of RAP and RCA yields cost reductions in asphalt mixture production, leading to substantial economic benefits.

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ABSTRACT Generation of waste from the consumption of human society at the global level is an increment level day by day. The daily life requirements of the human society start from water consumption, clothes, vehicles for travel, power consumption, drugs etc. The utilization of these facilities by the public leads to different pollution and also generation of waste in different forms. The disposal of the generated waste poses a threat to the human society which needs more attention in the present scenario. Also, utilization of waste results in a sustainability by reducing their environmental footprints and conserving resources. In this article, the sludge generated from the textile industry effluents after its treatment and hypo sludge a waste generated from paper industry were taken for the experimental study. The physico chemical characteristics were analyzed and an attempt was made to utilize the sludge to replace cement in the manufacturing of hollow concrete blocks. The hollow concrete blocks were cast and tested as per the recommendations of BIS standards. The experimental study reveals that about 10% of cement can be replaced effectively for the manufacturing of hollow concrete blocks and possible standards are achieved.

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VISUAL ABSTRACT

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ABSTRACT This study investigated the effects of reinforcement ratio and fatigue load level on the fatigue performance and residual capacity of ultra-high performance concrete (UHPC) continuous box beams in the negative moment region. Six UHPC specimens were designed and fabricated, with some tested statically and others subjected to fatigue loading. The research specifically examined how reinforcement ratio and fatigue loading influence structural performance parameters, including mid-span deflection and reinforcement strain, during fatigue testing. And the accuracy of the experimental results was further verified through finite element numerical simulations. The experimental results demonstrated that: During static loading tests, beams B1 and B2 demonstrated an increase in flexural capacity of 8% and 25%, respectively, relative to the reference beam B0. These findings indicate that the application of UHPC in the negative moment region of simply supported-to-continuous box beams significantly enhances flexural performance. This enhancement is attributed to optimized stress distribution within the cross-section, which improves ductility and damage tolerance. Following 2 million fatigue cycles, no observable fatigue damage was detected in beams PLB0, PLB1, or PLB2. Post-fatigue static failure tests were subsequently conducted on these beams. Compared to their corresponding reference beams (B0, B1, B2), PLB0, PLB1, and PLB2 exhibited reductions in maximum mid-span deflection of 30%, 16.1%, and 5.8%, respectively, along with markedly lower reinforcement stress amplitudes. Beam PLB0 exhibited a 10% reduction in residual capacity relative to the static ultimate capacity of reference beam B0. Conversely, beams PLB1 and PLB2 demonstrated residual capacity increases of 4% and 21%, respectively, surpassing the static ultimate capacity of their corresponding reference beams (B1 and B2). These findings demonstrate that UHPC implementation enhances flexural stiffness, retards fatigue damage accumulation, and effectively increases residual capacity in bridge components.

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Abstract The performance of concrete that contains different amounts of fly ash, silica fume, and ground granulated blast furnace slag (GGBS) as partial cement replacements is examined in this study. Workability, water absorption, weight loss, strength loss, compressive strength, split tensile strength, flexural strength, and chloride ion permeability were assessed for 17 mix formulations at 7, 14, 28, 56, and 90 days. The Rapid Chloride Permeability Test (RCPT) was used to evaluate durability, while scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to analyze the microstructure and phase composition, respectively. With a compressive strength of 85.69 MPa at 28 days, split tensile strength of 5.82 MPa, flexural strength of 9.64 MPa, and water absorption of 1.21% after 90 days, the ideal mixture of 7.5% fly ash, 7.5% silica fume, and 7.5% GGBS demonstrated the optimum performance. Losses in weight and strength were negligible, at 0.85% and 2.37%, respectively. There was little chloride permeability (815 Coulombs). A dense microstructure was seen by SEM, and further C-S-H development was verified by XRD. A score of −2.45% from the Percent Bias (PBIAS) study indicated that the model prediction was accurate. All things considered, blended cementitious ingredients improve mechanical and durability qual-ities while encouraging environmentally friendly concrete production by using less cement.

Abstract in English:

ABSTRACT Carbon nanomaterials have revolutionized wearable technology by enabling the development of lightweight, flexible, and highly sensitive devices for real-time monitoring of athletes and performance tracking. These devices provide valuable insights into athletes’ physiological and biomechanical parameters, aiding in the optimization of performance and the prevention of injuries. However, existing wearable systems often suffer from limited sensitivity, data inaccuracies, and a lack of personalized feedback, which hinder their effectiveness in supporting elite athletic performance. This study proposes an Artificial Intelligence-Driven Personalized Athlete Monitoring System (AI-PAMS) to monitor and track the performance of athletes. The system integrates carbon nanomaterial-based sensors with advanced AI algorithms to ensure accurate data collection, real-time analysis, and actionable insights tailored to individual athletes. AI-PAMS incorporates noise reduction for sensor data, machine learning for predictive analysis, and adaptive feedback systems for personalized recommendations. The proposed method enhances usability in professional sports training by providing real-time dashboards, automated alerts, and adaptive training insights to improve athlete performance and reduce the risk of injuries. Findings demonstrate that AI-PAMS achieves higher accuracy, improved data reliability, and superior adaptability compared to traditional methods, making it an ideal solution for next-generation sports monitoring. The system is tested on a group of athletes under varied conditions, and performance is evaluated across metrics such as accuracy (97.23%), data reliability (95.83%), and adaptability (94.67%).

Abstract in English:

This study aims to deepen the understanding of the formation of tricalcium silicate (alite) polymorphs in synthetic clinker, produced under controlled conditions that simulate industrial scenarios, with the goal of contributing to more sustainable practices in Portland cement production. The innovation of this research lies in the combined evaluation of the effects of crystallinity and particle size of silica—in the forms of crystalline quartz and amorphous silica gel, across different granulometric ranges—on the nucleation and stabilization of the M1 and M3 monoclinic polymorphs of alite. Using advanced characterization techniques such as laser granulometry, X-ray fluorescence, X-ray diffraction, and optical microscopy, it was demonstrated that increasing the silica particle size, regardless of crystallinity, reduces the alite content and promotes an increase in the content of free lime and belite. Furthermore, the silica particle size directly influences the size of alite crystals, while the interaction between crystallinity and particle size has a significant impact on the stabilization of alite polymorphs. These findings are essential for optimizing the clinker manufacturing process, potentially reducing energy consumption and promoting the production of more reactive forms of cement, thereby contributing to sustainability in the cement industry.

Abstract in English:

ABSTRACT Currently, the concrete structure is being developed using alternative materials, and the strength properties of the concrete have improved in various aspects. The coarse particles are removed from the concrete and the fine particles in the concrete. It tends to improve the mechanical and durability properties of the concrete in different environmental conditions. This research examined the mechanical and durability properties of the Reactive Powder Concrete (RPC) under environmental conditions. This study’s primary objectives were to evaluate the RPC’s compressive, split tensile and flexural strength. Additionally, the durability properties of the RPC were examined in various immersion conditions. The RPC is investigated by incorporating the glass fibre in various percentages of 0.1%, 0.2%, 0.3% and 0.4%, respectively. The optimum glass fibre 0.75% enhanced the mechanical properties of the RPC by 15%, 24% and 27% for compressive, split tensile and flexural strength compared to the conventional RPC mix. The durability properties of the RPC were improved by 23% compared to the conventional RPC mix subjected to acid resistance. Furthermore, microstructural analyses such as SEM and EDAX were evaluated for both the conventional and optimum mixes of RPC. These analyses help to examine the morphology and chemical components of RPC. Linear regression analysis was performed in this study to predict the mechanical properties of RPC. The relationships between compressive and split tensile strength, as well as compressive and flexural strength, showed a high correlation with the experimental results. The linear regression coefficient (R2) is 0.96 for compressive and split tensile strength and 0.97 for compressive and flexural strength. This research can be recommended for practical applications in developing sustainable structures.

Abstract in English:

ABSTRACT This study developed and systematically investigated a novel protective coating system combining graphene oxide (GO) and Ti3C2Tx for enhanced steel surface protection. Through careful optimization of synthesis parameters and composition ratios, we achieved uniform dispersion and strong interfacial interactions between the components, resulting in a dense, well-adhered coating structure. The composite exhibited exceptional mechanical properties, with nanoindentation measurements revealing uniform distribution of hardness (coefficient of variation <8%) across the coating surface. Electrochemical analysis demonstrated the coating’s remarkable barrier properties, with impedance measurements showing charge transfer resistance values exceeding 109 Ω·cm2 in 3.5 wt% NaCl solution. The coating maintained structural integrity and protective performance during prolonged environmental exposure, retaining over 85% of its initial adhesion strength after 30 days under accelerated aging conditions. Potentiodynamic polarization studies revealed a significant reduction in corrosion rate, with the corrosion current density decreasing by three orders of magnitude compared to unprotected steel. The optimized coating system demonstrated excellent long-term stability in salt spray testing, maintaining a high corrosion rating throughout 1000 hours of exposure, indicating its potential for practical industrial applications.

Abstract in English:

ABSTRACT This study seeks to assess the impact of the fine-to-coarse aggregate ratio (FA/CA) on the early-age mechanical properties of polyurethane concrete (PUC) designed for quick repair applications. Three sample FA/CA ratios (0.42, 0.54, 1.00) were established based on an optimized particle packing model. The critical characteristics, including compressive and flexural strength, were evaluated after 24 hours. Each test group had at least five specimens, and the results were statistically evaluated using one-way ANOVA and Tukey’s post hoc test (p < 0.05) to verify data reliability. The findings demonstrate that an FA/CA ratio of 0.54 produces enhanced overall strength performance (compressive: 74 MPa; flexural: 8.5 MPa), due to optimized particle dispersion and minimized voids. The FA/CA ratio of 1.00 enhances workability but markedly diminishes mechanical strength. Although this study lacks in-depth discussions of microstructure, long-term durability evaluation, and some transport-related characteristics, the results confirm the potential of PUC. Preliminary results show that PUC is a viable alternative to conventional repair mortars, not only for pavement overlays but also for bridge decks, expansion joints, and other concrete surfaces that require rapid rehabilitation.

Abstract in Portuguese:

RESUMO Este estudo investigou a resistência (fvt) e a rigidez (Gvt) ao cisalhamento transversal (rolling shear) de elementos de madeira lamelada colada cruzada (MLCC) produzidos com madeira nativa brasileira de Marupá (Simarouba amara). Para isso, foram adotadas abordagens numérica e experimental, além do desenvolvimento de uma equação analítica para avaliar a rigidez (Gvt) das camadas transversais de painéis com três camadas de mesma espessura por meio de ensaios de flexão. Durante a etapa experimental, foram feitos ensaios de cisalhamento em dois modelos de corpos de prova (vertical e inclinado), além de ensaios de flexão em vigas e em painéis. A modelagem numérica baseou-se no método dos elementos finitos, utilizando-se o software ABAQUS para a avaliação das amostras. Os valores do Gvt foram de duas a seis vezes superiores aos valores de referência, enquanto a resistência (fvt) foi de duas a três vezes superior. A equação analítica desenvolvida mostrou-se adequada para a determinação da rigidez ao rolling shear (Gvt) por meio de ensaios de flexão. A modelagem numérica indicou que as falhas ocorreram predominantemente na camada central das amostras de MLCC, em razão da concentração de tensões de cisalhamento, com contribuição de tensões normais de compressão (nos ensaios de cisalhamento) e de tração (nos ensaios de flexão). O método de ensaio com corpo de prova inclinado demonstrou ser o mais apropriado para determinar as propriedades relacionadas ao cisalhamento transversal (rolling shear).

Abstract in English:

ABSTRACT This study investigated the rolling shear strength (frs) and stiffness (Grs) of cross-laminated timber (CLT) elements produced with Brazilian native Marupá wood (Simarouba amara). Therefore, numerical and experimental approaches were used, and an analytical equation was developed for three-layer panels of equal thickness for the determination of the shear stiffness (Grs) of the transverse layers of three-layer panels with equal thickness through bending tests. During the experimental phase, shear tests were conducted on two specimen models (vertical and inclined), and bending tests were performed on beams and panels. The numerical modelling was based on the finite element method, and the ABAQUS software was used to evaluate the tested samples. The rolling shear stiffness (Grs) was two to six times higher, while the strength (frs) was two to three times. The developed analytical equation was suitable for determining the rolling shear stiffness (Grs) through bending tests. The numerical modeling revealed that the failure primarily occurred in the central layer of the CLT samples due to the shear stresses concentration, with contributions from normal compression (for shear) and tensile stresses (for bending). The inclined shear test method was the most appropriate for determining the rolling shear properties.

Abstract in English:

ABSTRACT This study investigates the combined effect of reactive Magnesium Oxide (MgO) and Recycled Aggregates (RA) on the shrinkage and mechanical behavior of High-Performance Concrete (HPC), with a focus on sustainable and eco-concrete development. Unlike previous studies that typically examined MgO or RA in isolation, this work uniquely explores their interaction across varying RA levels (0%, 25%, 100%) and two curing periods (7 days and 6 months). Ten concrete mixes were prepared, with 10% Ordinary Portland Cement (OPC) replaced by MgO in half of them. The findings reveal that MgO reduced autogenous shrinkage by up to 93% due to Mg(OH)2 formation, while overall shrinkage was lowered by 22–39% depending on RA content. However, MgO also increased drying shrinkage due to greater water demand, especially at higher RA levels. A key novelty is the identification of threshold RA contents—35% at early age and 42% at maturity—beyond which the shrinkage contribution from RA offset MgO’s benefits. Mechanically, MgO caused a modest 5–8% reduction in strength properties. However, at 100% RA, the combination with MgO led to up to 21% strength loss, attributed to poor aggregate–matrix interaction. This study provides new insights into the synergistic and competing effects of MgO and RA in HPC, helping define optimal material combinations for shrinkage control without severe compromise in strength. The results contribute valuable data for sustainable concrete design involving both recycled materials and alternative cementitious components.

Abstract in English:

ABSTRACT This study aims to develop a high-strength, high-performance self-compacting concrete through sustainable cement replacement using tailor-made supplementary cementitious materials. Two blends were formed: a hybrid slag blend consisting of ultrafine slag and ground granulated blast furnace slag in a 2:1 ratio with 1.5% gypsum, and a kaolinite-limestone blend combining calcined kaolin and limestone powder with different origins in a 2:1 ratio with 1% gypsum. Material selection was based on the chemical compatibility with the cement to ensure synergistic behavior. Durability characteristics were evaluated through water absorption, porosity, sorptivity, and rapid chloride penetration tests, while microstructural characteristics were analysed using SEM, XRD, and FTIR analyses. The HSB mix, at 30% replacement, significantly improved durability by reducing water absorption and porosity, and enhancing chloride resistance. The KLB mixes exhibited superior performance up to 50% replacement, with the volume of permeable voids decreasing from 2.71% to 1.35% at 28 days and from 2.62% to 1.05% at 90 days, respectively. The sorptivity index followed a similar declining trend, and chloride penetration in KLB at 50% mix remained negligible across all curing periods. XRD analysis confirmed a reduction of clinker phases, while FTIR revealed the formation of stable carboaluminate phases in KLB mixes, enhanced durability.

Abstract in English:

ABSTRACT This research assesses the improvement in concrete properties through the application of silica fume, nano-coated coarse aggregates, and steel fibres in 14 mixes. Mechanical tests were conducted at 7, 14, 28, and 90 days. Optimum mix M13, 85% cement, 15% silica fume, 80% coarse aggregates, 20% nano-coated aggregates, and 1.5% steel fibers, recorded the highest value of 103.25 MPa compressive, 9.305 MPa split tensile, and 10.433 MPa flexural strength at 28 days. Compared to normal concrete (M1), with values of 87.14 MPa, 7.853 MPa, and 8.805 MPa, respectively, M13 exhibited enhancement in strengths of more than 18% compressive, 18.5% tensile, and 18.5% flexural strength. Flexural response from experiment of the beams under load also exhibited less deflection in M13 (10.39 mm at 300 kN) than in M1 (11.38 mm), warranting enhanced ductility. Finite Element Analysis using ANSYS agreed with experimental trends with almost the same deflection values. X-ray Diffraction (XRD) analysis validated increased crystallinity and hydration of M13 with sharp peaks pointing to increased pozzolanic activity and greater microstructure than regular concrete. These results validate the efficiency of the combined application of silica fume, nano-modified aggregates, and steel fibres in the production of long-lasting, high-performance concrete for structural use.

Abstract in English:

ABSTRACT This study investigates the impact of internal geogrid confinement combined with fiber reinforcement on the axial behavior of concrete stub columns. Twenty small-scale circular stub column specimens were prepared, incorporating variations in the number of geogrid layers (one, two, and three) and fiber types (steel and polyvinyl alcohol). Results showed that geogrid confinement enhanced the axial load capacity, with double and triple layers improving the load by 10% and 8%, respectively, compared to unconfined specimens. Incorporating fibers further elevated performance, with PVA fibers yielding higher axial strength than steel fibers. Samples reinforced with geogrid and steel fibers exhibited superior fracture energy absorption, particularly in specimens with triple geogrid layers. Both geogrid and fiber-reinforced specimens demonstrated markedly improved load-deformation behavior and higher ductility indices. While geogrid confinement did not substantially increase the ultimate load capacity, it significantly enhanced ductility and energy absorption, suggesting that geogrids present a promising alternative to conventional confinement methods. Future work should focus on comparing uniaxial and biaxial geogrid effects and assessing performance under aggressive environmental conditions.

Abstract in English:

ABSTRACT This study explores the mechanical properties and environmental sustainability of basalt fiber-based Engineered Geopolymer Composites (BFEGC). Trial mixes, were developed and analyzed to determine their flowability and compressive strength, leading to the identification of an optimal formulation with a compressive strength of 55.34 MPa. The optimal mix was also found to exhibit split tensile and flexural strengths of 15.5 MPa and 5.13 MPa, respectively. Durability assessments of this mix were conducted through water absorption, sorptivity, and chloride penetration tests, confirming compliance with codal requirements. Thermal resistance evaluations were performed under varying conditions: low (300°C for 30 minutes), moderate (600°C for 20 minutes), and high (900°C for 15 minutes), followed by both rapid and gradual cooling. The minimal compressive strength degradation was observed for the optimal mix (Mix 4) at 300°C, with a decrease of only 19.40%. Additionally, the strain hardening behavior of BFEGC samples at elevated temperatures was studied, revealing microstructural stability up to 300°C during gradual cooling. TGA results indicated that the geopolymer matrix and basalt fibers work synergistically, resulting in a minor weight loss of only 2–5% at 300°C. The environmental impact of BFEGC was also assessed, demonstrating its potential to significantly reduce carbon emissions and embodied energy. BFEGC finds application in strengthening structural elements in fire-prone environments due to its thermal stability, low shrinkage, and strength retention at high temperatures.

Abstract in Portuguese:

RESUMO Compósitos poliméricos reforçados com fibras naturais destacam-se como alternativas promissoras aos materiais convencionais em aplicações estruturais, devido à boa relação resistência/peso, menor impacto ambiental e viabilidade econômica. Esta pesquisa avaliou a influência da orientação de fibras de juta nas propriedades mecânicas de compósitos com matriz de resina poliéster tereftálica. Foram analisadas quatro configurações de empilhamento: [0°/0°/0°], [0°/45°/0°], [0°/90°/0°] e [0°/tecido/0°]. As placas foram fabricadas por laminação manual, e corpos de prova extraídos para ensaios de tração. Avaliaram-se aspectos como força máxima, deslocamento na força máxima, limite de resistência e módulo de elasticidade. Foram selecionados tabs de compósito de fibra de vidro para garantir a correta aplicação da carga nos ensaios de tração. A orientação das fibras influenciou diretamente a resistência mecânica. A configuração [0°/0°/0°] obteve o melhor desempenho, com resistência à tração de 69,00 MPa, seguida de [0°/tecido/0°] (52,42 MPa), [0°/45°/0°] (47,17 MPa) e [0°/90°/0°] (42,31 MPa). A análise fractográfica evidenciou falhas por delaminação e propagação de trincas, mais intensas nas configurações com menor alinhamento das fibras à direção da carga. Logo, inferiu-se que o alinhamento das fibras com a direção do esforço aplicado maximiza a resistência mecânica e pode ser critério fundamental em projetos estruturais que utilizem materiais compósitos.

Abstract in English:

ABSTRACT Polymeric composites reinforced with natural fibers stand out as promising alternatives to conventional materials in structural applications, due to their good strength/weight ratio, lower environmental impact and economic viability. This research evaluated the influence of jute fiber orientation on the mechanical properties of composites with terephthalic polyester resin matrix. Four stacking configurations were analyzed: [0°/0°/0°], [0°/45°/0°], [0°/90°/0°] and [0°/fabric/0°]. The plates were manufactured by manual lamination, and specimens were extracted for tensile tests. Aspects such as maximum force, displacement at maximum force, resistance limit and modulus of elasticity were evaluated. Fiberglass composite tabs were selected to ensure the correct application of the load in the tensile tests. The orientation of the fibers directly influenced the mechanical strength. The [0°/0°/0°] configuration obtained the best performance, with a tensile strength of 69.00 MPa, followed by [0°/fabric/0°] (52.42 MPa), [0°/45°/0°] (47.17 MPa) and [0°/90°/0°] (42.31 MPa). The fractographic analysis showed failures due to delamination and crack propagation, which were more intense in the configurations with less fiber alignment with the load direction. Therefore, it was inferred that fiber alignment with the applied stress direction maximizes mechanical strength and can be a fundamental criterion in structural projects that use composite materials.

