Resumo em Inglês:

Concrete is an unavoidable element in modern construction. During concrete production enormous amount of CO2 is emitted which results in global warming. From the point of view of environmental protection, sustainable concrete production should be focused on. An eco-friendly solution to lessen the impact on the environment has been briefed in this article. Ground Granulated Blast furnace Slag (GGBS) and cement kiln dust have been partially replaced with cement. The strength and durability properties of GGBS and cement kiln dust-incorporated concrete were evaluated and presented. The optimal substitution percentage of GGBS and cement kiln dust was reckoned as 15% and 12% respectively. The test results fortified that the replacement of GGBS and cement kiln dust for cement in concrete becomes an eco-friendly solution from the point of view of quality and sustainability.

Resumo em Inglês:

In the present study, Response Surface Methodology model (RSM) and Artificial Neural Network model (ANN) is presented to forecast the ultimate moment capacity of ferrocement using 2 variable process modelling (volume fraction and steel slag replacement). The RSM and ANN model’s outcomes are contrasted with those of other existing models, like plastic analysis, mechnaism approcah, simplified method, group method of data handling, the results shows that ferrocement with steel slag replacement of 25% and chicken mesh volume fraction (Vr) of 4.35% has maximum experimental moment capacity of 253.33 kN-mm and predicted moment capacity using RSM and ANN is 244.70 kNmm and 255.88 kNmm respectively. The adopted ANN have a regression value of 0.9882 and 0.98863 for training and testing respectively. The outcomes of the analysis of variance show that the provided models are very suitable since the p value is less than 0.005, the projected R2 and the adjustable R2 is less than 20%. Moreover, the flexural moment of ferrocement composites is more significantly affected by the Vr. According to the findings of the surface plot, Pareto chart, and regression analysis, the Vr is the most important and crucial factor for the flexural moment of ferrocement composites.

Resumo em Inglês:

Sand mining from riverbeds has been a vital component of the construction industry for decades, providing a fundamental ingredient for concrete production. However, the indiscriminate extraction of sand from riverbeds led to serious environmental issues, like erosion of riverbeds, destruction of aquatic habitats and increased susceptibility to flooding which emphasizes the necessity of finding alternate materials. Recent studies on Weathered Crystalline Rock, a soft upper layer in quarries – often discarded as waste – have shown that WCR-sand could be a viable alternative to fine-aggregates in concrete thereby alleviating the environmental impacts caused by the extraction of natural resources. Five mixes of M65 grade concrete with sand replacement of 5%, 10%, 15% and 20% with WCR-sand were prepared, cured for maximum 90 days and tested for mechanical and durability properties. Results obtained led to the conclusion that WCR-sand can be a partial replacement up to 5% – theoretically and even up to 10% practically – of sand in concrete without affecting the mechanical and durability properties. This could potentially reduce sand-mining and rock-quarrying up-to 5 to 10% which not only helps curb the depletion of natural resources, a major environmental concern today, but aids in managing waste materials from quarrying.

Resumo em Inglês:

This study delves into the utilization of advanced materials to enhance the mechanical characteristics and longevity of concrete structures, with a specific focus on the performance and design of beams composed of light gauge steel hollow sections (LGSHS) filled with steel fiber-reinforced concrete (SFRC) under flexural conditions. SFRC, known for its exceptional fire resistance, emerges as a promising alternative to Ordinary Portland Cement (OPC) in elevating concrete properties. The experimental and numerical findings consistently demonstrated a noteworthy 12% increase in maximum loading capacity, exhibiting a consistent curved trend at the moment against mid-span displacement when employing the composite material. Finite Element Analysis (FEA) modeling was used to scrutinize core concrete failure patterns, residual displacements of external metal during the load-carrying process, and load distribution patterns throughout the structural element. The infusion of SFRC into light gauge steel sections was found to enhance load-carrying capacity, ductility, and toughness. This paper scrutinizes the mechanical properties and structural behavior of LGSHS filled with SFRC, encompassing steel and concrete properties, member geometry, and response to fire exposure. The primary objective is to assess the load-deformation characteristics of rectangular hollow beams formed by concrete-filled steel tubes (CFST) filled with SFRC. The investigation aims to determine load-carrying capacity, strain, deformation capacity, ductility, and failure characteristics under ambient and elevated temperatures.