Abstract in English:

ABSTRACT The multi-functional polymeric EcoFlexFiber was used in the present research for its potential to improve concrete's performance in sustainable construction and real-time structural monitoring. A 2% volume fraction of EcoFlexFiber was incorporated into the concrete mixture, consisting of a load-bearing core fibre, a chitosan-based hydrogel sheath, and a polycaprolactone outer layer. This research reported notable enhancements in mechanical and durability properties of concrete. The compressive strength increased from 32.5 MPa at 7 days to 54.8 MPa at 28 days, and flexural strength improved from 3.21 MPa to 5.12 MPa over the same period. Split tensile strength also showed a very significant increase, from 3.20 MPa at 7 days to 5.01 MPa at 28 days. Water absorption tests showed reductions in porosity, both at 7 days by 6.57% and at 28 days by 12.32%, which indicated enhancement in durability against moisture influx. Thermal analysis showed satisfactory heat distribution; the surface achieves 100°C while stabilising at 85% in the core, which speaks of the thermal resistance characteristic of the fibre. These results reinforce the effectiveness of EcoFlexFiber in improving concrete mechanical properties, durability, and thermal performance, thus constituting a potential solution for sustainable and resilient construction.

Abstract in English:

ABSTRACT This study investigates the performance of Portland Slag Cement (PSC) concrete under different curing conditions, including normal curing and aggressive acid environments (hydrochloric and sulfuric acid), with and without the use of admixtures. The concrete mixes were evaluated for key properties such as compressive strength, saturated water absorption, effective porosity, resistance to acid and sulfate attacks, and chloride ion permeability. The results demonstrated that the inclusion of admixtures significantly enhanced the compressive strength, reducing water absorption and effective porosity, thus improving the overall density and durability of the concrete. At 28 days, the compressive strength of the concrete with admixtures was 29.18 MPa, compared to 26.77 MPa for conventional concrete. The admixtures also improved the resistance to sulfuric acid and sulfate attacks, as evidenced by reduced weight loss and strength loss compared to mixes without admixtures. Additionally, the RCPT results showed lower chloride ion permeability in mixes with admixtures, indicating enhanced durability against chloride-induced corrosion. Overall, the findings highlight the effectiveness of using admixtures in Portland Slag Cement concrete for improving durability and performance under aggressive environmental conditions.

Abstract in English:

ABSTRACT This study analyzes the influence of carbon black (CB) addition to a mixed adhesive based on vegetable oils, used in manufacturing Pinus sp. wood composite panels. To this end, test specimens were made to evaluate the following concentrations of carbon black (CB) was added at concentrations ranging from 0% to 100%. For each class of CB concentration, 6 specimens were made for physical and mechanical characterization in accordance with ABNT NBR 14810:2018 and used for microstructural analysis using Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) of the panels. As a result, the addition of CB to the vegetable oil-based mixed adhesive resulted in statistically higher average values for the mechanical properties of the panels with 30% CB, achieving the same level of significant increase as the panels with 60% CB and 100% CB in their strength values. According to the ABNT NBR 14810:2018 standards, the panels from 0% CB to 5% CB were classified as P6 (structural panels for use in severe load conditions, in dry conditions) and the panels from 10% CB to 100% CB were classified as P7 (structural panels for use in severe load conditions, in humid environments).

Abstract in English:

ABSTRACT With the rapid development of digitization and the Internet of Things, higher requirements have been put forward for the portability, process structure, material cost, sensitivity, and durability of sensors. This study proposes an MXene/PVA flexible self powered similar cicada wing triboelectric pressure sensor (CTPS) based on the principles of frictional electrification and electrostatic induction. Explored the film-forming performance and response sensitivity under different mass ratios of MXene to PVA. The manufactured sensor uses MXene/PVA composite material as the negative electrode material and graphene as the positive electrode material. In order to further improve the response sensitivity, the negative electrode material of the sensor is made into a similar cicada wing like biomimetic structure. The developed sensor can efficiently convert external mechanical forces and sound signals into electrical signal outputs. It achieves a sensitivity of 915.32 mV/N under a pressure of 0–5 N (frequency < 20 Hz), and a response sensitivity of 49.633 mV/Pa to 1 kHz sound waves. And the developed sensor is very lightweight, with a thin film thickness of only 30 um. At the same time, it can maintain constant voltage output in more than 6000 force cycle tests and 3 hours of sound cycle tests. The effectiveness and application potential of CTPS in the field of force and sound perception were verified through actual detection of sound signals from speakers.

Abstract in English:

ABSTRACT The increased use of concrete in modern construction contributes significantly to global warming and pollution-related health risks due to increased CO2 emissions. The use of nanoparticles in cement composites has attracted significant attention from researchers in recent years. In the field of material science, nanomaterial’s are an emerging field. This study investigates the flexural behavior of reinforced concrete beams incorporating nano-Alumina. Experimental tests and analytical models were conducted to evaluate performance improvements. To enhance the mechanical qualities of concrete, the experiment looks at nanoparticles such Nano Alumina (NA) and one of the useful cementitious elements in cement. In concrete, cementitious material partially replaces nanoparticles and pozzolanic material. To calibrate the strength parameters, a range of concrete mixes, including M30, M40, and M50, were cured for 28, 56, and 90 days in water. For mixtures hardened after 28, 56, and 90 days, compressive, split tensile, and flexural strengths were evaluated. An SEM analysis of the microstructure of mortar fragments present in concrete was conducted to determine how well nanoparticles fill concrete cavities. Due to the inherent brittleness and low tensile strength of conventional concrete, nano-Alumina (NA) was incorporated to enhance the mechanical performance of reinforced concrete beams. NA, owing to its high surface area and superior pozzolanic activity, refines the microstructure and improves load-bearing capacity. This study experimentally and analytically investigates the flexural behavior of NA-modified beams, demonstrating significant improvements in strength, ductility, and crack resistance.

Abstract in English:

ABSTRACT In modern machining operations, real-time identification of metallic alloy materials is critical to maintaining high-quality standards, reducing errors, and enhancing operational efficiency. This study introduces a robust machine learning and image processing framework designed for the rapid and precise identification of material batches during machining processes. The framework evaluates multiple machine learning models, including Support Vector Machine (SVM), Random Forest (RF), Naive Bayes (NB), k-nearest Neighbors (k-NN), Artificial Neural Networks (ANN), Radial Basis Function Neural Networks (RBFNN), and Logistic Regression, to determine their suitability under varying cutting conditions with high and low data volumes. The models were benchmarked on accuracy, training time, and inference speed to identify the most effective solution for real-time applications. SVM emerged as the most accurate model, achieving a precision of 91.2% with an inference time of 0.8 milliseconds, making it ideal for real-time tasks. ANN exhibited a comparable accuracy of 89.3% but suffered from a significantly higher inference time of 210.2 milliseconds, limiting its real-time feasibility. RF demonstrated quick training times but incurred a relatively high inference delay. Naive Bayes offered the fastest training and inference times with an accuracy of 79.8%, suitable for scenarios prioritizing speed over precision. This comparative analysis provides valuable insights for selecting the optimal machine learning model tailored to specific manufacturing requirements, fostering a data-driven approach to optimizing machining operations.

Abstract in English:

ABSTRACT This research assesses the mechanical and durability performance of geopolymer concrete (GPC) using fly ash, GGBS, and fiber reinforcements. 23 various GPC mixes were tested, each with varying amounts of GGBS (0–20%), steel fibers (0–2%), nylon fibers (0–2%), and glass fibers (0–2%). The best mix with 20% GGBS and 2% steel fibers produced the maximum compressive strength of 55.6 MPa. Sorptivity was lowest at 3.70 × 10−5 m/s1/2, reflecting minimum water absorption. The lowest RCPT value of 383 Coulombs categorized the mix as low-permeability concrete, providing excellent resistance to chloride ion penetration. Acid resistance tests registered negligible weight loss of 3.06%, while sulfate attack tests demonstrated minimum loss of strength of 3.60%. The optimized mix also demonstrated maximum resistance to saltwater exposure and reduced deterioration in aggressive environments. The research attests that geopolymer concrete with steel fibers and GGBS possesses enhanced mechanical strength and durability, making it a sustainable and high-performance material compared to ordinary concrete. These results demonstrate the potential of GPC in structural applications subjected to severe environmental conditions, advancing eco-friendly and durable construction materials.

Abstract in English:

ABSTRACT This study investigates the synergistic effects of recycled concrete powder (RCP) and steam curing on the properties of eco-concrete incorporating 50% recycled concrete aggregates (RCA). The goal is to determine the optimal RCP dosage and the most effective curing method. Portland cement was partially substituted with RCP at replacement levels of 10%, 20%, and 30%, and the impact on workability and compressive strength was evaluated under two curing regimes: water curing at 20 ± 1 °C and steam curing at 50 °C. The results indicate that 10% RCP improves workability by 53.4%, while higher replacement levels decrease is due to the increased water absorption capacity of RCP. Steam curing accelerates early-age strength development by activating the pozzolanic potential of RCP; however, excessive RCP content may compromise long-term strength when exposed to elevated curing temperatures. This study highlights a viable approach for incorporating recycled materials in concrete, contributing to sustainable construction practices by reducing cement consumption and promoting waste valorization.

Abstract in English:

ABSTRACT TiC/Fe cladding layers with different mass fractions of TiC were deposited on the surface of 45 steel by laser cladding technology, and their microstructure, microhardness, and corrosion resistance were investigated. Results show that the dendrites of the Fe35-fused cladding are composed of α-Fe solid solution, which is rich in Fe, Cr, Si, Mn, and Ni elements; the intercrystal is a cocrystal composed of α-Fe solid solution and (Cr, Fe)7C3, which is rich in Cr and C elements; the fused cladding is composed of columnar crystals, columnar dendrite crystals, and equiaxed crystals in the order from the bottom layer to the upper layer. In the 10% TiC-fused cladding, the bottom layer consists of columnar crystals, while the middle and upper layers are composed of equiaxed crystals. TiC is dispersed as fine, diffused small particles and small pieces within the matrix. Conversely, the fused cladding layers containing 20% and 30% TiC comprise equiaxed crystals, with TiC distributed in the matrix as agglomerated large particles and pieces. With an increase in TiC content, the bonding of TiC to the surrounding matrix diminishes. The 10% TiC-fused cladding exhibits the highest average microhardness, whereas the 20% TiC-fused cladding demonstrates the lowest average microhardness. The fused cladding without TiC addition displays the most positive corrosion potential, the lowest corrosion current density, the most stable passive film, and the best corrosion resistance. The corrosion resistance of the fused cladding diminishes following the addition of TiC; the higher the TiC content, the poorer the corrosion resistance of the fused cladding.

Abstract in English:

ABSTRACT Natural lignocellulosic (NLF) have emerged as sustainable reinforcements for mortars and concrete, however, fiber-matrix incompatibility remains a major challenge. This study investigates the use of sodium lignosulfonate (NaLS) to treat piassava (Attalea funifera) and sisal (Agave sisalana) fibers, aiming to improve their properties in cementitious composites. Fly ash (FA) and metakaolin (MK) were incorporated as supplementary cementitious materials (SCM) to lower matrix alkalinity and prevent degradation. For the first time, the impact of NaLS on the mechanical and ballistic performance of mortars with MK and FA as SCM was evaluated. Results showed that NaLS treatment improved fiber-matrix bonding, reduced porosity at the interfacial transition zone (ITZ), and mitigated fiber mineralization, particularly in sisal composites. NaLS-treated sisal fibers significantly enhanced ballistic energy absorption (+9.3%) compared to the unreinforced matrix, with no significant modifications in compressive and split tensile strength. In contrast, NaLS-treated piassava composites exhibited decreased tensile and compressive strengths, due to higher degree of fiber mineralization, with negligible change in ballistic performance. Microstructural analysis confirmed that the treated fibers promoted a denser ITZ and better interface quality, highlighting the critical role of fiber treatment in optimizing NLF-reinforced cementitious composites.

Abstract in Portuguese:

RESUMO Ligas de titânio, especialmente Ti-6Al-4V, são empregadas em aplicações biomédicas. No entanto, elementos como alumínio e vanádio podem apresentar efeitos citotóxicos, estimulando a busca por novas ligas. A liga Ti-45Nb apresenta elevado potencial para uso em implantes dentários, devido ao seu baixo módulo de elasticidade, alta resistência à corrosão e biocompatibilidade. Apesar dessas propriedades, estudos sobre sua usinabilidade são escassos. Este trabalho experimental teve como objetivo caracterizar a microestrutura, composição elementar, propriedades físico-químicas e mecânicas, bem como avaliar a usinabilidade da liga Ti-45Nb. Amostras foram obtidas em barras maciças e preparadas por metalografia. A microestrutura foi revelada e analisada por microscopia óptica, MEV/EDS e DRX. Ensaios de microdureza seguiram normas ASTM, com análise estatística por ANOVA. A usinagem foi realizada por torneamento CNC utilizando fresas e parâmetros específicos. Resultados mostraram uma microestrutura monofásica β, dureza média de 187 HV e módulo de Young de 62 GPa. A usinagem foi eficaz, obtendo rugosidade e acabamento comparáveis aos implantes convencionais em Ti-Cp. A geometria dos implantes fabricados correspondeu ao projeto original. Conclui-se que a liga Ti-45Nb apresenta propriedades adequadas para aplicação em implantes dentários. Estudos futuros devem explorar aspectos biológicos e parâmetros ideais de usinagem, visando otimizar o desempenho clínico da liga.

Abstract in English:

ABSTRACT Titanium alloys, especially Ti-6Al-4V, are used in biomedical applications. However, elements such as alumi-num and vanadium can present cytotoxic effects, stimulating the search for new alloys. The Ti-45Nb alloy has high potential for use in dental implants, due to its low modulus of elasticity, high corrosion resistance and biocompatibility. Despite these properties, studies on its machinability are scarce. This experimental work aimed to characterize the microstructure, elemental composition, physicochemical and mechanical properties, as well as to evaluate the machinability of the Ti-45Nb alloy. Samples were obtained in solid bars and prepared by metallography. The microstructure was revealed and analyzed by optical microscopy, SEM/EDS and XRD. Microhardness tests followed ASTM standards, with statistical analysis by ANOVA. Machining was performed by CNC turning using specific milling cutters and parameters. Results showed a single-phase β microstructure, average hardness of 187 HV and Young's modulus of 62 GPa. Machining was effective, obtaining roughness and finish comparable to conventional Ti-Cp implants. The geometry of the manufactured implants corresponded to the original design. It is concluded that the Ti-45Nb alloy presents suitable properties for application in dental implants. Future studies should explore biological aspects and ideal machining parameters, aiming to optimize the clinical performance of the alloy.

Abstract in Portuguese:

RESUMO As fibras naturais destacam-se como alternativas sustentáveis para reforço em compósitos, devido à disponibilidade, baixo custo e impacto ambiental reduzido. A presente investigação avaliou o comportamento mecânico de compósitos poliméricos reforçados por fibras de juta na forma de fios, fabricados por laminação manual com resina poliéster insaturada como matriz. As fibras comerciais, em tecido plano (T), foram desfiadas manualmente para formar arranjos unidirecionais com orientações específicas, resultando em oito configurações de empilhamento: 45°/0°/45°, 45°/45°/45°, 45°/90°/45°, 45°/T/45°, T/0°/T, T/45°/T, T/90°/T e T/T/T. Durante a fabricação dos laminados, manteve-se a fração mássica de fibra constante em 18% e a cura foi realizada à temperatura ambiente por sete dias. As amostras foram submetidas a ensaios de tração conforme parâmetros da norma ASTM D3039/D3039M, com aplicação de carga a 2 mm/min. Os resultados demonstraram variações significativas nas propriedades mecânicas em função da orientação das fibras, sendo que os arranjos T/0o/T e 45°/0°/45° apresentaram os melhores desempenhos em termos de resistência à tração (31,19 MPa e 31,16 MPa, respectivamente). A fractografia superficial permitiu correlacionar os modos de falha com a arquitetura dos compósitos fabricados, de modo a enfatizar a influência da simetria e da combinação de fibras alinhadas e tecidos nas propriedades dos materiais propostos.

Abstract in English:

ABSTRACT Natural fibers stand out as sustainable alternatives for reinforcement in composites due to their availability, low cost, and reduced environmental impact. This research evaluated the mechanical behavior of polymer composites reinforced with jute fibers in the form of yarns, manufactured by manual lamination with unsaturated polyester resin as the matrix. Commercial fibers, in flat fabric (T), were manually shredded to form unidirectional arrangements with specific orientations, resulting in eight stacking configurations: 45°/ 0°/45°, 45°/45°/45°, 45°/90°/45°, 45°/T/45°, T/0°/T, T/45°/T, T/90°/T, and T/T/T. During the manufacture of the laminates, the mass fraction of fiber was kept constant at 18%, and curing was performed at room temperature for seven days. The samples were subjected to tensile tests according to the parameters of ASTM D3039/D3039M, with load application at 2 mm/min. The results showed significant variations in mechanical properties depending on the orientation of the fibers, with the T/0o/T and 45°/0°/45° arrangements showing the best performance in terms of tensile strength (31.19 MPa and 31.16 MPa, respectively). Surface fractography allowed the failure modes to be correlated with the architecture of the manufactured composites, emphasizing the influence of symmetry and the combination of aligned and woven fibers on the properties of the proposed materials.

Abstract in English:

ABSTRACT The poor efficiency caused by the quick charge recombination limited the most prominent photocatalyst g-C3N4’s photocatalytic activity. This work effectively synthesized highly efficient g-C3N4, and (CuS & CuS/g-C3N4 heterojunction composites) by utilizing simple thermal treatment and microwave-assisted methods, respectively. The synthesized materials were analyzed by XRD, UV-Vis DRS, FTIR, FESEM, PL, XPS, and HRTEM analysis. The CuS/g-C3N4 composites was validated by XRD analysis, which showed changes in peak intensity as the g-C3N4 content increased. When compared to the individual components, the CuS/g-C3N4 composites had a smaller band gap, which improved their absorption of visible light, according to UV-Vis DRS. The produced materials’ distinctive stretching vibrations were detected by FTIR spectra, and their emission characteristics were revealed by PL spectra. CuS nanospheres implanted on g-C3N4 nanosheets were visible in FESEM pictures. The components C, N, O, S, and Cu, as well as their chemical states, were verified by XPS analysis of the 1:3 composite. The intricate microstructure and interface morphology of the composites were further clarified by HRTEM. Using a 250W halogen lamp in a handmade photocatalytic reactor, the composites’ photocatalytic effectiveness was assessed for the degradation of malachite green (MG) dye in aqueous solution when exposed to visible light. By creating CuS/g-C3N4 heterojunction composites, this work seeks to improve the photocatalytic efficiency of g-C3N4, which is generally hampered by rapid charge carrier recombination. The outcomes showed that the CuS/g-C3N4 heterojunction performed better photocatalytically than either CuS or g-C3N4 alone. After 120 minutes, the 1:3 composite showed the best degrading efficiency of all the CuS/g-C3N4 ratios, higher than both CuS/g-C3N4 (1:2) at 73.5% and CuS/g-C3N4 (1:1) at 58.9%. On the other hand, the efficiency of pure MG, g-C3N4, and CuS were just 0.8%, 22.7%, and 60.1%, respectively. Rapid charge carrier recombination considerably reduces the photocatalytic efficacy of g-C3N4. CuS/g-C3N4 heterojunction composites were created as a solution, which improved photocatalytic efficiency. In comparison to individual components and various composite ratios, the optimized 1:3 CuS/g-C3N4 composite demonstrated improved degradation of malachite green (MG) dye under visible light. This improvement is ascribed to the development of a heterojunction interface between CuS and g-C3N4, which leads to enhanced charge separation and prolonged visible-light absorption. The research study indicates that heterojunction engineering can effectively modify photocatalytic characteristics, with encouraging prospects for wastewater treatment and environmental remediation applications.

Abstract in English:

ABSTRACT The increasing expansion of urban gas pipeline networks in China has heightened the need for effective and environmentally friendly plugging solutions. Traditional mechanical plugging methods often result in incomplete sealing, high costs, and potential damage to pipeline integrity. To overcome these problems, the project seeks to create a self-degrading hydrogel for the temporary plugging of pipes, based on acrylic acid, acrylamide, and PA-1 as crosslinkers, along with using ammonium persulfate and sodium bisulfite as a redox initiator system. Single-factor experiments were used to examine how factors like polymer concentration, enzyme concentration, crosslinker concentration and temperature influence the gel strength, the time to gel, and when the gel breaks down. Optimized formula accelerated Gelation and completely degraded the gel at normal or heated room temperature. Applying 50 kPa pressure, the gel was able to maintain a seal, showing this material is suitable for medium- and low-pressure pipes. The research discoveries point to this new gel, which is eco-friendly and cost-effective, as a prospective medicine for gas pipeline repair and use in gas storage and transportation. Improving the gel’s effectiveness in different jobs and making it ready for mass industrial application should be the main goals of upcoming research.

Abstract in English:

ABSTRACT The CrN-Cu coatings were synthesized on titanium substrates via multi-arc ion plating. A discontinuous Cu layer was successfully incorporated into the CrN coating by controlling the deposition parameters to improve the coating structure and endow the coating antibacterial properties. The total thickness of the CrN-Cu coating was 5.53 μm. The CrN-Cu coating consists of two phases, CrN and Cu, with a discontinuous Cu layer in the form of clusters surrounded by differently oriented CrN grains. X-ray photoelectron spectroscopy revealed the chemical bonding states of Cr-N and Cr-O, as well as those of metallic copper and copper oxide. The addition of copper reduced the residual compressive stress from 1.49 GPa to 1.00 GPa, increased the interfacial bond strength (critical load LC3 from 28.62 N to 61.73 N), and reduced the coefficient of friction from 0.43 to 0.38. Despite the slight decrease in nanohardness owing to the soft copper interlayer, the coating demonstrated excellent antibacterial efficacy owing to the controlled release of copper ions (0.240 mg/L after 24 h of immersion), reaching 99.75% and 99.87% for E. coli and S. aureus, respectively.

Abstract in English:

ABSTRACT In this study, electrospun polycaprolactone (PCL) mats containing 10% Brazilian red propolis extract were developed and evaluated after exposure to gamma irradiation at 29.91 kGy. The objective was to assess whether irradiation affects the physicochemical properties, structural integrity, thermal behavior, and bioactive compound stability of the composite. A range of characterization techniques was employed, including scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). All measurements were performed in triplicate (n = 3) and expressed as mean ± standard error of the mean. SEM (100 measurements) revealed that the morphology of the nanofibers remained preserved, with diameters of 1173 ± 360 nm (non-irradiated) and 1182 ± 340 nm (irradiated). FTIR results confirmed the chemical stability of PCL. Crystallinity increased from 52.7 ± 1.2% to 85.8 ± 2.5%, and DSC/TGA showed no change in degradation profile. Flavonoid content (15.4 ± 0.3 vs. 15.0 ± 0.4 mg QE/g) and antioxidant activity were maintained. These findings confirm that gamma irradiation preserves both structure and functionality, supporting its use in sterilizable biomaterials based on natural products.

Abstract in English:

ABSTRACT Strength and durability characteristics of the concrete partially substituted with waste by-products have been reported. The optimal cement replacement percentage with cement sludge and metakaolin has been experimentally verified. The plausibility of replacing cement sludge and metakaolin with cement in concrete has been assessed based on test results. The percentage proportions of cement sludge were varied between 2% and 10%, increasing in 2% increments by weight of cement, with the optimal content identified as 4%. Subsequently, the metakaolin content was tested in the range of 3% to 15% by weight of cement, with the optimal proportion found to be 9% when combined with 4% cement sludge. An empirical model has been established between the 28-day compressive and flexural strength to assess the strength. The microstructure of cement sludge and metakaolin incorporated mix has been evaluated.

Abstract in English:

ABSTRACT Waste recycling and reuse from the industries are effective way to maintain and enhance the sustainable environment. To investigate the optimal percentage of replacement of cement with industrial waste materials such as Alccofine and calcined clay and the addition of polypropylene fibre as an additive to concrete are the novelty of the present study. The use of polypropylene fibre in concrete is to improve its structural performance and sustainability. Polypropylene fibre was chosen for its excellent tensile strength, chemical resistance, low cost and cementitious material compatibility and also very good in decreasing cracks, enhancing durability. The study followed 15% and 30% replacement of Alccofine and calcined clay for cement and with 2% of fiber were added to enhance the mechanical and durability properties of M40. The study found that, 15% of replacement is optimal percentage of Alccofine and calcined to increase the mechanical properties such as 19.38% of compressive strength, 15.24% of bending strength and 14% of tensile strength. The microstructural studies confirmed that the increase in strength and durability of the concrete is due to the thinness of the Alccofine material and its ability to fill voids.

Abstract in English:

ABSTRACT Triply periodic minimal surface (TPMS) structures have gained significant interest due to their excellent mechanical characteristics and diverse range of applications across various fields. This study systematically designs and analyzes uniform and gradient porous structures based on Primitive and Gyroid TPMS geometries. The samples were fabricated using fused deposition modeling (FDM) with polylactic acid (PLA). Their morphologies were characterized via optical microscopy and micro-computed tomography (micro-CT), and quasi-static compression tests were performed under controlled conditions to evaluate their mechanical properties. The results demonstrated that the fabricated pore characteristics closely matched with the design parameters. For the uniform structures, yield strength decreased from 11.26 MPa at 30% porosity to 2.24 MPa at 50% porosity, and the elastic modulus decreased from 309.8 MPa to 167.1 MPa as porosity increased from 30% to 50%. At the same porosity, uniform structures exhibited higher yield strength than gradient structures. Additionally, an empirical equation derived from the Gibson-Ashby model was introduced to predict the compressive behavior of porous structures based on their relative density. These findings provide essential guidance for designing lightweight structures with enhanced mechanical properties, highlighting the potential of TPMS porous structures for advanced engineering applications.

Abstract in Portuguese:

RESUMO A análise mecanística de pavimentos consiste na determinação das respostas estruturais com base nos princípios da mecânica, calculando tensões, deformações e deslocamentos considerando as propriedades dos materiais constituintes, a geometria da estrutura, as condições de contorno e o carregamento aplicado. Essa abordagem é fundamental para compreender o comportamento dos pavimentos sob diferentes condições de solicitação, permitindo a previsão de falhas e a otimização do desempenho estrutural. A deformabilidade dos materiais que compõem o pavimento e suas relações tensão-deformação são aspectos críticos para a análise estrutural. Assim, a importância de ensaios de módulo de resiliência (MR) e deformação permanente (DP) para avaliar o comportamento das misturas. Esses ensaios fornecem dados essenciais sobre a resposta elástica e plástica dos materiais, que influenciam diretamente a capacidade do pavimento de suportar cargas repetidas ao longo do tempo. Neste contexto, este estudo avaliou o desempenho mecânico de um solo laterítico fino estabilizado com cal e polímero acrílico industrial, seguindo a Metodologia de Classificação Universal de Solos Lateríticos (CUSL). Foram realizados ensaios de CBR, resistência à tração e resistência à compressão simples e módulo de resiliência. A estabilização com cal, utilizando o teor mais econômico, proporcionou ganhos significativos de resistência, com o melhor desempenho observado após 28 dias de cura. Os resultados evidenciaram que o tempo de cura influencia diretamente a resistência dos solos estabilizados, com períodos mais prolongados resultando em melhorias substanciais nas propriedades mecânicas. Entre os teores de polímero estudados, a mistura SLC + PL5% destacou-se pelo melhor desempenho em todas as propriedades mecânicas avaliadas, reforçando a viabilidade técnica do uso de estabilizantes alternativos na engenharia de pavimentos.

Abstract in English:

ABSTRACT The mechanistic analysis of pavements involves determining structural responses based on the principles of Mechanics, calculating stresses, strains, and displacements while considering the properties of constituent materials, the geometry of the structure, boundary conditions, and the applied loading. This approach is fundamental for understanding pavement behavior under different loading conditions, enabling the prediction of failures and the optimization of structural performance. The deformability of the materials composing the pavement and their stress-strain relationships are critical aspects of structural analysis. The importance of resilient modulus (MR) and permanent deformation (PD) tests to evaluate the behavior of mixtures. These tests provide essential data on the elastic and plastic responses of materials, which directly influence the pavement's ability to withstand repeated loads over time. In this context, this study evaluated the mechanical performance, of a fine lateritic soil stabilized with lime and industrial acrylic polymer, following the Universal Classification Methodology for Lateritic Soils (CUSL). Tests were conducted for CBR, tensile strength, unconfined compressive strength and resilient modulus. Stabilization with lime, using the most economical content, provided significant strength gains, with the best performance observed after 28 days of curing. The results demonstrated that curing time directly influences the strength of stabilized soils, with longer periods resulting in substantial improvements in mechanical properties. Among the polymer contents studied, the SLC + PL5% mixture stood out for its superior performance in all evaluated mechanical properties, reinforcing the technical feasibility of using alternative stabilizers in pavement engineering.

Abstract in English:

ABSTRACT Concrete durability is a fundamental criterion influencing the long-term performance of civil engineering infrastructure. Conventional durability enhancement strategies typically rely on synthetic chemical admixtures, which often entail environmental and ecological drawbacks. This study investigates the efficacy of bio-based admixtures—specifically a cross-linked formulation of cassava starch and xanthan gum—as sustainable modifiers to improve concrete durability. The admixtures were incorporated into concrete at three dosages (0.5%, 1%, and 1.5% by weight of cement), and specimens were exposed to 5% concentrations of H2SO4, NaOH, and NaCl solutions under controlled conditions for up to 90 days. Durability performance was assessed through compressive strength retention, mass variation, and permeability, with the latter evaluated using the Rapid Chloride Permeability Test (RCPT) in accordance with ASTM C1202. The 1.5% admixture blend demonstrated the most favorable performance, showing minimal strength degradation, reduced mass loss, and significantly decreased chloride ion penetrability. Microstructural analysis suggested improved pore refinement and enhanced interfacial transition zones, contributing to the material’s resistance against chemical ingress. The results validate the potential of these natural admixtures to function as sustainable substitutes for conventional additives, delivering superior resistance to chemical attack while reducing ecological impact. This research advocates for the integration of bio-derived polymers in concrete technology to advance green infrastructure without compromising structural integrity.

Abstract in English:

ABSTRACT In this research an effort is made to investigate the machining of Incoloy 800H Super alloy which is hard to machine material due to its rapid hardening property. Laser textured cryogenically treated cutting inserts and vegetable oil enriched with ZnO nano particles through Minimum Quantity Lubrication (MQL) was used. Turning experiments were performed based on L27 Orthogonal Array (OA). Cutting speed, feed rate, and depth of cut were the input parameters. Surface roughness, cutting force, micro hardness, tool-tip temperature, power and material removal rate were the responses measured. Taguchi based Grey Relational Analysis and Analysis of Variance were used to optimize and find the most influencing parameter. The results revealed that the optimal machining conditions were cutting speed at 35 m/min, feed rate at 0.06 mm/rev and depth of cut at 0.5 mm for the multiple-characteristic performances and it was improved by 4.87%. Microhardness, Tool-tip temperature and Power were reduced during machining to 1.31%, 4.53% and 2.10% respectively. Moreover, ZnO nanoparticles enriched base fluid gives better performances in terms of surface roughness, tool wear and cutting force. Furthermore, the White Light Interferometer (WLI) and Scanning Electron Microscopy (SEM) were used to study the machined surface topography and tool wear analysis.

Abstract in English:

ABSTRACT This study investigates the improvement of mechanical properties and durability of Crushed Recycled Concrete (CRC) and Reprocessed Material Concrete (RMC) by dual nano-strengthening immersion treatment with Nano-SiO2 and Nano-Al2O3 nanoparticles. The main goal is to enhance the structural quality and applicability of recycled concrete for high-strength; crack-resistant infrastructure use by attacking the Phase Transition Layer (PTL) between recycled aggregates and cement paste. The research uses a two-step immersion procedure in which samples are immersed for 48 hours in a 5% Nano-SiO2 sol solution and 48 hours in a 2% Nano-Al2O3 slurry, allowing for even nano-material absorption at room temperature. Extensive experimental testing was undertaken, comprising compressive and flexural strength tests, bond strength evaluation through pull-out tests, Mercury Intrusion Porosimetry (MIP) for porosity examination, and micro-hardness tests to assess the densification of the PTL. Results show remarkable enhancements in treated samples as opposed to untreated controls: compressive strength enhanced from 21.5–23.0 MPa to 29.5–31.0 MPa in CRC, and from 19.9–20.8 MPa to 27.8–29.1 MPa in RMC. Flexural strength exhibited improvements of up to 17% for RMC and 13% for CRC, while bonding strength for steel reinforcement was improved appreciatively. Microstructure analysis verified the decreased porosity and densification of the PTL as the main factors for the overall improved mechanical properties. Simulation results were in good agreement with experimental data, verifying the efficiency of the nano-strengthening treatment. This research illustrates the promise of incorporating nano-materials into recycled concrete as a viable step towards sustainable high-performance materials for key infrastructure.

Abstract in English:

ABSTRACT To improve the firefighting performance of aqueous film forming foam (AFFF), a new AFFF formulation containing nano silicon (SiO2) particles was developed in this study. Nano-SiO2 (average particle size: 105 nm) was synthesized and incorporated into the standard AFFF formula at a concentration of 5%. The physicochemical properties of modified AFFF were systematically analyzed, and then the new firefighting material was tested in a simulated fire environment to analyse its firefighting performance. The firefighting time of new firefighting materials for solid combustibles, liquid substances, and chemical fires was significantly improved compared to the unoptimized materials, ranging from 0.9 to 1.5 minutes, 0.7 to 1.3 minutes, and 1.1 to 2.3 minutes, respectively. After 7 days of exposure, the quality loss of SiO2-AFFF on steel (ASTM A36) was 0.9%, while the quality loss of the control AFFF was 9.8%, indicating a significant reduction in corrosiveness. Acute toxicity testing showed a significant reduction in toxicity compared to the control group. These results indicate that the addition of nano-SiO2 significantly raises the fire extinguishing performance of AFFF and reduces its corrosiveness, providing a potential pathway for the development of more effective and safer AFFF firefighting materials.

Abstract in English:

ABSTRACT The extensive discharge of tannery effluents containing heavy metals into the environment severely threatens ecosystems and public health. This study assesses the adsorption efficiency of Delonix regia as a sustainable adsorbent for removing heavy metals from tannery effluents. Operating conditions, including pH, interaction time, adsorptive dosage, and preliminary metal attentions, were systematically enhanced to enhance the adsorption process. Analytical results reveal that heavy metals such as Chromium (Cr3+), Nickel (Ni2+), Lead (Pb2+), Cadmium (Cd2+), Iron (Fe3+), and Zinc (Zn2+) frequently exceed permissible limits set by WHO and US-EPA standards in effluents, with Cr and Cd surpassing limits in 75% and 50% of studies, respectively. The adsorption experiments demonstrate that Delonix regia effectively reduces metal concentrations to acceptable levels under optimal conditions, with higher adsorption capacities for Cr and Pb. The adsorbent’s recovery potential was assessed using desorption techniques, ensuring its reusability and economic feasibility. Furthermore, the study highlights the influence of effluents’ physicochemical properties (e.g., temperature, turbidity, conductivity) on adsorption efficiency, providing insights into real-world application scenarios. Comparative research with present adsorbents confirms the viability of Delonix regia as an ecological and profitable replacement for heavy metal cleanup. This paper underlines the importance of including recovery mechanisms and maximising operational parameters to improve the sustainability of effluent treatment systems. By offering scalable solutions for companies wishing to follow rigorous environmental policies, findings help to raise knowledge of green remedial tactics.

Abstract in English:

ABSTRACT Silver amalgams are used to fill damaged teeth, while titanium (cp Ti and Ti-6Al-4V) is used in dental implants due to its biocompatibility and osseointegration capacity. The interaction of these materials in the oral cavity, through saliva, can generate galvanic corrosion and release metallic ions harmful to the health of users. This study evaluates the corrosion resistance of galvanic couples formed by high-copper silver amalgam (Duralloy) and titanium (CP Ti and Ti-6Al-4V) using electrochemical methods (potentials, current densities, Evans diagrams, and Mansfeld correction formulas in aerated artificial saliva). The results indicate that the combination of Duralloy with CP Ti and Ti-6Al-4V presents the highest corrosion resistance, which is corroborated by long-term current density curves.

Abstract in Portuguese:

RESUMO Este trabalho investigou a eficiência da adesão entre fibras de polietileno tereftalato (PET) reciclada e a matriz cimentícia, visando determinar o comprimento crítico de ancoragem das fibras de PET em concretos reforçados. Ensaios de Pull out foram realizados para avaliar a interação entre fibra-matriz e a tensão máxima de cisalhamento. Os resultados indicaram que fibras de PET com comprimento de ancoragem de 20 e 30 mm apresentaram escorregamento, enquanto as fibras de PET com 40 e 50 mm mostraram deformação sem escorregamento, evidenciando a necessidade de um maior comprimento de embutimento para melhorar a ancoragem das fibras de PET e uma melhor distribuição de tensões. A análise por Microscopia Eletrônica de Varredura (MEV) revelou que a superfície lisa das fibras de PET prejudica a aderência com a matriz, sugerindo que para a utilização deste material devem ser adotados maiores comprimentos de embutimento, melhoram o desempenho do concreto reforçado. O estudo concluiu que o comprimento crítico mínimo de ancoragem foi de 40 mm a fim de otimizar a transferência de tensões.

Abstract in English:

ABSTRACT This study investigates the adhesion efficiency between recycled PET fibers and the cementitious matrix, aiming to determine the critical anchorage length of the fibers in reinforced concrete. Pull-out tests were performed to evaluate the fiber-matrix interaction and the maximum shear stress. The results indicated that fibers with anchorage lengths of 20 and 30 mm presented slippage, while fibers of 40 and 50 mm showed deformation without slippage, evidencing the need for a longer embedment length to improve anchorage and stress distribution. Scanning Electron Microscopy (SEM) analysis revealed that the smooth surface of the PET fibers impairs adhesion with the matrix, suggesting that for the use of this material, longer embedment lengths improve the performance of reinforced concrete. The study concludes that the minimum critical anchorage length is 40 mm for better stress transfer.

Abstract in English:

ABSTRACT To study the fatigue properties of reinforced concrete (RC) T-beams strengthened with a composite of prestressed steel wire ropes embedded in polyurethane cement (PSWR-PUC), which is an innovative reinforcement method, two RC beams without strengthening, three RC beams with a composite of prestressed steel wire ropes embedded in polymer mortar (PSWR-PM) and three RC beams with PSWR-PUC were designed. Some key parameters, such as the material into which the wire rope is imbedded, the fatigue loading, and the tension of steel wire ropes, are discussed. The experimental results show that PSWR-PUC reinforcement can significantly improve the monotonicity and fatigue performance of RC T-beams. The PSWR-PUC strengthening can significantly reduce beam deflection and steel bar stress. Under the same load, the maximum strain and strain range of PSWR-PUC reinforced beams are significantly smaller than those of PSWR-PM reinforced beams. Due to the excellent properties of polyurethane cement composite with high strength, high bond, and high toughness, the cracking and peeling phenomenon of polymer mortar in PSWR-PUC reinforced beams did not occur, which can improve the fatigue life of beams by reducing the stress of steel bars. Due to the cracking, falling off, and peeling of polymer mortar, the bonded prestressed wire rope becomes unbonded pre-stressed wire rope, which redistributes the stress of the beam and further increases the stress of the steel bars.

Abstract in English:

ABSTRACT In this investigation, a performance analysis of a liquid desiccant-based dehumidification system was conducted by integrating a particle swarm optimization (PSO) algorithm and an artificial neural network. Experimental data are collected through past studies on falling film towers for flat plate and cylindrical surfaces, covering a wide range of liquid desiccant and air operating conditions. The neural network is fine-tuned through the use of the PSO algorithm. This optimization aims to enhance the accuracy of predicting the moisture absorption rate, change of specific humidity and dehumidification effectiveness of a liquid LiCl (Lithium chlorite) desiccant system. The effectiveness is contingent on various working parameters, including mass flow rate of moist air, mass flow rate of liquid LiCl solution desiccant, inlet air temperature, and relative humidity of inlet air, inlet temperature LiCl solution desiccant and desiccant concentration. The present ANN-PSO algorithm predicts the changes of absolute specific humidity, moisture absorption rate of water vapour from air and effectiveness of the dehumidification system. The present model precisely predict the performance parameters with R2 = 0.9989.

Abstract in English:

ABSTRACT Ensuring improved strength and durability in concrete has become significant in modern infrastructure. This study presents Artificial Neural Networks for predictive analysis to investigate how glass fibers, coir fibers, and nanosilica affect the mechanical properties of concrete. Incorporating 3% nanosilica with varying proportions of glass, coir fibers (0.3 – 3%) revealed significant improvement in the concrete’s performance. At 1.5% concentration glass fiber increased compressive strength by 15%, flexural strength by 35.6%, and tensile strength by 43.5%. Similarly, 1.2% concentration, coir fibers improved these properties by 9%, 16.4%, and 32.5% respectively. The mean square propagation, testing, training, validation results are used to prepare the ANN model. For glass fibers, the results are 0.8772, 0.9734, 0.9828, and 0.9563, and the optimal validation results is 0.0107 at epoch 10; for coir fibers, the results are 0.9743, 0.9949, 0.9941, and 0.9909, and the optimal validation results is 0.0220 at epoch 8 correspondingly. To further validate the model’s reliability, additional statistical metrics are Willmott’s Index of Agreement was found to be 0.9953, the Nash–Sutcliffe Efficiency was 0.9814, and the percent bias was –0.0083%. These results confirm the robustness and practical applicability of the proposed ANN model in predicting concrete strength parameters with high fidelity.