Resumo em Inglês:

This study investigates the mechanical properties of thermoplastic polyurethane (TPU) composites reinforced with multi-walled carbon nanotubes (MWCNTs) for application in athletic protective gear. The objectives were to (1) systematically evaluate the effects of MWCNT loading level and alignment on the tensile, compressive, hardness, and impact properties; (2) identify an optimal MWCNT content range for balanced enhancements; and (3) explore scalable fabrication methods. MWCNT/TPU composites with 0.5–4 wt% loading were prepared by solution mixing and compression molding. Mechanical testing revealed significant improvements, with 62 MPa tensile strength (+19%), 507 MPa modulus (+23%), and 10% higher impact energy absorption achieved at 1–4 wt% MWCNT. MWCNT alignment further enhanced the properties, while loadings above 2 wt% showed some embrittlement. Microstructural characterization evidenced good MWCNT dispersion and interfacial bonding. The results demonstrate that low MWCNT additions can substantially enhance the strength, stiffness, and impact resistance of TPU. This indicates great potential for developing advanced, lightweight athletic protective equipment like helmets and pads with improved energy absorption and durability. Future work will focus on optimizing composite processing and design for specific gear applications.

Resumo em Português:

RESUMO O bisfenol A (BPA) é utilizado como matéria prima na fabricação do plástico e apresenta-se como um desregulador endócrino. Foi realizado o desenvolvimento e a validação de um método voltamétrico para determinação de BPA e o método foi baseado em sensores descartáveis de carbono modificados com carbon black. A voltametria de onda quadrada foi selecionada para a determinação do BPA em amostras de água mineral, comercializadas em garrafas plásticas, e este método foi validado por meio das figuras de mérito. Observou-se uma resposta linear no intervalo de concentração de 6,10 a 27,4 µmol L–1, com valores de limites de detecção e de quantificação iguais a 0,137 µmol L–1 e 0,416 µmol L–1, respectivamente. O método demonstrou seletividade adequada e boa precisão, com desvios padrão relativos entre 0,59 e 9,89%, estando abaixo do limite indicado para esta faixa de concentração. A estimativa da exatidão, em termos de recuperação média, foi obtida na faixa de 58,16 e 118,79%, estando dentro dos limites estabelecidos por órgãos reguladores. Deste modo, os resultados obtidos neste trabalho são viáveis frente a outros trabalhos já reportados na literatura para a determinação de BPA, apresentando-se como uma alternativa rápida e de baixo custo para o monitoramento deste contaminante.

Resumo em Inglês:

ABSTRACT The bisphenol A (BPA) is a raw material in plastic manufacturing and is known as an endocrine disruptor. The development and validation of a voltammetric method for BPA determination were carried out, based on disposable carbon sensors modified with carbon black. Square-wave voltammetry was selected for BPA determination in mineral water samples, marketed in plastic bottles, and this method was validated using figures of merit. A linear response was observed in the concentration range of 6.10 to 27.4 µmol L–1, with detection and quantification limits values of 0.137 µmol L–1 and 0.416 µmol L–1, respectively. The method demonstrated adequate selectivity and good precision, with relative standard deviations ranging from 0.59 to 9.89%, which were below the indicated limit for this concentration range. Accuracy estimation, in terms of average recovery, ranged from 58.16 to 118.79%, falling within the limits established by regulatory agencies. Thus, the results obtained in this study are viable compared to other studies reported in the literature for BPA determination, presenting themselves as a rapid and cost-effective alternative for monitoring this contaminant.