Abstract in English:

ABSTRACT Brazilian Code NBR 7190:2022 for timber structures design adopts a simplified approach for determining characteristic values from small samples, based on the Centered Estimator Method assuming data normality. However, there is a gap in literature regarding its accuracy compared to the widely used approach in interna-tional codes, which defines the characteristic value as the 5th percentile of a fitted statistical distribution. This study evaluated strength and stiffness properties in tension and compression parallel to grain of five Brazilian tropical species, comparing the characteristic values obtained by NBR 7190-3:2022 with those derived from the 5th percentile of normal, lognormal, two-parameter Weibull, three-parameter Weibull, Gamma, and Logistic distributions. Results indicated that the normal distribution was adequate in most cases, while three-parameter Weibull distribution demonstrated greater flexibility in fitting, in capturing skewness in strength/stiffness distributions but also resulted in less conservative characteristic values. Additionally, it was observed that NBR 7190-3:2022 method led to characteristic values of mechanical properties, on average, 7% to 29% higher than those obtained from the 5th percentile of the analyzed statistical distributions. These results suggest the need to revise the Centered Estimator Method in NBR 7190-3:2022, to improve estimating characteristic value reliability.

Abstract in Portuguese:

RESUMO O uso de semicondutores orgânicos representa uma abordagem promissora no avanço da eletrônica orgânica, setor em rápida expansão tecnológica. A busca por materiais com propriedades otimizadas é estratégica para o desenvolvimento de dispositivos mais eficientes. Neste contexto, investigamos as propriedades estruturais e eletrônicas do cristal de elipticina, um alcaloide com reconhecida atividade anticâncer, mas ainda inexplorado como semicondutor orgânico promissor para aplicação em dispositivos eletrônicos. Utilizamos cálculos de primeiros princípios baseados na Teoria do Funcional da Densidade (DFT) para simular a estrutura molecular isolada e o empacotamento cristalino, com ênfase nas interações intermoleculares. Para isso, comparamos os funcionais LDA-PZ, GGA-PBE e GGA-PBE-vdW, sendo este último adotado como referência por incluir correções empíricas de van der Waals. Os resultados mostraram que o funcional GGA-PBE-vdW reproduz melhor as distâncias intermoleculares observadas experimentalmente, favorecendo condições para acoplamento eletrônico mais eficiente. As simulações revelaram ainda que o empacotamento cristalino reduz significativamente o gap de energia em relação à molécula isolada. A análise da densidade de estados (DOS) e das estruturas de bandas, inéditas na literatura para o cristal de elipticina, indicou forte contribuição dos orbitais dos átomos de nitrogênio e do grupo NH para o topo da banda de valência, o que sugere caminhos preferenciais para o transporte de carga. Essa assinatura eletrônica distingue a elipticina de outros semicondutores orgânicos convencionais e pode estar associada a elevadas mobilidades de portadores. Os resultados reforçam o potencial da elipticina como material funcional em dispositivos eletrônicos orgânicos de alto desempenho.

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ABSTRACT Organic semiconductors are a promising route for advancing organic electronics, a field experiencing rapid growth in performance and applications. The identification of materials with finely tuned optoelectronic properties is therefore crucial to realize more efficient devices. In this work, we present a first-principles density functional theory study of the structural and electronic properties of ellipticine crystal, a biologically active alkaloid hitherto unexplored as an organic semiconductor. Both the isolated molecule and its crystalline packing were modeled using the LDA-PZ, GGA-PBE and GGA-PBE-vdW exchange-correlation functionals, the latter incorporating empirical van der Waals corrections. Our results demonstrate that GGA-PBE-vdW most accurately reproduces experimental intermolecular distances, creating favorable conditions for electronic coupling. We also find that crystal packing leads to a significant narrowing of the fundamental band gap compared with the monomer. Most notably, novel band-structure and projected density of states analyses reveal a dominant contribution of nitrogen and NH-group orbitals at the valence-band maximum, a feature that distinguishes ellipticine from conventional organic semiconductors and has not been reported before. This electronic signature suggests preferred pathways for charge transport and may account for elevated carrier mobilities. Taken together, these findings establish ellipticine as an exceptional candidate for high-performance organic electronic devices and highlight the necessity of van der Waals-corrected DFT in accurately capturing the behavior of molecular semiconductor systems.

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ABSTRACT The growing amount of electronic waste or E-Waste poses a serious threat to the environment worldwide and calls for re-purposing and sustainable management techniques. The goal of this research is to create high-performance energy-efficient materials with optimized morphological and mechanical properties by usieng e-waste as a filler material in PET-based composites. Using a twin-screw extruder cleaned and shredded, polyethylene terephthalate (PET) was combined with e-waste fractions in different weight percentages (wt.%), such as 0 wt.%, 20 wt.%, 40 wt.%, 60 wt.%, 80 wt.%, and 100 wt.%, to create composites which were then injected. Mechanical properties such as impact, flexural, and tensile strength were evaluated, while wear was assessed as a tribological property, to determine the stability of the composites. Additionally, statistical techniques such as Regression analysis were conducted to known the composite performance. The results demonstrated significant mechanical enhancements: tensile strength increased from 55.2 MPa to 72.8 MPa, flexural strength rose from 80.5 MPa to 100.4 MPa, and impact resistance improved from 18.5 J/m to 28.6 J/m as the e-waste content increased from 0% to 100%. Wear rate reduced from 0.025 mm3/Nm to 0.015 mm3/Nm, and hardness improved from 72 to 87 Shore D. Regression analysis showed high predictive accuracy with R2 values ranging from 0.93 to 0.99, confirming strong correlations between filler content and mechanical performance. Finally Morphological analysis such as Elemental Energy dispersive X-ray analysis (EDAX) and Scanning Electron Microscopy (SEM) analysis were assessed for finding consistent filler dispersion and bonding of the composites. The results demonstrated that e-waste incorporation enhanced specific mechanical properties, with SEM and EDAX analyses verifying adequate interfacial adhesion. This research highlights the potential of recycling e-waste into sustainable PET-based composites, addressing environmental challenges while advancing industrial material development.

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ABSTRACT The mechanical, microstructure, wear and electrochemical corrosion properties of Ti6Al4V/xTiB2-xTiC (x = 0, 2.5, 5, and 7.5 vol.%) hybrid composites, produced by powder metallurgy, were studied in relation to their reinforcement percentage. Initially, mechanical investigations were carried out to assess the mechanical attributes of the composites. Additionally, the wear and friction behavior of the composites was examined using a pin-on-disk apparatus under various conditions. The Scanning electron microscope and X-ray diffraction analysis were carried out to understand the microstructural changes and elemental compositions of the specimens. Electro Chemical Corrosion experiments were conducted under simulated body environments, such as 37 °C and simulated body fluid. The findings revealed that the homogeneous distribution of reinforcements into the titanium (Ti) matrix, led to significant microstructural changes, achieving maximum hardening of the Ti6Al4V with 5 vol.% TiB2-TiC. In comparison to the Ti6Al4V alloy, the Ti6Al4V/5%TiB2 & 5% TiC composite exhibits a 48% increase in hardness and a 18% decrease in porosity. According to the corrosion test findings, the Ti6Al4V/5% TiB2 & 5%TiC hybrid composites exhibited superior corrosion behaviour than the alloy, with a corrosion current density of 1.0 × 10–6 A/cm2. These results provided valuable insights into the relationship between composition, microstructure, and the enhanced corrosion potentials of the alloy and composites.

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ABSTRACT This work evaluates the technical viability of using green composites to build small boats, such as those used by riverine communities in the Amazon region. A 730 mm-long boat was constructed using a sandwich lamination technique. This miriti wood boat was coated with epoxy resin reinforced with two layers of unidirectional jute fabric on both the interior and exterior. The sandwich lamination provided benefits such as increased stiffness, impermeability, and a standardized production process. Fourteen strain gauges were installed on the boat's hull to measure strains in the key regions under various loads. The boat was experimentally tested using a bending test with bi-supported conditions. Additionally, a numerical model was developed using the finite element software ANSYS to simulate the same conditions as the experimental test. To enhance the accuracy of the numerical model, a code was developed using ANSYS Parametric Design Language to account for the anisotropic behavior of the jute composite. The numerical model was validated by comparing the experimentally measured strains with the calculated strains from the simulation.

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ABSTRACT The rising global demand for sustainable construction materials has catalyzed the exploration of industrial byproducts in concrete production, aiming to reduce environmental impact while maintaining structural integrity. Among these byproducts, WFS and BA are two prominent solid waste streams generated from the metal casting and thermal power sectors, respectively. Their potential as partial replacements for natural fine aggregates in concrete has gained increasing attention due to their availability and environmental benefits. This study evaluates the mechanical and durability performance of concrete with WFS and BA, both as standalone and binary combinations. A total of eleven distinct mix designs were prepared and tested, with replacement levels ranging from 0% to 40%. The optimum blend, consisting of 20% WFS and 20% BA, exhibited significant performance enhancements compared to the control mix. Improvements included a 7.8% increase in 28-day compressive strength, a 7.5% rise in split tensile strength, and a 7.7% boost in flexural strength. Durability parameters also improved notably, with an 18.2% reduction in chloride ion permeability, a 14.5% decrease in drying shrinkage, and an 11.2% limitation in acid-induced strength loss. These findings highlight the synergistic effects of WFS and BA in improving concrete quality, to sustainable waste valorization in construction materials.

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ABSTRACT This study explores the potential use of leftover ceramic tiles and coconut shell charcoal as substitutes for fine particles in concrete. Five different mixtures were tested under different water/cement proportions by replacing different amounts of M Sand with waste ceramic tiles and coconut shell charcoal. These mixtures were M1 (100% M), M2 (90% M + 5% T + 5% C), M3 (80% M + 10% T + 10% C), M4 (70% M + 15% T + 15% C), and M5 (60% M + 20% T + 20% C) under different water/cement (0.45, 0.46, 0.47, 0.48, and 0.49). Using an L25 orthogonal array designed with Minitab software, the Taguchi-based grey relational analysis method was used to optimize the mechanical properties of the concrete mix. The results of the experiment showed that adding waste ceramic tiles and coconut shell charcoal enhanced the sustainability of concrete production while lowering reliance on natural resources, and the best mix designs were found. This study shows that recycling waste materials into high-performance concrete is feasible and has the potential to be a sustainable building material. The findings not only address waste management issues but also offer a way forward toward resource-efficient and ecologically friendly concrete production.

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ABSTRACT The quality of industrialized highway base manufacturing critically affects overall highway performance. However, existing base materials often lack sufficient load-bearing capacity and structural stability. This study explores the precipitation behavior and strengthening effects of titanium carbide (TiC) on Ti-6Al-4V titanium alloy and AISI 1020 low carbon steel. TiC-reinforced titanium alloys were prepared via powder metallurgy and hot pressing sintering, while TiC precipitation in low carbon steel was achieved through heat treatment and rapid cooling. Microstructure, hardness, and phase composition were characterized using an electron probe microanalyzer, Vickers hardness tester, and X-ray diffractometer, respectively. Results show that at 650 ℃, the chemical driving force promotes more effective TiC precipitation in both materials, en-hancing their microstructural uniformity and mechanical properties. When applied to highway base structures, TiC-modified samples demonstrated significantly improved hardness and durability. Specifically, sample 11 (with TiC) exhibited a hardness of 2.14 GPa at the eighth test, compared to 1.77 GPa for conventional sample 12. X-ray diffraction patterns revealed intensified peaks at 40°–50°, indicating stronger bonding between the coating and substrate. These findings confirm that TiC precipitation enhances the structural performance of base materials, offering promising potential for advancing highway infrastructure.

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ABSTRACT The use of alkali-activated slag concrete (AASC), which is made from industrial by-product slag, strongly supports sustainable development and provides an environmentally friendly option for construction materials. Fundamental mechanical performance tests were conducted to investigate the impact of replacement ratios of slag and the ratios of basalt fiber (BF) to polypropylene alcohol fiber (PVA) on the physical and mechanical properties of fiber-reinforced AASC. Subsequently, microstructural tests were performed to analyze its microscopic morphological features. The results indicate that the slump value of fiber-reinforced AASC increases with the slag replacement ratio, while it decreases initially and then increases as the fiber replacement ratio increases. With increasing slag replacement ratio and curing ages, the specimen exhibits enhanced compressive strength, input and elastic energy density, whereas the dissipated energy density first increases and then decreases. As the BF content reduces, compressive and splitting tensile strength demonstrate an initial increase followed by a decrease. The microstructural analysis reveals that with increase in slag replacement ratios, the overall compactness of specimen improves. When the total fiber content is 0.2%, the compactness of specimen with equal ratios of BF and PVA is optimal.

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ABSTRACT To overcome the limitations of traditional roller-compacted concrete (RCC) compaction monitoring—which relies on macroscopic experiments, overlooks microscopic mechanisms, and lacks model interpretability—this study proposes a novel framework integrating the discrete element method (DEM) with an improved XGBoost algorithm. The framework incorporates multi-scale features to enable accurate prediction and interpretation of compaction quality. Key innovations include: (1) extracting microscopic parameters such as particle contact numbers, coordination numbers, and pore distributions via DEM simulations, and establishing a quantitative relationship between compaction passes and micro-parameter evolution; (2) introducing a SHAP-based XGBoost interpretability approach that identifies particle contact number as a key driver of compaction degree; and (3) developing a multi-scale feature fusion method to jointly optimize macroscopic and microscopic parameters. Results show that DEM simulations yield compaction degree and porosity errors below 1% and 8%, respectively. The improved XGBoost model achieves an average absolute error of 0.43—outperforming linear regression (1.22) and decision tree (0.91)—with a determination coefficient of 0.97. In practical validation, the prediction error remains within 1%. This research offers a high-precision, interpretable prediction system for RCC compaction, addressing the limitations of empirical methods and enabling real-time optimization of construction parameters.

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ABSTRACT Considering the demand for a more resource efficient, cost effective and eco-friendly construction material, this innovative work aims at exploring the implication of deploying the combination of kenaf fiber and ceramic waste powder as partial river sand replacement on the concrete’s mechanical and durability characteristics. A two-phased experimental work is carried out. Initially, evaluating the impact of ceramic waste powder in varying proportions (20–80%) on the concrete’s mechanical attributes, followed by the impact of kenaf fiber (0–2%) + optimum ceramic waste powder content on the concrete properties. Mechanical Characteristics after underwater immersion of the specimen for 7, 14 and 28 days were analysed, revealing that a 20% ceramic waste powder substitution led to a 9.2% increase in compressive strength, a 19.1% increase in flexural strength, and a 2.7% increase in split tensile strength at 28 days. Phase two assessed kenaf fiber (0–2%) inclusion alongside 20% ceramic waste powder. A 1% fiber addition resulted in a 35.7% rise in flexural strength and an 18% increase in split tensile strength, although compressive strength slightly declined. Durability was evaluated using acid attack and rapid chloride penetration tests. The 20% ceramic waste powder + 0.5% kenaf fiber mix showed reduced strength and weight loss under acid attack and exhibited low chloride permeability. The investigation proved that at optimal combination level the deployment of ceramic waste powder and kenaf fiber in concrete has the capability to produce better durability and mechanical qualities while fostering sustainability through waste reduction and the use of natural fibre. Further, without compromising the structural performance, this investigation advances the creation of ecologically friendly building materials.

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ABSTRACT Chemically modified bentonite has greatly improved its performance due to its structural adjustability. In this study, the modification of bentonite was accomplished through the method of sodium intercalation adsorption. The temperature-sensitive modified bentonite was prepared by initially sodifying bentonite with sodium carbonate and sodium pyrophosphate, intercalating CMC into the interlayer structure of sodified bentonite, and adsorbing N-isopropyl acrylamide (NIPAM) on the surface of bentonite. Further, the deep-water bentonite drilling fluid system was prepared. The optimal sodification conditions were determined by the single-factor control variable method of expansion volume as a drug-bentonite ratio of sodium carbonate of 1:9 and an addition amount of sodium pyrophosphate of 0.5%. The ratio of sodified bentonite to CMC drug-bentonite is 30:1. The addition amount of NIPAM was determined to be 0.5 g through the orthogonal experiment method of two factors of temperature and viscosity. Meanwhile, the temperature-sensitive modification mechanism and performance changes were analyzed through microscopic characterization and performance testing. The results show that the modified bentonite can play a significant temperature regulation role within the temperature range of 60°C and above, and the prepared drilling fluid system has good rheological properties under the condition of temperature change.

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ABSTRACT The study focuses on the potential use of Polyethylene Terephthalate (PET) plastic waste as a substitute for cement replacement for binding properties in paver blocks. This study will be helpful in getting rid of plastic pollution and can be applied to construction industry including water logged areas, pedestrian tracks, kerb stones and light traffic applications. Physical properties, mechanical properties, chemical composition of PET plastic including microstructural properties and statistical analysis are the main focus in this research study. Results of mechanical testing show that by adding more coarse aggregates than PET plastic reduces the compressive strength but increases the tensile strength by keeping the sand content less. The mix ratio incorporating 36% PET plastic, 28% sand and 36% crush gives the optimum results in terms of compressive strength i.e., 43 MPa and also shows good split tensile strength of 6.45 MPa. These blocks also exhibit less water absorption and are temperature resistant up to 100 oC. Regression analysis shows the validity of the experimental results, and SEM images show the significant improvement in the microstructure properties. The analysis of cost revealed the enhancement of economic feasibility and are up to 57% economical as compared to conventional cement-based pavers. Based on the findings of this research study, it is concluded that PET plastic waste can be utilized as a replacement of cement to overcome plastic pollution, to promote sustainable solution to construction industry and contribute towards solid waste management.

Abstract in Portuguese:

RESUMO Os concretos refratários ligados por fosfato são materiais que apresentam reduzido tempo de endurecimento e excelentes propriedades termomecânicas, sendo frequentemente utilizados no reparo de fornos e outras estruturas expostas a altas temperaturas. Este trabalho teve como objetivo o desenvolvimento de concretos quimicamente ligados por fosfato e a avaliação do efeito da adição de agentes antimolhantes a estas composições, visando a aplicação destes materiais em fornos de fusão e espera da indústria de produção de alumínio. O sistema ligante utilizado consistia em uma solução comercial de monofosfato de alumínio [Al(H3PO4)3] e sínter de MgO, e os parâmetros avaliados incluíram a quantidade de solução líquida, bem como o tipo (BaSO4 e/ou CaF2) e a quantidade de agentes antimolhantes (1 ou 2%-p). Para isso, foram efetuados ensaios de resistência mecânica, porosidade aparente, difração de raios X, termogravimetria, resistência ao choque térmica e à corrosão dos concretos produzidos. Todas as composições estudadas apresentaram a formação da fase Mg3(PO4)2 após a etapa de cura, a qual é resultante da reação do fosfato com o MgO. A presença dos agentes antimolhantes contribuiu para o aumento da resistência mecânica à flexão dos concretos estudados, sendo verificado também a redução da porosidade aparente das amostras quando utilizado o CaF2. Baseado nos resultados de resistência ao dano por choque térmico e ao ataque químico, confirmou-se que a combinação do sistema ligante utilizado com o aditivo sulfato de bário resultou em um refratário promissor e com potencial para aplicação em fornos de fusão e espera da indústria do alumínio.

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ABSTRACT Phosphate-bonded refractory castables are materials that exhibit reduced setting time and excellent thermomechanical properties, being frequently used in the repair of furnaces and other structures exposed to high temperatures. This work aimed to develop chemically phosphate-bonded castables and evaluate the effect of adding anti-wetting to these compositions, targeting the application of such materials in melting and holding furnaces in the aluminum production industry. The binder system used consisted of a commercial aluminum monophosphate [Al(H3PO4)3] solution and MgO sinter, and the evaluated parameters included the amount of liquid solution, as well as the type (BaSO4 and/or CaF2) and the amount of anti-wetting agents (1 or 2 wt.%). For this purpose, mechanical strength, apparent porosity, X-ray diffraction, thermogravimetry, thermal shock resistance, and corrosion resistance tests of the produced castables were conducted. All compositions presented the formation of the Mg3(PO4)2 phase after the curing stage, which results from the reaction of phosphate with MgO. The presence of anti-wetting agents contributed to the increase in the flexural strength of the studied castables, with a reduction in the apparent porosity of the samples when CaF2 was used. Based on the results of thermal shock and corrosion resistance, it was confirmed that the combination of the binder system used with the barium sulfate additive resulted in a promising refractory with potential for application in melting and holding furnaces in the aluminum industry.

Abstract in Portuguese:

RESUMO A norma DNER-PRO 277/97 descreve o método de controle estatístico de qualidade de obras e serviços rodoviários no Brasil e pressupõe a distribuição normal das características executivas. Entretanto, a literatura documenta a violação frequente dessa hipótese. Diante disso, este trabalho investigou a influência da não normalidade sobre as decisões de aceitação/rejeição de acordo com a norma supracitada. As informações de teor de ligante asfáltico referente à execução de três obras rodoviárias foram tomadas como referência. Utilizando diferentes testes estatísticos (Shapiro-Wilk, Kolmogorov-Smirnov e Anderson-Darling), ratificou-se a possibilidade de desvios de normalidade, onde a distribuição de probabilidade log-logística mostrou maior aderência aos dados. Para esse caso em particular, uma simulação de Monte Carlo apontou a existência de um viés de rejeição severo para pequenas amostras ao adotar-se a hipótese de normalidade dos dados. Desse modo, em casos em que a não normalidade não pode ser desprezada, o risco do executante pode ser superior ao previsto em norma.

Abstract in English:

ABSTRACT The DNER-PRO 277/97 standard describes the method of statistical quality control for road works and services in Brazil, assuming a normal distribution of executive characteristics. However, the literature regularly documents the violation of this assumption. In this context, this study investigated the influence of non-normality on the acceptance/rejection decisions according to the aforementioned standard. Information on asphalt binder content from the execution of three projects was used as a reference. Using different statistical tests (Shapiro-Wilk, Kolmogorov-Smirnov and Anderson-Darling), the possibility of deviations from normality was confirmed, with the log-logistic probability distribution showing greater fit to the data. For this particular case, a Monte Carlo simulation pointed out a severe rejection bias for small samples when adopting the assumption of data normality. Therefore, in cases where non-normality cannot be disregarded, the risk for the executor may be higher than stated in the standard.

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ABSTRACT This study conducts a comprehensive investigation into the effect of isothermal aging on the microstructural evolution and mechanical properties of a Mg-8.2Gd-0.5Zr (wt.%) alloy. The alloy was subjected to solution treatment followed by aging at three distinct temperatures: 200 °C, 225 °C, and 250 °C for durations up to 300 hours. The age-hardening response was characterized by Vickers microhardness measurements, revealing a strong dependence on temperature, with the highest peak hardness of 135 HV achieved at 200 °C after 96 hours. Detailed microstructural analysis using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) established the precipitation sequence as Supersaturated Solid Solution (SSSS) → β″ (D019) → β′ (bco) → β (FCC). The peak-aged condition was associated with a high number density of fine, lenticular βʹ precipitates on the prismatic planes of the α-Mg matrix. Tensile testing demonstrated that the peak-aged alloy exhibited a remarkable increase in strength, with a yield strength of 290 MPa and an ultimate tensile strength of 380 MPa, albeit with a significant reduction in ductility. Fracture surface analysis revealed a transition from ductile dimple fracture in the solution-treated state to brittle cleavage fracture in the peak-aged condition. A quantitative analysis of strengthening mechanisms confirms that precipitation hardening via the Orowan mechanism is the dominant contributor to the alloy’s strength, accounting for approximately 75% of the increase in yield strength (≈70–80% when input uncertainties are considered). These findings provide a systematic understanding of the structure-property relationships in Mg-Gd-Zr alloys, offering a basis for optimizing heat treatments to achieve desired mechanical performance.

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Visual Abstract GRAPHICAL ABSTRACT

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ABSTRACT Forest biomass can be used for heat and electricity generation; meeting energy demands on multiple scales. In urban areas, tree pruning is a significant yet often underutilized source of this biomass. Therefore, this work aimed to characterize the biomass from urban pruning for heat production, evaluating the physical and chemical parameters of the biomass in natura. For this, the pruning biomass was collected from the Urban Cleaning Company of the City of Recife (EMLURB/PCR), and five different areas were sampled, called Political-Administrative Regions (PARs). The physicochemical properties (moisture content, bulk density, and heating value) and the structural, elementary, and immediate chemical composition of the in natura biomass were analyzed. As for physical properties, pruning biomass has a high moisture content, requiring prior drying to generate energy, and sufficient heat value to produce heat energy. In addition, pruning biomass has a high ash content, which can compromise the durability of the kilns for energy conversion. As for structural chemistry, it presents high levels of holocellulose and normal levels of extractives and lignin. Therefore, depending on the proper management of pruning stubble, they have the potential to generate heat energy, at a rate of approximately 2.8 Tcal per year.

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ABSTRACT This study investigates the stress corrosion cracking (SCC) behavior of Nb–Ti microalloyed API 5L X70 high- strength low-alloy (HSLA) steel—widely deployed in marine flexible risers and subsea pipelines—under a simulated acidic sour marine environment (pH 3, 3.5 wt.% NaCl, H₂S saturation). While prior research has examined hydrogen embrittlement (HE) or anodic dissolution (AD) individually in high-strength steels, this work uniquely integrates slow strain rate tensile (SSRT) testing with in-situ potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and high-resolution fractography to concurrently assess mechanical degradation, electrochemical behavior, and fracture morphology. The results demonstrate pronounced SCC susceptibility, with a substantial reduction in ductility and time to failure in the corrosive environment compared to air. Electrochemical data revealed high corrosion rates, active dissolution, and a low-frequency inductive loop characteristic of hydrogen-related interfacial processes. Fractography confirmed predominantly brittle fracture modes, including quasi-cleavage and transgranular cracking, which directly correlate with the electrochemical signatures. This concurrent analysis provides new mechanistic insight into the synergistic operation of HE—strongly promoted by low pH and H₂S—and AD in Nb–Ti microalloyed steels, offering critical guidance for material selection and SCC mitigation strategies in aggressive marine service.

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ABSTRACT This research presents an experimental and analytical investigation of an interior precast beam-column connection using a hybrid steel connector. The beam-column connections were introduced with different positive and negative reinforcement alignments to achieve behaviour comparable to a monolithic reinforced concrete connection. The primary objective of this study is to examine key parameters such as load-carrying capacity, mode of failure, crack pattern, ductility, stiffness, and energy dissipation capacity in beam-column connections. Three half-scale beam-column connection specimens were tested under displacement-controlled lateral cyclic loading combined with constant axial loading. One cast-in-place control specimen and two precast specimens were tested. The control specimen was designed based on the strong-column–weak-beam concept to meet code requirements for strength, while the precast specimens were detailed to replicate this design approach. To enhance performance, the precast specimens (PBC1 and PBC2) were fabricated with different configurations, including variations in reinforcement alignment and using hybrid steel connectors of varying sizes. Considering the test variables, the above-mentioned key parameters for the control specimen were compared with those of the precast specimens (PBC1 and PBC2). The results showed that the precast specimens demonstrated enhanced strength and energy dissipation compared to the monolithic specimen, based on single-specimen test results. This clarification addresses the limited statistical representation due to using only one specimen per configuration. Using hybrid steel connectors with asymmetric detailing and varied connector heights represents a novel approach to improving seismic behaviour in interior joints. Seismic performance was further evaluated using damage indices and validated through Finite Element Analysis (FEA) using ABAQUS software. The FEA results closely correlated with the experimental results. Additionally, the analytical results help to predict the experimental results at the peak point.

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ABSTRACT This study systematically analyzed the microstructure, quality, and corrosion resistance of arc-sprayed Zn, Al, and Zn15Al coatings commonly used on structural components in port equipment. The arc-sprayed Zn and Zn15Al coatings exhibited a lamellar structure, where the Zn coating consisted of a single Zn-rich phase while the Zn15Al coating comprised a Zn-Al eutectic. In contrast, the arc-sprayed Al coating displayed a relatively dense internal morphology without distinct lamellar features. The Al coating exhibited the highest bond strength at 10.22 MPa, significantly exceeding those of the Zn (7.51 MPa) and Zn15Al (7.35 MPa) coatings. The Al coating had the strongest corrosion resistance with a self-corrosion current density of 1.622 × 10−6 A·cm−2. With prolonged immersion time, the corrosion products on the Al coating surface evolved from an intermittent to a continuous distribution pattern, identified as Al(OH)3. Conversely, the Zn and Zn15Al coatings exhibited flocculent and granular corrosion products, characterized as Zn5(OH)8Cl2·H2O and Zn6Al2(OH)16CO3·4H2O, respectively. These findings offer valuable reference data for corrosion protection of structural components in port equipment.

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ABSTRACT To prevent rapid degradation causing plugging failure in degradable magnesium alloy packer slips under high-temperature, high-pressure, corrosive conditions, a composite dual-coated magnesium alloy was developed. The coating (hereafter referred to as Black Composite Coating, BCC) utilized micro-arc oxidation (MAO) and spray coating. SEM, XRD, FTIR, polarization curves, and EIS characterized microstructure and corrosion performance pre- and post-modification. Results showed the MAO-treated surface formed a porous structure, increasing specific surface area and roughness. This enhanced base/auxiliary material adhesion and corrosion resistance. The added black composite coating significantly reduced corrosion current density and increased charge transfer resistance (Rct). MAO pores provided mechanical interlocking sites. The black coating's low porosity and sealing blocked corrosive media penetration. Compared to soluble magnesium alloys, the coating reduced corrosion current density by ~five orders of magnitude (from ~10−4 to ~10−9 A/cm2) and increased Rct by ~six orders (from ~102 to ~106 Ω·cm2). Corrosion rates were suppressed >91.8%, stabilizing between 0.1~1.0 mm/year. Per ISO 9223:2012, this moderate corrosion resistance (Class C3-C4) indicates suitability for mildly aggressive environments like indoor industrial areas, low-chloride rural zones, or oil wells. This technique enhances degradable magnesium alloy corrosion resistance downhole, providing valuable industrial guidance.

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ABSTRACT This study investigated the improved surface properties of a hybrid material containing silicon nitride (Si3N4) and boron nitride (BN) nanoparticles introduced via a three-stage friction stir processing (FSP) method. Unlike the traditional blind hole powder addition method, which results in particle aggregation, the longitudinal groove method achieves a more uniform distribution of reinforcements. Three Si3N4:BN mixture ratios (70:30, 60:40, and 50:50) were prepared, and their effects on microstructural changes, mechanical response, and tribological properties were systematically analyzed. Compared to the untreated alloy, the 60:40 composition provided the most balanced properties, with a 42% increase in microhardness (121.1 HV), a 58% reduction in wear rate (1.99 × 10−4mm3/N4m), and a low coefficient of friction of 0.29. The 70:30 formulation exhibited the highest tensile strength (131.96 MPa), an 18% increase. Microstructural observations confirmed the formation of refined equiaxed grains (approximately 5.2 μm) and uniformly dispersed nanoparticles due to dynamic recrystallization and Zener pinning. Phase analysis using X-ray diffraction (XRD) and EDS confirmed stable α-Al, Si3N4, and h-BN phases, with no intermetallic compounds. These results demonstrate that multi-pass FSP with hybrid ceramic reinforcement can effectively improve the surface integrity of aluminum alloys and lay the foundation for future research into corrosion resistance, high-temperature stability, and fatigue performance in aerospace, marine, and automotive applications.

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ABSTRACT To improve the interfacial bonding properties of carbon fiber-reinforced polymer (CFRP) composites, this study proposes an effective surface modification strategy for carbon fibers. A CF-KH560-PGO hybrid reinforcement was fabricated through chemical grafting, employing γ-glycidoxypropyltrimethoxysilane (KH560) as a coupling agent to bridge the carbon fibers (CF) with polyethyleneimine (PEI)-functionalized graphene oxide (GO). The presence of lamellar PGO has been observed on the surface of modified carbon fibers. The presence of the –NH2 peak, in conjunction with the C–N peak, on the surface of the carbon fibers, served to verify the grafting of PGO. The synergistic effect of PGO and KH560 significantly enhanced the surface wettability of carbon fibers. This study systematically investigates the mechanical performance of composites fabricated through different CF modification approaches, along with the underlying interfacial reinforcement mechanisms. The modified carbon fiber composites exhibited remarkable tensile strength (669.7 MPa) and interlaminar shear strength (60.41 MPa), representing 49.89% and 20.36% improvements respectively over desized carbon fiber composites. Grafted PGO can provide abundant amino groups for chemical bonding with epoxy resins. That KH560 and PGO increased the thickness of the interfacial transition layer, thereby enhancing the load transfer at the composite interface.

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ABSTRACT A novel study on fibre-reinforced cement less geopolymer concrete with diverse molar concentrations has gained attention in recent years. The current study uniquely explores the combined influence of four distinct molar concentrations (6M, 8M, 10M, and 12M) and five fibre volume fractions (0%, 0.25%, 0.50%, 0.75%, and 1%) on the mechanical behaviour of GPC. An experimental investigation on 20 numbers of varied geopolymer concrete mixes was performed, and the mechanical properties were evaluated and reported. Also, A non-destructive test using ultrasonic pulse velocity was made, and the regression analysis with compressive strength is reported. The result indicates that 10M concentration provides the optimum results than other molar concentrations, with 0.75% as the optimum basalt fibre volume addition to the cementless geopolymer concrete. The basalt fibre addition improves the split tensile strength and flexural bending strengths considerably. Morphology studies indicate that the lower molar concentration gives a comparatively loose and voided concrete matrix with a loose packing of ingredients than the higher molar concentration. This research provides a comprehensive and optimised approach by simultaneous variation of Molar concentration and fibre volume to enhance geopolymer concrete, supported by both mechanical investigation and microstructural analysis.

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Abstract Bio-based polyurethanes (PUs) offer a route to reduce fossil-derived plastics. Here, we synthesize castor oil-based PU films via a two-step prepolymer method and systematically vary the NCO/OH ratio (1.0–1.5) and isocyanate structure (aromatic MDI vs. aliphatic HMDI) to elucidate structure–property–biodegradability relationships. Thermal/mechanical behavior (TGA/DSC; tensile testing; hardness), morphology (AFM/SEM), surface wetting, and end-of-life performance (soil burial, 180 d; lipase assay, 28 d) were evaluated. Increasing NCO/OH from 1.0 to 1.5 raised tensile strength from 5.5 to 18.2 MPa and Tonset from 291 to 316 °C, while reducing elongation at break from 352% to 88%. At fixed NCO/OH = 1.2, HMDI-based PU was more extensible (455% vs. 218%), more hydrophilic, and showed greater mass loss than the MDI analog in both soil (35.5% vs. 18.1%) and enzymatic tests (22.1% vs. 9.5%). These data demonstrate that hard-segment content and isocyanate chemistry can be used to tune thermomechanical performance and biodegradation rate in castor-oil PUs, informing sustainable materials design.

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ABSTRACT For granite materials with complex microstructure, the mechanism of subsurface crack damage and initiation and propagation in abrasive processing may not follow the classical indentation fracture mechanics theory. Consequently, research on crack initiation and propagation is centered on the microstructure of granite. The simulation model of cutting granite at grain boundary scale was established, and the mechanical response, stress field distribution, and microcrack initiation and propagation mechanism under different process parameters were studied. The results showed that the material positioned in front of the diamond grains is predominantly subjected to shear load, while the material situated below the diamond grains is primarily subjected to tensile load. Crystal boundaries have been shown to have a significant effect on crack initiation and propagation. The mechanism of crystal boundary crack systems involves dislocation accumulation at the crystal boundaries. As cutting progresses, subsurface cracks in granite undergo several processes, including dislocation excitation, dislocation movement, crystal boundary accumulation, microcrack propagation at the crystal boundaries, macro crack formation, and transgranular fracture. The number of subsurface microcracks increases with the increase in strain rate. In addition, the penetration of the intermediate crack and the internal micro-crack leads to the deviation of the intermediate crack angle.

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ABSTRACT Laser additive connection is one of the main methods for additive manufacture of large-scale titanium alloy components. However, the connection deformation will seriously reduce the dimensional accuracy of large-scale components. By applying the methods of the finite-element simulation and the experiment, we analyzed the influence of different scanning strategies on the temperature field, stress and deformation of the connection components in this manuscript to effectively control the deformation of the laser additive connection metal component. The research results provide the basis for the laser additive connection scanning strategy selection. Then, based on the determined scanning strategy, the influence of different line energy density and connection area size on the laser additive connection angular deformation is further studied. Considering the influence of multiple parameters, a rapid prediction model for the angular deformation of laser additive connection was established, and the model error was less than 6%. The angular deformation of the laser additive connection is reduced by 80% by pre-deformation compensation. The deformation of the laser additive connection is effectively controlled.

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ABSTRACT This study examines the influence of incorporating Municipal Solid Waste Incineration Ash (MSWIA), nano Municipal Solid Waste Incineration Ash (nMSWIA), Rice Husk Ash (RHA), and nano Rice Husk Ash (nRHA), both with and without basalt fibre, on the development of High Strength Reinforced Concrete Beams (HSRCB). The research explored the mix proportions for ash replacement levels of 5%, 10%, 15%, 20%, 25%, and 30% for each type of ash, alongside the impact of adding 0.5% basalt fibre. A Scanning Electron Microscope (SEM) analysis was conducted to understand the material properties of the incorporated ashes. The mechanical properties of the concrete mixes were evaluated, and beams were made using the optimum mixes from the four ash proportions to investigate load capacity, deflection, ductility, and stiffness. A mathematical analysis was performed to calculate beam deflection and compare it with the experimentally obtained values. The failure mode observed during testing was analyzed to understand the behaviour of the HSRCB under load. The results reveal that the NRB4 mix, containing a specific combination of ash type, replacement level, and the presence of basalt fibre, exhibits optimal performance. NRB4 demonstrates superior load capacity, improved deflection control, enhanced ductility, and greater stiffness than other investigated mixes. This research highlights the potential of utilizing waste materials like MSWIA, nMSWIA, RHA, and nRHA in HSRCB production, promoting sustainable construction practices. Including basalt fibre further refines the mechanical properties, making NRB4 a promising mix for HSRCB applications.

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ABSTRACT The demand for durable concrete in bridge engineering has driven interest in reactive powder concrete (RPC). However, its long-term resistance to sulfate attack remains a concern. This study innovatively enhances RPC’s mechanical and corrosion resistance by optimizing the incorporation of 0.12 wt% multi-walled carbon nanotubes (MWCNTs) through a physico-chemical dispersion method (polyvinylpyrrolidone (PVP)-assisted ultrasonication), confirmed to be highly effective. The optimized dispersion achieved a stable Zeta potential of −38.7 ± 1.4 mV after 168 hours. Dry-wet cycling in 12% Na2SO4 and MgSO4 simulated sulfate exposure. Key findings show that MWCNT-modified RPC exhibited a 32.98% increase in compressive strength (125.03 MPa) and a 28.19% increase in flexural strength. X-ray computed tomography (X-ray CT) and scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM-EDS) analyses quantitatively confirm MWCNT- induced pore refinement (51.9% reduction in pore number, 13.55% decrease in porosity) and micro-crack bridging. After 150 Na2SO4 cycles, the dynamic elastic modulus loss was 2.13%, while 120 MgSO4 cycles resulted in a 3.25% loss, with mass loss rates below 1%. These findings demonstrate that 0.12 wt% MWCNTs, via the optimized dispersion method, significantly enhance RPC’s compactness, crack resistance, and sulfate durability, providing critical technical support for extending the service life of bridge infrastructure in aggressive sulfate environments.

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ABSTRACT The present study investigates the effect of heat treatment on the microstructure, mechanical, and wear characteristics of the Ti-6Al-5Zr-0.5Mo-0.2Si alloy. Solution heat treatment combined with aging near the β-transus temperature substantially modified the microstructure, resulting in notable enhancements in the mechanical properties. Solution annealing followed by ageing at 1050°C was highly effective, as it formed secondary α phases near the retained β phase. This refined microstructure contributed to a notable increase in tensile strength, achieving a higher strength of 1270 ± 10 MPa (29% more) and a microhardness of 360 ± 5 HV (14% more) than the as-received base material through transformation strengthening mechanisms. Additionally, the heat-treated alloys demonstrated superior wear resistance compared to their as-received condition. High-temperature wear testing at 200 °C showed the formation of a stable tribo-oxide layer on the alloy surface, which acted as a protective barrier against direct metal-to-metal contact. This layer significantly enhanced wear resistance, reaching 4.39 × 10−3 mm3/Nm, an improvement of 33% over the as-received base metal.

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ABSTRACT The growing demand for sustainable building materials has sparked renewed interest in blocks for construction, particularly when stabilized with natural fibers to enhance their mechanical properties. This study presents a systematic review conducted in the ScienceDirect and Scopus databases, covering publications from 2015 to 2025. The inclusion criteria considered experimental studies that analyzed adobe stabilized with plant fibers and reported their mechanical properties. A total of nine studies met the eligibility criteria. The fibers evaluated included straw, Hibiscus cannabinus, palm, neem, jute, seagrass, date palm, and pine needles. Overall, the addition of fibers improved mechanical performance. The best compressive strength result was obtained with neem fibers, showing a 35% increase compared to the reference block. For tensile strength, the most significant improvement was observed with palm fibers, resulting in a 19% increase compared to the control. These results confirm that controlled fiber incorporation improves adobe performance, particularly in terms of compressive and tensile strength, while maintaining its sustainable and low-cost characteristics. However, differences in soil types and experimental procedures between studies limit comparability, highlighting the need for standardized methodologies in future research.