Resumo em Inglês:

ABSTRACT Emulsified asphalt is commonly used in highway engineering as a binder for interlayer bonding, slurry seals, micro-surfacing, and cold recycled asphalt mixtures. Its storage stability is a common technical challenge in the field. The preparation process of emulsified asphalt significantly impacts its storage stability. This paper examines the effects of emulsion pH, asphalt temperature, and shearing time on the storage stability of emulsified asphalt and the particle size of asphalt droplets. The morphological evolution of asphalt droplets was observed using fluorescence microscopy, and the principles of emulsion sedimentation were elucidated. Based on this, the optimal preparation conditions for emulsified asphalt were determined using response surface methodology. The results indicate that emulsion pH, asphalt temperature, and shearing time significantly affect the particle size of emulsified asphalt droplets and their storage stability. Emulsified asphalts with a larger number of droplets and smaller particle sizes exhibit superior storage stability. Furthermore, the correlation between the D50 particle size of asphalt droplets and the storage stability of emulsified asphalt is stronger than that of D10 and D90, making D50 a more suitable indicator for predicting and assessing the storage stability of emulsified asphalt. Finally, the response surface optimization identified the optimal preparation conditions for emulsified asphalt as an emulsion pH of 3.2, an asphalt temperature of 137.3°C, and a shearing time of 74 seconds.

Resumo em Português:

RESUMO O setor da construção civil desempenha um papel fundamental no desenvolvimento social, mas é responsável pelo consumo de recursos naturais e energéticos do mundo. Portanto, as pesquisas buscam incorporar resíduos na produção de materiais, alinhando-se com metas globais de redução das emissões de CO2, descarte em aterros sanitários e extração dos recursos. Entre os resíduos industrias, destaca-se o resíduo proveniente do processo de lapidação do vidro (RLV), pouco explorado na literatura e com taxas significativas de descarte em aterros. Assim, esta pesquisa tem como objetivo avaliar as propriedades de argamassas com incorporação de RLV, em substituição parcial ao cimento Portland e ao agregado, por meio de uma investigação abrangente das propriedades do material produzido. Os materiais componentes das misturas e as argamassas foram caracterizados de acordo com as prescrições normativas. Os dados obtidos foram analisados por meio da metodologia de análise de variância (ANOVA) e teste de Tukey. Os resultados mostraram que o RLV influenciou no índice de consistência, na massa específica real e na aderência à tração das argamassas, reduziu a absorção de água, absorção por capilaridade e retração. Quanto à resistência à compressão, observou-se que até 10% pelo RLV, em substituição ao cimento, não compromete esta propriedade, havendo aumento relativo de resistência, quando em substituição à areia. Já para a durabilidade, houve uma melhoria nesta propriedade. Conclui-se que a utilização de RLV, em substituição parcial ao cimento Portland e ao agregado miúdo, na produção de argamassas é uma alternativa técnica, pois apresentou desempenho que possibilita seu uso, e atende aos princípios do desenvolvimento sustentável, os quais apresentam alternativas capazes de contribuir para a economia de energia e recursos naturais.

Resumo em Inglês:

ABSTRACT The construction sector plays a fundamental role in social development, but is responsible for the consumption of the world’s natural and energy resources. Therefore, research seeks to incorporate waste into the production of materials, aligning with global goals for reducing CO2 emissions, disposal in landfills and resource extraction. Among industrial waste, waste from the glass cutting process (GCW) stands out, little explored in the literature and with significant rates of disposal in landfills. Therefore, this research aims to evaluate the properties of mortars incorporating GCW, as a partial replacement for Portland cement and aggregate, through a comprehensive investigation of the properties of the material produced. The materials that make up the mixtures and mortars were characterized in accordance with regulatory requirements. The data obtained were analyzed using the analysis of variance (ANOVA) methodology and Tukey test. The results showed that the GCW influenced the consistency index, the specific gravity and the tensile bond strength of the mortars, reducing water absorption, capillary absorption and shrinkage. As for compressive strength, it was observed that up to 10% by GCW, replacing cement, does not compromise this property, with a relative increase in strength when replacing sand. As for durability, there was an improvement in this property. It is concluded that the use of GCW, in partial replacement of Portland cement and fine aggregate, in the production of mortars is a technical alternative, as it presented performance that enables its use, and meets the principles of sustainable development, which present capable alternatives to contribute to saving energy and natural resources.