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ABSTRACT Direct determination of vanadium (V) in graphite by mixed-acid digestion and inductively coupled plasma mass spectrometry (ICP-MS) is hindered by matrix effects and polyatomic interferences, resulting in limited trueness. Conventional methods for geological materials often have high detection limits (LODs) and low throughput. This study presents a high-temperature ashing pretreatment combined with mixed-acid digestion and ICP-MS for the true and precise quantification of V in graphite. Key parameters, including ashing temperature, sample mass, and digestion protocol, were optimized. Ashing at 950 °C efficiently removed the carbon matrix and minimized analyte loss, particularly in high-carbon samples. Polyatomic interference from 35Cl16O+ on the 51V+ signal was effectively eliminated using the kinetic energy discrimination (KED) mode. The method achieved an LOD of 0.62 μg/g, a limit of quantitation (LOQ) of 2.48 μg/g, and excellent linearity (R2 = 0.9994) over 0–1,000 μg/L. Spike recoveries ranged from 94% to 103.5%, with relative standard deviations (RSDs) below 3.8%. Compared with direct acid digestion, the proposed approach significantly improves trueness, precision, and robustness, offering a reliable, high-throughput solution for V analysis in graphite. This protocol provides an effective analytical tool for geological exploration and resource assessment.

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ABSTRACT This research paper presents an improved Battery and Energy Management System (BEMS) designed for Brushless DC (BLDC) motor-driven electric vehicles using smart control approaches and machine learning. By including predictive ML models such as Decision Trees, Support Vector Machines (SVM), and XGBoost for precise assessment of battery state-of-charge (SOC) and real-time energy allocation, the system seeks to optimise motor control and battery performance. Dynamically controlling power flow depending on SOC, temperature, and driving circumstances, a smart battery and energy management system is created. Comparison with traditional EMS methods reveals notable gains in energy economy, temperature management, battery life, and motor response. The combination of ML and smart control shows a strong and flexible system for improving the general performance and sustainability of electric vehicle powertrains.

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ABSTRACT Highways are essential components of transportation infrastructure, and their performance depends critically on the mechanical behavior of multilayered pavement systems. This study investigates stress distribution in layered highway structures under circular loading using the Finite Element Method (FEM). A multilayered model including asphalt, base, subbase, and subgrade soil layers was developed, and vertical stress increments were evaluated for each layer. Results show that rigid upper layers, such as asphalt and base, concentrate stresses near the surface, while softer subbase and subgrade layers distribute stresses over a wider area. FEM results were quantitatively compared with analytical solutions based on Boussinesq theory, revealing a maximum deviation of approximately 7% in stress predictions, confirming the model’s accuracy. The study demonstrates that FEM-based simulations provide detailed insights into load transfer mechanisms and layer interactions, supporting optimized pavement design and reduced maintenance requirements.

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ABSTRACT Nowadays, corrosion severely affects concrete due to various factors, such as exposure to chlorides, carbonation, moisture penetration, cracking and chemical exposure. Many researchers have investigated ways to prevent this issue using different parameters. The present study examined the mechanical properties of concrete by adding various types of cement (OPC, PPC and PSC), zeolite, and corrosion inhibitors. Zeolite partially replaced the cement at various percentages (10%, 20% and 30%). Additionally, the corrosion inhibitor (2% for OPC and 2.5% for PPC and PSC) is incorporated into the concrete mix. A total of 24 concrete mixes are examined for their mechanical properties. These properties, such as Compressive Strength (CS), Split Tensile Strength (STS), and Flexural Strength (FS), were investigated using respective specimens. The main objectives of this study were to experimentally investigate the mechanical properties of the concrete and predict these mechanical properties using linear regression analysis and various codes. According to the experimental study, the optimum zeolite content of 20% provided superior performance compared to the other mix proportions. The mechanical properties improved with the optimum zeolite content of 20% in the concrete mix. Compared to conventional concrete, the mechanical properties were enhanced for compressive strength by 4.92%, 3.06%, and 7.87%; split tensile strength by 6.08%, 3.57%, and 8.24%; and flexural strength by 5.06%, 3.17%, and 6.57%, respectively. The incorporation of the inhibitor into the concrete mixture had also led to an improvement in the mechanical properties of the concrete. Specifically, the enhancements observed were 4.75%, 3.42%, and 7.93% for compressive strength; 5.49%, 6.49%, and 8.77% for split tensile strength; and 4.99%, 4.30%, and 7.17% for flexural strength, respectively. The mechanical properties are predicted using linear regression analysis and various codes. The relationship between CS & STS and CS & FS regression analysis was studied, and the comparison of both coefficients of variation is found to be 0.91% and 0.41%, respectively. The regression equations, IS: 456-2000 and ACI 318-08 codes, correlated better than those from other codes. Furthermore, the partial replacement of the zeolite by cement is recommended for practical application.

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ABSTRACT In austenitic-ferritic or duplex stainless steels, the microstructure is basically determined by the chromium and nickel contents, which are ferritic or austenitic phases stabilizers. Currently, duplex stainless steels are used to replace austenitic stainless steels in industrial applications, where requirements for corrosion resistance and mechanical strength are greater. In these steels, solidification starts at about 1450 oC with the formation of ferrite (α), which gives origin to austenite (γ) near 1300 oC. The σ phase nucleates preferentially in austenite/ferrite interface incoherent with the matrix in the range of 600 to 950 oC and compromises the cast steels toughness. Laves phase (Fe2Nb) is favored in stainless steels containing niobium. In this context, the objective of this research was to evaluate the effect of niobium on the formation of sigma and Laves phase in conventional austenitic-ferritic stainless steel and modified with 0.2, 0.5 and 1.5% niobium. The steels were heated at 1050 ºC for one hour and subsequently at 650 °C too, with cooling in water. The chemical compositions of sigma and Laves were determined semi-quantitative by energy dispersive X-rays (EDS). The amounts of Laves and sigma were obtained by computational thermodynamic simulation with the FactSage software. The results show that the thermodynamic simulation predicts Laves in the four steels, although in conventional stainless steel the microstructure is free from this phase. Regarding microstructural analyses by SEM, it is possible to observe the sigma phase in all steels, only after aging, while Laves appears in those modified with niobium in both heat treatment conditions. Whit regard to niobium, it favors the formation of sigma and Laves phase, however, the thermodynamic simulation results are different from the experimental ones.

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ABSTRACT This study aims to propose a novel infill wall system for RC moment-resisting frames, using 250 mm thick AAC blocks and polyurethane binders. Numerical validation with Abaqus and SAP2000 in single-story frames showed strong agreement with previous experimental and numerical studies. In single-story frames, the proposed AAC block infills with polyurethane binder increased the lateral load capacity by approximately 23% after yielding, compared to frames with traditional hollow brick infills. This value also indicates a 70% increase relative to the bare frame. In the pushover analysis of three-story models, the proposed system approximately increased lateral load capacity by 38% when compared with the structure without any infill, whereas a traditional hollow brick wall only increased capacity by 12%. The proposed wall significantly increased energy consumption and reduced plastic hinge damage when compared with bare and traditionally infilled frames. Stress analysis indicated potential infill cracking at maximum drift. Overall, the system demonstrates promising potential for enhancing seismic performance in RC structures.

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ABSTRACT This paper introduces a sophisticated dual energy storage system (DESS) designed to enhance the efficiency and performance of electric vehicles. The system strategically combines a primary photovoltaic (PV) energy source with secondary battery and supercapacitor storage. Leveraging the rapid charge-discharge capabilities and high-power density of supercapacitors alongside the high energy density of batteries, the DESS aims to optimize power delivery by effectively balancing long-term energy storage with instantaneous power demands, particularly for regenerative braking and rapid acceleration. The operational strategy involves the supercapacitor handling high-frequency current fluctuations and the battery addressing low-frequency components, resulting in a smoother voltage profile compared to conventional systems. Optimal sizing and integration of these components are determined based on specific load requirements, voltage levels, energy capacity, and cycling life. The DESS, integrated with a permanent magnet synchronous motor (PMSM) in the d and q axes, undergoes rigorous testing under diverse real-world conditions, including varying wind and terrain, with and without braking. Simulations using MATLAB and DSPACE hardware 1KW PMSM to validate the system's current profile, voltage regulation, power split operation in different load conditions, and overall energy efficiency, demonstrating a significant improvement in the reliability, performance, and efficiency of electric vehicles. The proposed system achieves a DC-link voltage regulation of 48 V, improves energy efficiency by 12%, and extends battery lifetime by reducing stress currents by 18%.

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ABSTRACT This research examines the self-healing ability and durability of self-compacting concrete (SCC) enhanced by microbial calcium carbonate precipitation using Bacillus megaterium (BM). To stimulate bacterial activity, Fly Ash (FA) and Alccofine (AF) were used as partial replacements for Ordinary Portland Cement (OPC) at 5%, 10%, 15%, and 20% by weight. Twelve SCC mixes were prepared to assess the combined effects of BM and mineral admixtures on mechanical and durability properties. The AF10FA10 mix, containing 10% AF and 10% FA, showed the best performance with a 28-day compressive strength of 46 MPa, a 19% increase over the control (AF0FA0). Flexural and split tensile strengths improved by 18% and 17%, respectively. Bacterial precipitation of calcium carbonate sealed micro-cracks, reducing water absorption and porosity by 15% and 32%. Acid attack resistance confirmed higher compressive strength retention after 28 days in H2SO4. XRD, FTIR, and TGA analyses revealed calcite formation and greater calcium silicate hydrate (C–S–H) gel content, indicating a denser matrix. Although a full life cycle assessment was not performed, cement reduction suggests lower embodied carbon. This approach offers a sustainable route to stronger, more durable AF-based SCC.

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ABSTRACT Fiber-reinforced concrete (FRC) offers several benefits, including improved tensile strength, greater ductility, enhanced energy absorption, and superior impact resistance. In the present study, experimental investigations were carried out on high-performance fiber-reinforced concrete (HPFRC) containing rice husk ash (RHA), crimped steel fibers, and Nanocellulose fibrils (NCF). The NCFs were added to the concrete mixtures in percentages of 0.4 and 0.6 of the binder composition. The volume of crimped steel fibers was kept constant as 1.5% for better comparison. The laboratory experimental program involved a total of seven mixes with three samples per mix for compressive strength, flexural strength, elastic modulus, scanning electron microscopy. The flexural performance was tested for seven FRC beams. Additionally, finite element method (FEM) based numerical analysis was conducted for further investigation. Ductility parameters, including energy ductility and deflection ductility, were assessed using the load–deflection behavior of the FRC beams. Results from the experimental program indicate that the addition of NCF showed marginal improvement on the early age compressive strength, whereas the 28-day strength improved significantly. At 28 days, the mix containing RHA, 0.4% NCF exhibited the highest compressive strength, approximately 68 MPa, compared to the other mixes. Adding 0.4% NCFs increased the flexural strength up to 40.6% compared to the control mix due to the crack-bridging mechanism. Morphology analysis reveals a dense matrix aggregate interface due to the formation of hydration crystals. The addition of steel fibers and NCFs led to a notable enhancement in ductility performance. The HPFRC beam with RNCSF (1.5:0.4) showed the highest deflection ductility ratio, 58% higher than the control RC beam. Similarly, the peak energy ductility ratio for the same mix showed a 65% increase. The numerical simulation of load–deflection behavior and crack patterns of fiber-reinforced RC beams closely matched the experimental results.

Abstract in Portuguese:

RESUMO A argamassa estabilizada surge no mercado da construção como uma alternativa industrializada para o aumento da produtividade. Contudo, seu desempenho é dependente de aditivos, o que torna pertinente a avaliação do comportamento de adições transpostas da tecnologia do concreto. Nesse contexto, a influência de aditivos cristalizantes, amplamente utilizados para impermeabilização de concretos ainda é incipiente, representando uma lacuna técnica sobre seu real impacto nas propriedades da argamassa. Neste cenário, o presente trabalho investiga a influência da incorporação de dois tipos de aditivos cristalizantes (Tipo 1 e Tipo 2) nas propriedades de argamassas estabilizadas produzidas em usinas. Para tanto, foram avaliados os efeitos dos aditivos em três dosagens (0,35%, 0,70% e 1,00%) em relação à massa de cimento. Foram ensaiadas sete amostras, sendo uma de referência e seis com as adições, submetidas a ensaios no estado fresco (consistência, teor de ar) e endurecido (aderência, compressão e flexão). Os resultados indicam que, embora os aditivos cristalizantes melhorem a manutenção da trabalhabilidade ao longo do tempo de uso, seu impacto no estado endurecido é crítico. Verificou-se que determinadas dosagens não atingiram o requisito mínimo de resistência de aderência à tração, demonstrando que a adição destes componentes pode comprometer o desempenho mecânico da argamassa.

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ABSTRACT Stabilized mortar has emerged in the construction market as an industrialized alternative for increasing productivity. However, its performance is dependent on additives, making it relevant to assess the behavior of admixtures adapted from concrete technology. In this context, the influence of crystallizing additives—widely used for waterproofing concrete—is still incipient, representing a technical gap regarding their actual impact on mortar properties. In this scenario, this study investigates the influence of incorporating two types of crystallizing additives (Type 1 and Type 2) on the properties of stabilized mortars produced in plants. For this purpose, the effects of the additives were evaluated at three dosages (0.35%, 0.70%, and 1.00%) relative to the cement mass. Seven samples were tested: one reference and six with the admixtures, subjected to tests in the fresh state (consistency, air content) and hardened state (bond strength, compression, and flexural strength). The results indicate that although the crystallizing additives improve workability retention over the period of use, their impact in the hardened state is critical. It was found that certain dosages did not meet the minimum requirement for tensile bond strength, demonstrating that the addition of these components can compromise the mechanical performance of the mortar.

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ABSTRACT The increasing demand for sustainable and high-performance materials in civil engineering highlights the importance of understanding the relationship between wood anatomy and its mechanical behavior. This study aims to evaluate correlations between anatomical parameters and mechanical properties of Cumaru (Dipteryx odorata), with the goal of improving its classification and structural application potential. Microscopy techniques were used to analyze key anatomical features, including fiber length, wall thickness, and vessel diameter, while mechanical tests were performed in accordance with Code NBR 7190-3:2022 to determine strength and stiffness parameters. Statistical analysis was applied to identify significant correlations between anatomical traits and physical-mechanical properties. Results demonstrate that anatomical parameters, together with apparent density, are reliable predictors of mechanical performance, particularly influencing modulus of elasticity and modulus of rupture. These findings confirm that anatomical analysis can complement traditional mechanical testing, enabling more efficient and non-destructive approaches for assessing wood quality. The study provides practical insights for selection, classification, and optimized utilization of Cumaru in engineering and construction, reinforcing its relevance as a sustainable structural material.

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ABSTRACT Herein, industrial-scale extruded profiles of aluminum alloy (AA) 7108 with rectangular cross-sections of dimensions 25.60 mm × 15.95 mm were used to investigate the effect of number of passes and strain rate on their crystallographic texture. After the initial microstructural and textural characterization, the samples were solution-annealed and cold-rolled using different numbers of passes to achieve the same degree of reduction. The samples that were cold-rolled for a few number of passes exhibited a remaining Cube texture component {001} <001> (similar to that observed in the AA 7108 as-received bars), a Goss component {011} <001>, and a Brass component {011} <211>. In contrast, the samples rolled for a high number of passes demonstrated only a strong Goss component {011} <001>.

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ABSTRACT Planar accuracy is a critical geometric precision requirement for components, directly influencing their functional performance. To investigate the relationship between process parameters and planar accuracy in the open Fused Deposition Modeling (FDM) process, and to enhance the shape accuracy of printed models, a series of experiments, including Plackett-Burman (PB) and Response Surface Methodology (RSM) experiments, were conducted. The experimental data were then used to develop nonlinear regression models for optimization. Eight process parameters—nozzle temperature, layer thickness, substrate temperature, external perimeter speed, line width, extrusion flow ratio, fill density, and wall layer count—were initially selected, with each parameter tested at two levels (high and low). PB experiments were conducted, and the results revealed that nozzle temperature, external perimeter speed, extrusion flow ratio, and wall layer count significantly affected the flatness error of the printed parts. Based on these findings, a Central Composite Design (CCD) was employed. The results indicated that nozzle temperature (A), external perimeter speed (B), extrusion flow rate (C), and wall layer count (D) were the primary factors influencing the surface flatness of the models. Moreover, significant interaction effects were observed between AC, AD, BC, BD, and CD. Subsequently, nonlinear regression models for the surface flatness were derived using Design-Expert software. MATLAB was used for objective optimization, leading to the optimal parameters: A = 230°C, B = 60 mm/min, C = 0.96, and D = 2. Under these conditions, the signal-to-noise ratio for flatness error reached its maximum value of 42.247. Finally, a model was printed using the optimized parameters, and the results validated the optimization process. This study provides valuable theoretical insights into improving the shape accuracy of FDM-printed PLA components.

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ABSTRACT This study investigates the impact of voltage on the microstructure and corrosion resistance of AZ31B magnesium alloy micro-arc oxidation (MAO) coating. Coatings were prepared at voltages of 300 V, 350 V, 400 V, and 450 V, and their performance was systematically analyzed using scanning electron microscopy (SEM), X-ray diffraction (XRD), electrochemical testing, contact angle measurement, and hardness testing. The findings reveal that as the voltage increases, the coating thickness initially increases before stabilizing, while the surface porosity decreases initially but increases subsequently. The lowest porosity and highest compactness are observed at 350 V. The primary phases of the coating are MgO and Mg2SiO4, with higher voltage promoting the formation of MgO. Hardness and roughness exhibit an initial increase followed by a decrease. Electrochemical tests indicate that the 350 V coating has the lowest corrosion current density, the highest impedance modulus, and the best corrosion resistance. Excessive voltage leads to crack formation on the coating surface, compromising its integrity and corrosion resistance. The study concludes that 350 V optimizes the compactness, phase composition, and surface morphology of the coating, thereby enhancing its corrosion resistance. This provides experimental evidence for optimizing surface protection processes for magnesium alloys.

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ABSTRACT This study investigates the influence of varying tensile stress during decarburization annealing on the magnetic behavior of grain-oriented (GO) electrical steel processed under low slab reheating temperature conditions. Hot-rolled samples were decarburized in a continuous furnace under controlled tensile stresses ranging from 3 to 26 MPa, inducing different degrees of elongation along the rolling direction. After decarburization, the samples underwent nitriding, followed by final annealing in a box furnace. Microstructural evolution was characterized using optical microscopy and Electron Backscatter Diffraction (EBSD), while magnetic performance was assessed using a Single Sheet Tester. The application of tensile stress during primary annealing effectively introduced elongation without compromising the decarburization efficiency, as evidenced by carbon levels below 30 ppm in all conditions. Increased elongation during primary recrystallization was correlated with the formation of coarser secondary grains, which in turn coincided with a significant reduction in magnetic induction under an 800 A/m field and with higher total core losses, particularly in the hysteresis and anomalous loss components. Therefore, by strategically controlling tensile stress and annealing conditions, it is possible to minimize microstructural changes that compromise magnetic performance, thereby promoting lower energy losses in the material.

Abstract in Portuguese:

RESUMO A ABNT NBR 7190 (2022) destaca a importância de 21 propriedades para a caracterização completa da madeira, um material ortotrópico. A pesquisa teve como objetivo avaliar a viabilidade de usar a densidade aparente (ρap) e as durezas nas direções paralela (fh0) e perpendicular (fh90) às fibras como estimadores da resistência (fc0) e da rigidez (Ec0) a compressão na direção paralela às fibras. Modelos de regressão foram aplicados, sendo que o modelo cúbico com ρap apresentou os melhores ajustes (R² aj. entre 73 e 91%). Quando a fh0 foi usada como estimador, os modelos lineares apresentaram R² aj. de 93,98% para fc0 e 64,15% para Ec0. A fh90 teve melhor precisão na estimativa da fc0 (R² aj. = 89,53%) do que na do Ec0 (R² aj. = 61,59%). Modelos de regressão múltipla, combinando dureza e densidade, não mostraram diferença significativa em relação aos modelos com uma variável independente. A aplicação dos modelos a dados experimentais, mostrou erro absoluto nas estimativas variando entre 0,09 e 60%. Esses resultados indicam que densidade e dureza podem ser úteis para a previsão das propriedades mecânicas da madeira, servindo como subsídio para atualizações futuras da norma NBR 7190.