Resumo em Inglês:

The study aims to optimize machining parameters for turning SAE 8822 Alloy steel under green machining (without coolant), using a CNC turning machine with a carbide tool. The controlled factors are spindle speed (A), feed rate (B), and depth of cut (C), with roughness (Ra) as the response variable. The experimental runs are conducted using an L9 Orthogonal Array (OA). Orthogonal arrays are used to efficiently explore the parameter space with a relatively small number of experimental runs while maintaining statistical validity. The impact of the machining parameters on the roughness is interpreted using Analysis of Variance (ANOVA). ANOVA is a statistical technique that helps identify the significance of each parameter and their interactions on the response variable. The result indicated that variation of A between 1500 rpm to 2000 rpm resulted in a significant increase in Ra. Similarly, the effect of B and C contributed towards huge variations in Ra. The optimal values of 1500 rpm for A, 0.5 mm/rev for B, and 1 mm for C are identified as the most favorable combination for achieving the desired Ra. Achieving a minimum Ra of 0.04 microns indicate a very high-quality surface, which may be desirable in precision engineering applications. The analysis shows that the C and B have the highest influence followed by A on Ra.

Resumo em Português:

ABSTRACT Population growth and the high demand for the use of wood already consolidated on the market have caused a high demand for forestry resources. This factor motivated the search for other species with properties that satisfy everyday needs in industrial applications. The research aims to characterize the physical-mechanical properties of Anthocleista grandiflora wood. Samples were taken to determine the properties of the three trunks’ base, middle, and top regions at 38, 43, and 47-year-old. Physical (density, moisture content, and volumetric increase) and mechanical tests (flexural strength, elasticity resistance, shear strength, and Janka hardness) were used to characterize the material. The results confirmed that the lowest average moisture content was presented at the base of 38-year-old trees, with values varying from 12.2 to 13.3% in the heartwood and sapwood regions. For density, the base of 47-year-old trees obtained the highest values, with a variation of 434.3–477.3 kg m–3 in the heartwood and sapwood regions. Mechanical flexural strength tests demonstrated that the highest value for the modulus of rupture was 63 MPa, indicated by samples taken from the heartwood of 43-year-old trees. The results show that A. Grandiflora wood can be used for various value-added purposes (construction, furniture, and other equipment).

Resumo em Inglês:

ABSTRACT For structural strengthening and retrofitting, advanced composite materials like carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer (GFRP) are frequently utilized. Applications in civil engineering require a thorough understanding of the behaviour and response of such materials. To forecast the stress-strain behaviour, the current research focuses on the numerical simulation of CFRP and GFRP-reinforced concrete specimens. ABAQUS was used to model a concrete specimen using the C3D8R solid element. The material modeling has considered the nonlinear compression behaviour of concrete and the linear elastic compression behaviour of CFRP/GFRP. The research examined gains in load-carrying capacity compared to concrete of normal strength and confined to unconfined strengths. The validity of numerical simulation has been confirmed through comparison with published experimental results. Additionally, the impact of the number of layers is carefully examined. Additionally, a comparison of the stress-strain characteristics of specimens enhanced with GFRP and CFRP has been conducted.

Resumo em Inglês:

Abstract In this work, the microstructure evolution and mechanical properties of 6201 aluminum alloy during multi-directional forging (MDF) and solution-aging were systematically studied. In the MDF process, the deformation of 6201 aluminum alloy was not uniform, and the increase of forging passes can effectively improve the inhomogeneity. With the increase of forging passes, the alloy changed from dynamic recovery to dynamic recrystallization, the grains in the center were refined obviously, and the anisotropy of microstructure was eliminated. After 9 passes of MDF followed by the solution-aging, the re-dissolution and re-precipitation behavior of the second phases significantly improved the mechanical properties of the alloy. The tensile strength, yield strength, elongation and conductivity of the alloy were 257 MPa, 139 MPa, 16.1%, 51.6% IACS, respectively, 55.8%, 73.8%, 3.4% and 10.5% higher than that of the as-cast alloy. At the same time, the average grain size of the alloy was decreased to 133 μm, 50.9% lower than that of the initial one.