Abstract in English:

ABSTRACT ABNT NBR 7190 (2022) highlights the importance of 21 properties for the full characterization of wood, an orthotropic material. This study evaluated the feasibility of using apparent density (ρap) and hardness parallel (fh0) and perpendicular (fh90) to the grain as estimators of compressive strength (fc0) and stiffness (Ec0) parallel to the grain. Regression models were applied; the cubic model with ρap provided the best fits (adjusted R² between 73% and 91%). When fh0 was used as the estimator, linear models yielded adjusted R² of 93.98% for fc0 and 64.15% for Ec0. For fh90, accuracy was higher for estimating fc0 (adjusted R² = 89.53%) than for Ec0 (adjusted R² = 61.59%). Multiple regression models combining hardness and density did not show significant improvements over single-predictor models. Applying the models to experimental data produced absolute estimation errors ranging from 0.09% to 60%. These findings indicate that density and hardness are useful for predicting the mechanical properties of wood and may inform future updates to NBR 7190.

Abstract in English:

ABSTRACT In the realm of stone processing and quality control, the detection of defects in stone slabs holds significant importance. However, conventional methods rely heavily on manual inspection, which is time-consuming, labour-intensive, and prone to human error. Moreover, the similarity between stone textures and cracks poses a challenge for existing algorithms, often leading to reduced accuracy. To address these issues, we propose YOLOv8-SD, an efficient and lightweight network model tailored for stone slab defect detection. By integrating GhostConv, an inverted residual structure with EMA attention (iEMA), MLLA in the C2f module, and RepHead, our model achieves a balance between detection performance and resource consumption. Experimental results on a self-made dataset demonstrate that YOLOv8-SD outperforms other algorithms, with improvements in precision (P), recall (R), and mean average precision (mAP) by 8.5, 11, and 4.7 percentage points, respectively, while reducing the number of parameters from 3.00M to 2.43M. This makes YOLOv8-SD suitable for deployment on mobile terminal devices.

Abstract in English:

ABSTRACT This study reports dual-sensitive (temperature/pH) mesoporous silica nanoparticles (MSNs) for doxorubicin (DOX) delivery that couple thermo- and pH-triggered gating. The polymer-modified MSNs (≈300 nm) possessed high surface area (≈630 m² g⁻¹) and 2.4-nm channels, enabling ≈22 wt% DOX loading. Spectroscopy confirmed uniform polymer coverage and stable cargo retention. Release was restricted under physiological conditions (pH 7.4, 37°C; ≤ 20% at 24 h) but accelerated by single triggers (42°C or pH 6.5; 35–50% at 24–48 h) and maximized under combined stimuli (pH 6.5, 42°C; ≈80% at 48 h). Blank carriers were cytocompatible in HeLa and MCF-7 cells (>85% viability, 48 h), whereas DOX-loaded particles reduced proliferation with the largest effect under dual-trigger conditions, consistent with polymer coil–globule transition and protonation-assisted release. Varying the pH-sensitive monomer fraction modulated gating and release profiles, allowing tuning of trigger responsiveness. These results demonstrate that integrating thermal and pH cues in a single MSN platform enhances on-demand DOX release and anticancer activity while limiting leakage under physiological conditions.

Abstract in English:

ABSTRACT This study explores the novel use of sugarcane bagasse ash (SBA), an abundant agro-industrial by-product, as a dual replacement for ordinary Portland cement (OPC) and fine aggregate in compressed stabilized earth blocks (CSEBs). Mixtures incorporating 0–10% OPC and 0–25% SBA were prepared to evaluate mechanical strength, durability, and microstructural characteristics. Key tests included water absorption, flexural strength, wet and dry compressive strength, sulfate resistance, mass variation, and stress–strain behavior, while durability was assessed through repeated wetting–drying cycles. Microstructural analysis provided insight into hydration products and surface morphology. Results reveal that CSEBs containing 10% cement and 20% SBA satisfy standard strength requirements and maintain durability under cyclic wetting and drying. Variations in stress–strain behavior were governed primarily by cement dosage when SBA content was constant, underscoring the stabilizing influence of OPC. The study demonstrates that SBA can effectively reduce cement demand while preserving structural performance, offering a sustainable pathway for low-carbon earthen construction. By valorizing an agricultural residue that is often discarded, this approach can lower production costs and greenhouse gas emissions while supporting circular-economy practices. These findings provide a practical framework for scaling SBA-enhanced CSEBs in regions seeking affordable and environmentally responsible building materials.

Abstract in English:

ABSTRACT This research introduces a novel wet-chemical synthesis technique for producing calcium oxide (CaO) nanoparticles from eggshell waste using acetic acid, ethylene diamine tetraacetic acid, and sodium hydroxide. This technology, unlike conventional calcination methods, overcomes high temperatures, reduces energy consumption, and produces nano-CaO with improved homogeneity. The yielded nanoparticles were evaluated using Fourier transform infrared spectroscopy, UV–Visible spectroscopy, X-ray diffraction, transmission electron spectroscopy, elemental analysis, thermal analysis, and surface roughness studies. FTIR analysis confirmed the presence of CaO along with small carbonate and organic remnants, whereas XRD revealed a crystallite size of 60.87 nm and a crystallinity index of 34.12%. TEM scans showed primarily spherical nanoparticles measuring 40–200 nm, with an average size of approximately 147.8 nm, corroborated by AFM roughness measurements (Ra = 13.08 nm). Thermal investigation indicated that the material maintained stability above , aligning with the breakdown of CaCO3 into CaO. The findings suggest that CaO nanoparticles derived from eggshells are advantageous for applications in cementitious composites, water treatment, pharmaceuticals, and polymer fillers, with potential for further optimization to enhance purity and yield.

Abstract in English:

ABSTRACT Cold patch materials for pothole repair are widely used in highway pavement maintenance. To reduce costs and valorize waste streams, this study investigates producing cold patch asphalt mixtures (CPAM) from two types of waste—waste oils and reclaimed asphalt pavement (RAP). Waste engine oil (WEO), cooking waste oil (CWO), and diesel fuel (DF) were used as diluents, and RAP served as the primary aggregate to prepare cold patch asphalt (CPA) and CPAM. The performance of CPA was evaluated via viscosity, volatility, and storage-stability tests; combined with CPAM performance tests, these results were used to determine the optimum diluent dosages, the optimal aggregate gradation, and the optimum RAP content. Results show that the optimum dosages of WEO, CWO, and DF are 35%, 30%, and 25% of the asphalt binder mass, respectively. Under the BL-13-1 gradation, incorporating 70% RAP yields the best pavement performance for CPAM. In terms of climatic suitability, CWO-based CPAM is preferable for rainy regions, whereas DF-based CPAM performs better in hot climates, indicating good overall climate adaptability.

Abstract in English:

ABSTRACT Titanium alloys, particularly Ti-6Al-4V, are among the most widely used materials in biomedical implant applications due to their superior mechanical strength, corrosion resistance, and compatibility with bone tissue. In this study, Ti-6Al-4V substrates were coated with Hydroxyapatite (HA) and Hydroxyapatite reinforced with 1% Graphene (Gr) using electrophoretic deposition under 40V and 80V. The influence of applied voltage, deposition time, and solution composition on coating morphology, thickness, elemental distribution, and structural properties was systematically evaluated. The most favorable results were obtained at 80V, where homogeneous and adherent coatings were formed. Morphological examinations revealed coating thicknesses ranging from 11.25 µm to 87.5 µm. XRD analyses confirmed the presence of Tiα, Tiβ, HA, and Gr phases, demonstrating successful composite coating. Surface characterization showed that HA coatings exhibited hydrophilic behavior, while HA-Gr coatings demonstrated super-hydrophilic properties, which are highly advantageous for cellular attachment and osseointegration. Contact angle and roughness measurements further indicated improved biocompatibility of the composite coatings. These findings suggest that HA-Gr coated Ti-6Al-4V alloys possess enhanced surface properties and hold significant potential as advanced biomaterials for implant applications.

Abstract in English:

ABSTRACT There is a significant problem in Middle Eastern countries with respect to climate change and rainwater management. This research discusses the influence of water-cement ratio (W/C) and aggregate size on pervious concrete strength and permeability. In this research, the impact of different aggregate sizes with different water-cement ratios are examined in the pervious concrete. The main results are that pervious concrete with a 0.4 water-cement ratio and a coarse aggregate of 10 mm got the highest compressive strength (15.7 MPa at 7 days, 16.83 MPa at 28 days). The results show that the W/C directly influenced compression strength, whereas the coarse aggregate’s size directly affected water content, increasing strength. Pervious concrete made with 10 mm aggregate was found to have better compressive strength, flexural strength, and permeability than 20 mm aggregate. Due to working ability, paste coating, and paste density, it acquires strength with a slightly higher water-cement ratio. With a somewhat higher water-cement ratio, the paste contained fewer open pores, which improved the load transfer and enhanced the compressive strength. The void content in the pervious concrete was considerably higher than that of standard concrete, which influenced the formation and strength of hydration products. These findings are instrumental in tuning the performance of pervious concrete to different conditions, especially when its application needs to be more sustainable.

Abstract in Portuguese:

RESUMO A busca pelo reaproveitamento e reciclagem de resíduos industriais vem crescendo em todo o mundo, devido ao desenvolvimento sustentável. As embalagens de ráfia são confeccionadas em polipropileno (PP), e o crescimento da demanda por este tipo de embalagem é uma tendência mundial, visto que tem versatilidade de aplicação em vários setores produtivos, além de apresentarem características como: elevada resistência mecânica, leveza, não absorvem umidade além de serem 100% recicláveis. Porém, grande parte desse material pós-consumo não é reciclada. Este trabalho tem o objetivo de reciclar e reutilizar este material na indústria de formas para o setor calçadista. Realizou-se o processo de reciclagem mecânica das embalagens e produziu-se os compostos reciclados de PP por dois métodos distintos de extrusão. A partir destes materiais foram fabricados formas de calçados em uma indústria do setor. Avaliaram-se os parâmetros térmicos, mecânicos e visuais dos compostos, de outros materiais utilizados nessas indústrias (polipropileno – PP e Polietileno de Alta Densidade - PEAD virgens) e também das formas, verificando suas viabilidades técnicas. Pelos resultados obtidos as amostras de PP virgem e reciclado tem a mesma natureza química, assim como o PEAD. Além disso, observou-se que o PEAD é termicamente mais estável que o PP, e o composto PP Ecowood 1 e 2 apresentaram resultado de temperatura inicial de degradação mais alto que o PP virgem. A amostra do composto PP Ecowood 2 apresentou melhores resultados mecânicos. O índice de fluidez do PP virgem e do composto PP Ecowood 1 e 2 foram semelhantes entre si. As temperaturas de fusão e cristalização do composto PP Ecowood 1 foram superiores ao dos outros compostos, mas os resultados do composto PP Ecowood 2 também foram satisfatórios. Por fim, no que diz respeito ao aspecto visual, a forma produzida com composto PP Ecowood 2 foi a amostra aprovada.

Abstract in English:

ABSTRACT The search for reuse and recycling of industrial waste has been growing worldwide due to sustainable development. Raffia packaging is made of polypropylene (PP), and the growing demand for this type of packaging is a global trend, given its versatility in various production sectors, in addition to offering characteristics such as high mechanical strength, lightness, moisture resistance, and 100% recyclability. However, much of this post-consumer material is not recycled. This study aims to recycle and reuse this material in the lasts industry for the footwear sector. The packaging was mechanically recycled, and recycled PP compounds were produced using two different extrusion methods. From these materials, shoe lasts were manufactured in a factory in the sector. The thermal, mechanical, and visual parameters of the compounds, other materials used in these industries (virgin PP and HDPE), and the lasts were evaluated, verifying their technical feasibility. Based on the results obtained, the virgin and recycled PP samples have the same chemical nature, as does HDPE. Furthermore, it was observed that HDPE is thermally more stable than PP, and the PP Ecowood 1 and 2 compounds presented higher initial degradation temperatures than the virgin PP. The PP Ecowood 2 compound sample presented better mechanical results. The melt flow index of the virgin PP and PP Ecowood 1 and 2 compounds were similar. The melting and crystallization temperatures of the PP Ecowood 1 compound were higher than those of the other compounds, but the results of the PP Ecowood 2 compound were also satisfactory. Finally, regarding the visual appearance, the mold produced with PP Ecowood 2 compound was the approved sample.

Abstract in English:

ABSTRACT The construction industry has been struggling to reduce its carbon emission, and hence the pressing interest in exploring low-carbon alternatives to conventional cement-based products. A sustainable solution is geopolymer concrete (GPC) which exploits industrial and agricultural by-products. This present research explores the viability of replacing a part of fly ash in a GPC mixture with sugarcane bagasse ash (SCBA). The binder system is made of 70% fly ash (FA) and 30% ground granulated blast furnace slag (GGBFS), which are used in combination with 8 and 10 molar alkaline solutions. The SCBA is substituted with fly ash in 5%, 10%, 15%, 20%, and 25%. Twelve mixes are tested on workability, strength, and durability properties. The findings indicated that at 15 percent replacement of SCBA exhibited the most favourable performance in mechanical strength characteristics. The highest 28-day compressive strength achieved is 41.76 MPa in the mix that includes 10 M alkaline solution and 15% SCBA. Furthermore, it was concluded that the interior structure is more compact and refined in comparison to other mixtures. The findings substantiate that SCBA may be efficiently utilized in geopolymer concrete to minimize carbon footprint while ensuring high performance.

Abstract in English:

ABSTRACT This study aims to evaluate the mechanical properties of alkali-treated Prosopis Juliflora (PJ) fiber-reinforced polymer composites and compare them with palm fiber and glass fiber composites. The composites were fabricated using a hand lay-up method with fiber weight ratios of 10%, 15%, and 20%. For tensile strength, treated PJ composites increased from 55 MPa at 10% fiber content to 65 MPa at 20%. Flexural strength improved with treated PJ composites rising from 220 MPa to 240 MPa. The Glass+PJ hybrid composite demonstrated the highest flexural strength, reaching 260 MPa. Impact strength also improved, with treated fibers increasing from 55 J/m to 65 J/m, while Glass+PJ achieved 75 J/m.The novelty of this work lies in presenting the first direct comparative evaluation of alkali-treated Prosopis juliflora, palm, and glass fibre reinforcements within a uniform processing framework, offering insights into the mechanical environmental trade-offs for composite design. However, the present work is limited to short-term laboratory testing and does not include durability assessments such as fatigue or aging studies. The findings demonstrate that properly treated natural fibres, particularly Prosopis juliflora, can serve as cost-effective, lightweight, and sustainable reinforcements for semi-structural and automotive interior applications.

Abstract in Portuguese:

RESUMO Microesferas poliméricas magnéticas à base de metacrilato de glicidila e divinilbenzeno foram sintetizadas via polimerização por suspensão. Foram estudados os efeitos da adição da magnetita (material magnético) na fase aquosa ou na fase orgânica e a razão molar de monômeros sobre suas propriedades finais. Ambos os efeitos influenciaram na quantidade de magnetita incorporada nas microesferas poliméricas e também na sua dispersão. Além disso, a estabilidade térmica destes materiais também foi afetada pela incorporação do material magnético. Partículas poliméricas com morfologia esférica, boa incorporação de óxido de ferro, com comportamento superparamagnético e com magnetização de saturação = 2,73 emu/g foram obtidas com a maior concentração de divinilbenzeno (50% em mol) e adição da magnetita na fase orgânica Os resultados apresentados neste trabalho contribuem para o conhecimento do efeito de parâmetros de síntese ainda pouco explorados na literatura, para preparação de materiais com grande potencial de aplicação em áreas como biotecnologia/biomedicina, catálise, remoção de poluentes e tratamento de efluentes.

Abstract in English:

ABSTRACT Magnetic polymeric microspheres based on glycidyl methacrylate and divinylbenzene were synthesized by suspension polymerization. The effects of adding the magnetite to either the aqueous or organic phase, as well as the monomer molar ratio, on the final properties of the microspheres were investigated. Both parameters affected the incorporation efficiency of the magnetite into the polymeric microspheres and its dispersion within the polymer matrix. In addition, the thermal stability of these materials was also affected by the magnetic material incorporation. Polymeric particles with spherical morphology, good iron oxide incorporation and superparamagnetic behavior (saturation magnetization = 2.73 emu/g) were obtained with 50/50 monomer molar ratios and the organic phase magnetic material addition. The findings of this study enhance the understanding of the influence of underexplored synthesis parameters on the preparation of materials with high potential for application in areas such as biotechnology/biomedicine, catalysis, pollutant removal, and wastewater treatment.

Abstract in English:

ABSTRACT Fiber Reinforced Polymer (FRP) composites, which include sugarcane fiber reinforced, and Silicon Carbide (SiC) filled FRP laminates have evolved as an eco-friendly substitute to traditional materials due to their low weight along with improved mechanical and corrosion properties. Traditional techniques used for evaluating machinability and corrosion do not lead to multi-response behavior, and it appears as if the results are inharmonious too. In the present work, a Taguchi based Machinability and Corrosion Optimization (TM-MCO approach has applied to effectively analyze the influence of important parameters such as feed rate, speed and SiC on complex process factors. It was determined that the tensile strength and impact energy (16.7 J) of the hybrid laminates are 125.6 MPa, and surface roughness can be as low as 1.45 µm at the optimized SiC ratio with minimal tool wear, improved corrosion resistance in salt environments. The innovative approach allows the production of high performance, (low) environmental load products for industrial and long-term environmental degradation and multi-axial loading influence by balancing sustainable material selection with process optimization and scale up these composites for real industrial applications.

Abstract in English:

ABSTRACT The species Euterpe oleracea, commonly known as açaí, produces a fruit whose pulp is extracted and sold throughout Brazil. Its production generates a large volume of waste rich in chemical compounds that can be used as raw material in various industrial segments. In this sense, the extraction of plant nanocellulose has emerged as a suitable alternative to meet current environmental demands for sustainable development. Therefore, the objective of this study was to perform chemical characterization and obtain cellulose nanocrystals (CNC) from the waste generated in the açaí production chain. For the production of nanocellulose, the waste was pretreated with NaClO2 or H2O2, followed by hydrolysis with sulfuric acid (H2SO4). The quantities found for the chemical components in the waste were: 1.5% inorganic compounds, 11.11% total extractives, 25.58% Klason lignin, 62.01% holocellulose, 28.31% alpha-cellulose, and 33.40% hemicelluloses. The pretreatments delignified the material, and acid hydrolysis extracted CNC. The CNC yields from pretreatments with H2O2 and NaClO2, followed by acid hydrolysis, were 58.76% and 0.5%, respectively. The crystallinity index reached 55.31% for the treatment with H2O2. Both pretreatments were effective in delignification and in obtaining nanocellulose, but the hydrolysis conditions in the treatment with NaClO2 should be modified to increase the yield.

Abstract in English:

ABSTRACT Understanding the influence of support interface parameters on part quality is essential for improving the efficiency of Fused Deposition Modeling (FDM) processes. This study investigates the effects of support style, Z-axis distance, and number of top interface layers on surface quality, support removability, and residual material. Eighteen test configurations were printed using PLA material under controlled conditions, following a experimental design with three replications per test. The ease of removal and surface finish were qualitatively evaluated, while surface roughness (Ra, Rz, Rq, Rsk, Rku) was measured quantitatively using a confocal microscope. Results indicate that the Z-axis distance is the dominant factor affecting both surface quality and removability. A 0.2 mm Z-distance yielded the lowest roughness values (Ra ≈ 8.7–9.0 μm) and allowed easy manual detachment without leaving significant residues. In contrast, specimens printed with 0 mm distance exhibited strong bonding, difficult removal, and excessive material residues. The influence of support style was secondary, while the presence of at least one top interface layer improved the overall surface quality. These findings provide quantitative insight into the design and optimization of support parameters in FDM, supporting practical guidelines for integrating Design for Additive Manufacturing principles to enhance print quality and post-processing efficiency.

Abstract in English:

ABSTRACT Natural fiber composites are increasingly recognized as sustainable alternatives to synthetic reinforcements due to their low cost, lightweight nature, and biodegradability. Prosopis juliflora (PJ), an invasive shrub abundant in arid and semi-arid regions, represents an underutilized resource with potential for eco-friendly composite development. This study investigates the mechanical characterization of PJ-based polymer composites, including single-fiber and hybrid combinations with other natural fibers (e.g., Palam). Fibers were extracted, chemically treated (NaOH and HCl), and incorporated into polymer matrices using controlled hand lay-up techniques. Mechanical tests—tensile, flexural, impact, and hardness—were conducted alongside microstructural analyses (SEM/EDAX), chemical characterization (FTIR), and crystallinity assessment (XRD). Results indicate that alkali-treated PJ fibers and certain hybrid composites (e.g., PJ + Palam) exhibit improved tensile and impact properties due to enhanced fiber–matrix adhesion and stress transfer, while flexural performance benefits from optimized fiber orientation and dispersion. Water absorption tests highlight environmental sensitivity, particularly in seawater, and SEM/XRD analyses confirm treatment efficacy without significant cellulose degradation. These findings suggest that PJ fibers, alone or in hybrid configurations, can serve as sustainable, low- to medium-load reinforcement in automotive interior panels, construction panels, and eco-friendly packaging. This study highlights the dual benefit of valorizing an invasive species while providing a renewable composite reinforcement, offering practical insights for sustainable material design.

Abstract in English:

ABSTRACT The aim of this research was to produce and evaluate homogeneous particleboards made from pine wood bonded with recycled polyethylene terephthalate (PETr). To produce the panels, the polymer was ground until it reached an average particle diameter of less than 250 µm, which contributed to an increase in the specific surface area and facilitated the fusion and adhesion to the wood particles. The particulates were homogenized and pressed to consolidate the panels under controlled temperature and pressure (T = 160°C, P = 5.7 N/mm2). Three levels of PETr were proposed (10%–20%–30%) relative to the dry mass of pine particles. The produced panels were evaluated for physical properties such as density, moisture content, thickness swelling, water absorption and surface absorption, as well as mechanical properties including modulus of rupture, modulus of elasticity and internal bond. The Tukey mean contrast test, at a significance level of 5%, was used to verify the influence of PETr content on the physical-mechanical properties of the particleboards. The results indicated that the produced panels met several requirements established by the standards ABNT NBR 14810-2 (2024), ANSI A208.1 (2022), EN 312 (2010) and CS 236-66 (1966), such as P2, M, P1 and T1 respectively, presenting an alternative with a lower environmental impact compared to the panels currently in use.

Abstract in English:

ABSTRACT Synthetic dyes used for wood finishing raise environmental and health concerns due to persistence and toxic aromatic amines, prompting interest in plant-derived colorants for engineered bamboo products. Yet, adoption remains limited by questions about color retention, bonding strength, and potential impacts on veneer mechanics. This study addresses the gap by evaluating safflower-derived quinochalcones—Hydroxysafflor Yellow A (HSYA) and Anhydrosafflor Yellow B (AHSYB)—for bamboo veneer coloration under controlled processing. The objective was to determine extraction efficiency, interfacial interactions, color performance, and durability of HSYA/AHSYB on bamboo veneer. Pigments were obtained via ultrasonic-assisted extraction and applied by hydrothermal coloration; materials were verified and characterized using HPLC, FTIR, UV-Vis, SEM, and colorimetry. AHSYB-colored veneers exhibited higher color strength (K/S) and evidence of enhanced binding attributed to structural modification, while both pigments delivered acceptable wash and rub fastness and only modest losses in mechanical properties (<8%). FTIR indicated robust pigment–cellulose interactions, and mechanical retention was slightly better for HSYA than for AHSYB. The findings support safflower pigments as viable, lower-impact alternatives to synthetic dyes for interior veneer applications, especially where UV exposure is moderate and protective coatings or mordant strategies can be leveraged. Further work should quantify long-term photostability, explore co-pigmentation and antioxidant additives.

Abstract in Portuguese:

RESUMO O setor ferroviário gera resíduos poliméricos que se tornam passivos ambientais incapazes de serem reciclados junto à outras matérias primas, tais como palmilhas e isoladores, devido à contaminação causada pelo desprendimento da carga sobre as linhas férreas. Esses resíduos por vezes são tratados como rejeitos porque não há planos para estender o ciclo de vida do produto, uma alternativa à sua deposição seria sua aplicação como coproduto na indústria da construção civil. Sendo assim, este trabalho se propõe a produzir, avaliar e caracterizar o potencial de blocos modulares de argamassa polimérica provenientes de uma resina baseada em material politereftalato de etileno (PET) para possivelmente ser aplicado no setor da construção civil. Para tanto, foi desenvolvido um método de dosagem de argamassa polimérica para os teores de resina, agregados e material residual para confecção de blocos modulares. As amostras foram caracterizadas quanto a trabalhabilidade no estado fresco e resistência à compressão no estado endurecido. Também foram realizadas análises de microscopia eletrônica de varredura (MEV) para identificação da microestrutura e morfologia, fluorescência de raios x por energia dispersiva (EDXRF) para identificação da composição, área superficial por Brunauer-Emmett-Teller (BET) e análise termogravimétrica (TGA), respectivamente. Os resultados obtidos indicam que os blocos modulares obtidos oferecem uma alternativa sustentável para destinação/reciclagem de resíduos industriais, com potencial de aplicação no setor da construção civil.

Abstract in English:

ABSTRACT The railway sector generates polymeric waste that becomes an environmental liability and cannot be recycled alongside other raw materials, such as insoles and insulators, due to contamination caused by the release of loads on railway lines. This waste is sometimes treated as rejects because there are no plans to extend the product's life cycle. An alternative to its disposal would be its use as a byproduct in the construction industry. Therefore, this work aims to produce, evaluate and characterize the potential of modular polymeric mortar blocks made from a polyethylene terephthalate (PET) based resin to possibly be applied in the construction sector. To this end, a method was developed for dosing polymeric mortar according to the resin, aggregate, and residual material contents for modular block production. The samples were characterized for workability in the fresh state and compressive strength in the hardened state. Scanning electron microscopy (SEM) analyses were also performed to identify the microstructure and morphology, energy-dispersive X-ray fluorescence (EDXRF) to identify the composition, Brunauer-Emmett-Teller (BET) surface area, and thermogravimetric analysis (TGA), respectively. The results indicate that the modular blocks obtained offer a sustainable alternative for the disposal/recycling of industrial waste, with potential application in the construction sector.

Abstract in English:

ABSTRACT Weld overlays and dissimilar joints are widely used in industry. In these applications, where different materials are joined, a mixing region known as the partially mixed zone (PMZ) forms between the base material and the weld metal. The effects of the heat generated, accumulated, and the cooling rate during the process can significantly influence the metallurgical and mechanical properties of the materials. This study aimed to evaluate the thermal effects and the influence of shielding gases on the dissimilar welding of a nickel-based alloy (Inconel 625) onto a low-carbon steel substrate using MIG/MAG welding processes. To determine the most suitable shielding gas, five different gas atmospheres—comprising both inert and active components—were systematically investigated. The methodology involved the use of scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), wavelength-dispersive spectrometry (WDS), and Vickers microhardness testing. The main results indicated an increase in Cr, Ni, Mo, and Nb content and a decrease in iron content in the weld metal for all shielding gases tested. With active gases, variations in the percentage of alloying elements were observed in the weld metal region, indicating elemental diffusion near the PMZ. The most favorable results were obtained with the Ar + 25% He shielding gas, which showed the smallest variation in chemical composition between the PMZ and the weld metal, as well as the highest Ni and Cr contents.

Abstract in Portuguese:

RESUMO Com o avanço da arquitetura no Brasil e a busca por maior flexibilidade nos layouts, tem-se observado crescente uso de lajes lisas protendidas na construção civil. Essa tipologia permite vencer grandes vãos, controla deformações e racionaliza a execução. Este estudo comparou o desempenho estrutural e o consumo de materiais entre lajes convencionais apoiadas em vigas e lajes lisas protendidas com cordoalhas engraxadas. Foi realizado um estudo de caso em uma edificação residencial/comercial em Curitiba (PR), utilizando o software TQS para análise de esforços, deformações, estabilidade global e quantitativos de materiais. Os resultados indicaram que as lajes lisas protendidas apresentaram menores deformações verticais, redução da espessura das lajes e menor consumo de formas, além de maior liberdade arquitetônica. Por outro lado, houve aumento dos deslocamentos horizontais e acréscimo de cerca de 28% no consumo total de aço devido à protensão e às armaduras adicionais. Essas limitações podem ser superadas com ajustes nos pilares e no núcleo rígido, elevando a rigidez global e controlando deslocamentos. Assim, as lajes lisas protendidas mostram-se uma alternativa estrutural eficiente, desde que acompanhadas de um dimensionamento global adequado.

Abstract in English:

ABSTRACT With the advancement of architecture in Brazil and the pursuit of greater flexibility in building layouts, the use of flat post-tensioned slabs in construction has been increasing. This structural system enables longer spans, controls deformations, and rationalizes construction processes. This study compared the structural performance and material consumption between conventional beam-supported slabs and flat post-tensioned slabs with greased strands. A case study was conducted on a residential/commercial building in Curitiba, Brazil, using TQS software to analyze internal forces, deformations, global stability, and material quantities. The results showed that flat post-tensioned slabs exhibited lower vertical deformations, reduced slab thickness, lower formwork consumption, and provided greater architectural flexibility. On the other hand, there was an increase in horizontal displacements and a rise of approximately 28% in total steel consumption due to post-tensioning and the need for additional reinforcement. These limitations can be mitigated through adjustments to the columns and the rigid core, increasing the structure’s global stiffness and controlling displacements. Therefore, flat posttensioned slabs are presented as an efficient and viable structural alternative, provided that they are accompanied by an appropriate global design.

Abstract in English:

ABSTRACT The structural and mechanical properties of Aluminium-Silicon Carbide (Al-SiC) metal matrix composites (MMCs) made by stir casting are investigated when SiC is added at a range from 0% to 10% by weight. The work examines the primary mechanical properties, including tensile strength, flexural strength, impact strength, hardness, and low-velocity impact resistance, as well as microstructure and acoustic emission analyses. The fact that increasing SiC makes the material stronger and tougher is evident in the results, with tensile strength increasing to 349.57 MPa (a 24.5% rise over pure Al), flexural strength reaching 240.85 MPa (a 108.8% increase over pure Al), and hardness reaching 101.25 BHN. With an increased proportion of SiC in the mixture, the ductility and ability to change shape decrease. The addition of SiC results in a steady increase in impact strength, with the highest level of 53.68 kJ/m2 achieved at a 10% concentration, demonstrating the material’s crack resistance. According to the research, Al-SiC MMCs exhibit the best mechanical properties for aerospace and automotive applications when the reinforcement levels are just right. Hybrid reinforcements or small SiC fibers may be examined in future work to reduce brittleness while retaining the best features.

Abstract in English:

ABSTRACT This study investigates the influence of thermal shock on the mechanical and microstructural properties of M20-grade concrete. A total of 15 cylinders, 9 cubes, and 4 prisms were cast and subjected to fire exposure using an LPG burner, reaching approximately 800 °C for 90 minutes, followed by sudden water quenching to simulate thermal shock. The specimens were tested for compressive, split tensile, and flexural strengths, and compared with unheated control samples. The thermoshocked concrete exhibited significant strength reductions: compressive strength decreased by 42.8%, split tensile strength by 26.9%, and flexural strength by 50.1%. Weight loss averaged 8–10%, indicating moisture evaporation and matrix degradation. FESEM analysis revealed severe microcracking, increased porosity, and decomposition of C–S–H and CH, while XRD confirmed phase transformations from C–S–H to AN and CC. A strong linear correlation (R2 = 0.91) was observed between mass loss and strength reduction. The results demonstrate that rapid cooling after fire exposure critically weakens the microstructure and mechanical integrity of concrete, emphasizing the need to evaluate residual performance in post-fire structures.

Abstract in Portuguese:

RESUMO O presente estudo aborda a análise do comportamento mecânico de vigas de concreto armado submetidas a carregamentos lineares, com ênfase na influência das condições de dois diferentes tipos de apoio —simples ou engastados— sobre a resposta estrutural. O objetivo principal desta pesquisa é preencher uma lacuna na literatura, que tradicionalmente se concentra em vigas com apoio simples, deixando de considerar outros tipos de apoios. Foi desenvolvido um modelo numérico no software ABAQUS®, validado com base nos parâmetros da ABNT NBR 6118, considerando armaduras longitudinais e transversais, e utilizando o modelo constitutivo Concrete Damaged Plasticity (CDP) para simulação do concreto. A viga de concreto armado analisada, por meio de experimentação numérica, apresenta geometria e armadura idênticas sob duas condições de apoio distintas: bi-apoiada e bi-engastada. A análise comparativa demonstrou que as vigas com apoios engastados (Ve) apresentam resistência a cargas até 15,9% superiores e deslocamento 29,8% inferior em comparação às vigas com apoios simples (Va). Ademais, as formas de ruptura diferem conforme o tipo de apoio, sendo que a viga Ve rompe pelo fendilhamento da biela gerada pelo cisalhamento, enquanto a Va falha pelo esmagamento do concreto decorrente da flexão no momento positivo. As simulações numéricas demonstraram uma correlação satisfatória com os resultados analíticos, apresentando variações entre 5,9% e 15,5%, validando, portanto, o modelo utilizado. Este trabalho contribui para o entendimento do impacto dos apoios na resistência e deformabilidade das vigas de concreto armado. Para investigações futuras, sugere-se a realização de ensaios experimentais com diferentes configurações de carregamento e apoio, com o objetivo de expandir a base de dados e validar os modelos numéricos em escala real.

Abstract in English:

ABSTRACT This study analyzes the mechanical behavior of reinforced concrete beams subjected to linear loads, emphasizing the influence of two different types of support conditions— movable or fixed —on the structural response. The central objective of this research endeavor is to address a significant lacuna in the extant literature, which has historically concentrated on beams with simple support, while disregarding other types of supports. A numerical model was developed in ABAQUS® software and validated based on the parameters of ABNT NBR 6118. The model considers longitudinal and transverse reinforcement and uses the Concrete Damaged Plasticity (CDP) constitutive model to simulate concrete. The reinforced concrete beam that was analyzed through numerical experimentation has identical geometry and reinforcement under two different support conditions: double-supported and double-fixed. The comparative analysis demonstrated that beams with fixed supports (Ve) exhibited up to 15,9% higher load resistance and 29,8% lower displacement compared to beams with movable supports (Va). Furthermore, the forms of rupture differ according to the type of support, with the Ve beam rupturing due to cracking of the connecting rod generated by shear, while the Va beam fails due to crushing of the concrete resulting from bending at the positive moment. The numerical simulations demonstrated a satisfactory correlation with the analytical results, exhibiting variations between 5,9% and 15.5%. This finding validates the model employed. This work contributes to the understanding of the impact of supports on the strength and deformability of reinforced concrete beams. It is recommended that subsequent investigations involve experimental tests with varying loading and support configurations. The objective of these tests is twofold: first, to expand the existing database, and second, to validate the numerical models on a real scale.

Abstract in English:

ABSTRACT This study investigates the potential of waste Polyurethane Foam (PF) as a lightweight coarse aggregate in concrete, aiming to promote sustainable construction practices by recycling industrial waste. Waste PF was used as coarse aggregate in concrete mixes, replacing 0–80% by volume in 10% increments. These mixes were tested for compressive strength, split tensile strength, and flexural strength. Correlations between compressive, split tensile, and flexural strengths were derived and compared with international code predictions. Additionally, microstructural investigations using Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray Analysis (EDAX) were conducted. Furthermore, the embodied carbon dioxide emissions and eco-strength efficiency of the mixes were calculated to evaluate their environmental performance. The results indicate that mixes with 30 to 60% Polyurethane Foam Aggregate (PFA) achieved compressive strengths above 17 MPa and density below 2000 kg/m3, thereby meeting the structural lightweight concrete requirements of ACI 213R, with all mixes showing split tensile and flexural strengths above 2 MPa. A strong correlation was found among mechanical strengths, confirming the reliability of experimental results. SEM images showed enhanced bonding between PFA and the cement matrix. The eco-strength efficiency of polyurethane foam concrete mixes dropped by 24–43% at 30–60% replacement compared to conventional concrete.

Abstract in English:

ABSTRACT In this study, Aluminium wire mesh (ALWM) reinforced Polypropylene (AP) composite and Flax woven fabric + ALWM reinforced polypropylene (FAP) hybrid composites were fabricated using stacking film technique and cured in hot press machine. Various configurations of FAP hybrid composites were processed based on the composition of flax fiber, polypropylene (PP) and ALWM. Composites comprising flax fiber content of 30, 32.5, 35, 37.5 and 40wt.%, with constant loading of 10wt.% of ALWM, and remaining weight fraction of PP were designated as, FAP1, FAP2, FAP3, FAP4 and FAP5, respectively. Experimental results showed that Increased in the flax fiber content had influenced positive impact on the tensile, flexural and impact properties of the FAP composites. Amongst the developed plastics, FAP4 dominated due to strong interfacial adhesion between ALWM, flax fiber and PP matrix. However, synergetic effect of ALWM, and flax fiber was noticed in case of tensile modulus, where FAP5 exhibited higher than other laminates. Statistical validation of the mechanical results was confirmed by one way ANOVA and Tukey’s test. Field Emission Scanning Electron Microscope (FESEM) examination exposed fiber pullouts, dislocation of ALWM, matrix peeling, broken fiber, crack propagation, fiber bridging endured by the samples.

Abstract in English:

ABSTRACT Studies on polymer composites exposed to contact fluids like crude oil remain limited, particularly when natural fibers are used as reinforcement. This work investigates the mechanical behavior of four laminate configurations: a fiberglass mat laminate (MG), two hybrid laminates with interlaminar arrangements of sisal/glass (IGS) and jute/glass (IGJ), and a laminate made entirely of jute fabric (TJ). The specimens were immersed in crude oil and distilled water until saturation, and some received resin edge protection to reduce moisture ingress. All laminates underwent three-point bending tests to assess mechanical degradation, followed by microstructural evaluation. Results showed that crude oil exposure led to moderate reductions about 20% in flexural strength and 9% in stiffness while distilled water caused more severe losses, exceeding 40% in both properties. Macroscopic fracture analysis revealed distinct failure zones with limited visible damage, whereas microscopic inspection indicated polymer matrix degradation, fiber–matrix debonding, and oil infiltration, influenced by fluid exposure duration and mechanical loading. Resin edge protection proved beneficial for jute-based laminates (TJ and IGJ), helping preserve mechanical integrity. These outcomes highlight the viability of hybrid natural/synthetic fiber composites for use in demanding industrial settings, such as oil and marine applications, where durability against moisture and chemical agents is essential.

Abstract in English:

ABSTRACT This study investigated the effect of environmentally sustainable dielectric fluids composed of a 5 wt.% ionic liquid (IL) blend of vegetable oils (sunflower, coconut, corn and neem) on the performance of electrical discharge machining (EDM) of Inconel 718. A copper square electrode was used with controlled variations in gap voltage, discharge current, pulse interval and pulse duration. Key performance metrics such as material removal rate (MRR), recast layer thickness (RLT) and residual stress (RS) were evaluated. Among the combinations tested, corn oil mixed with ionic liquid delivered the highest MRR. Dielectrics with higher constants enhanced spark penetration, but produced thicker recast layers; conversely, those with lower constants yielded smoother surfaces and reduced recast layer thickness. RS levels were also found to be linked to dielectric properties: higher constants generated stronger sparks and elevated stress, whereas oils such as neem, which have lower constants, provided a better thermal balance and minimized stress. X-ray diffraction (XRD) analysis showed the presence of γ-Ni, Cu-Ni, Ni3Nb and Ni3C phases consistently across all conditions. Coconut and corn oils encouraged carbide formation, whereas ionic liquid blends resulted in nitrides, fluorides, and phosphides due to their reactive constituents.

Abstract in Portuguese:

RESUMO Devido a relação entre resistência mecânica e peso específico, excelente desempenho térmico e acústico e baixo impacto ambiental se comparados com o aço e concreto armado, a madeira vem sendo crescentemente utilizada na construção. No Brasil, a madeira tem sido frequentemente considerada para o projeto de estruturas de cobertura, especialmente em treliças planas industrializadas. Entretanto, a instabilidade em compressão no eixo de menor momento de inércia consiste em um fator crítico no dimensionamento, podendo impactar negativamente na análise da confiabilidade estrutural devido à espessura reduzida dos elementos de barra componentes. Assim, esta pesquisa visou avaliar a confiabilidade estrutural de estruturas de treliças planas industrializadas de madeira da espécie Eucalyptus saligna considerando-se três tipologias: Howe, Pratt e Fink. A metodologia se centrou na Simulação de Monte Carlo para obter índices de confiabilidade e comparar com os índices mínimos exigidos pela norma europeia EN 1990, visando analisar a segurança estrutural dessas treliças em aplicações típicas na construção. Os resultados revelaram que nenhuma das três tipologias atingiu o índice mínimo de confiabilidade estabelecido pela norma europeia, fato esse que requer a atenção de projetistas e de normalizadores e justifica a importância da adoção de reforços estruturais e do aumento da espessura dos componentes.

Abstract in English:

ABSTRACT Due to the relationship between mechanical strength and specific weight, excellent thermal and acoustic performance, and lower environmental impact compared to steel and reinforced concrete, wood has been increasingly used in construction. In Brazil, timber has often been considered for the design of roof structures, especially in industrialized trusses. However, compression instability about the axis with the smaller moment of inertia is a critical factor in the design, which can negatively affect the structural reliability analysis of the wood due to the reduced thickness of the constituent bar elements. Thus, this research aimed to evaluate the structural reliability of industrialized timber planar truss structures of the species Eucalyptus saligna, considering three typologies: Howe, Pratt, and Fink. The methodology focused on Monte Carlo Simulation to obtain reliability indices and compare them with the minimum indices required by the European standard EN 1990, aiming to analyze the structural safety of these trusses in typical applications in construction. The results showed that none of the three typologies reached the minimum reliability index established by the European standard, a fact that requires the attention of designers and standardization bodies and justifies the importance of adopting structural reinforcements and increasing the thickness of the components.