Resumo em Inglês:

abstract This study presents an innovative crude oil heating technology by introducing environmentally friendly solar energy into the petroleum industry. By integrating novel combination methods into traditional crude oil heating systems, a versatile and efficient crude oil heating system has been formed. The system was implemented in a refinery and its thermodynamic and economic performance was analyzed. The thermodynamic analysis, employing the exergy analysis method, reveals that among the considered parameters, compressor pressure ratio and Rankine cycle fluid flow rate exert the most significant influence on system efficiency. Overall, the system achieves energy efficiency, exergy efficiency, and waste heat recovery efficiency of 75.99%, 74.13%, and 31.21%, respectively. Within the system, solar collectors, TES tank, and compressor exhibit the highest exergy destruction rates, while pumps demonstrate the lowest exergy destruction rate. The economic analysis, using the annualized cost method, revealed that electricity prices have a significant impact on the economic performance of the system. The variation in system economic parameters is related to the annualized operating cost of the system. The system generates a net annual benefit of 0.591 million US$, with a 4.124-year investment return period. Moreover, Sensitivity analysis explores various factors affecting the crude oil heating system’s performance.

Resumo em Inglês:

Abstract Due to collapse of buildings, the earthquakes in India and other countries have resulted in the death of people and damage to property. While it is impossible to prevent earthquakes, it is possible to lessen the damage they cause to existing structures by taking the necessary measures. It becomes crucial to perform an assessment first, then identify the weak members, and finally, carry out the necessary strengthening. Using pushover analysis, this study aims to evaluate the existing R.C. building in Zone-III. The analysis research shows the building’s performance levels, component behaviour, failure mechanism, and hinge formation. Externally wrapped GFRP sheets were used to strengthen the existing member’s deficiency.

Resumo em Português:

RESUMO Este trabalho visa analisar a evolução morfológica de uma liga comercial de alumínio A332 produzida via lingotamento contínuo convencional durante o processo de tixoconformação. A caracterização da transição sólido-líquido, ou seja, as temperaturas de trabalho correspondentes as frações sólidas de 77%, 67% e 52% foram determinadas via ensaios de análise térmica de calorimetria diferencial de varredura (DSC), na sequência a liga foi reaquecida até as temperaturas de trabalho e mantidas pelos tempos de tratamento de 0 s, 30 s e 90 s. Por meio da metalografia convencional observou-se o aumento no seu tamanho durante a manutenção da liga à faixa semissólida para o tempo de 90 s de tratamento sendo o principal mecanismo para essa alteração o fenômeno de ostwald ripening seguido por coalescência. Tem-se que a menor fração sólida proporcionou maiores valores de tamanho de glóbulos primários e de grãos, porém apresentou baixos valores de viscosidade aparente em torno de 105 Pa.s devido a menor presença de fase sólida na estrutura da liga e consequentemente menor resistência ao escoamento. Este baixo valor de viscosidade aparente torna a liga propícia a ser utilizada como matéria-prima nos processos de tixoconformação.

Resumo em Inglês:

ABSTRACT This work aims to analyze the morphological evolution of the commercial A332 aluminum alloy produced via direct casting during the thixoforming process. The characterization of the solid-liquid transition, that is, the working temperatures corresponding to the solid fractions of 77%, 67% and 52% were determined via differential scanning calorimetry (DSC) tests, then the alloy was reheated until the temperature of and maintained for 0 s, 30 s and 90 s treatment times. Through conventional metallography, an increase in the size was observed during the maintenance of the alloy to the semi-solid band for the time of 90 s of treatment being the main mechanism for this change is the phenomenon of ostwald ripening followed by coalescence. It is known that the smallest solid fraction provided higher values of size of primary globules and grains, however, it presented low values of apparent viscosity around 105 Pa.s due to the lower presence of solid phase in the alloy structure and consequently less resistance to flow. This value low apparent viscosity makes the alloy suitable for used as a raw material in thixoforming processes.

Resumo em Inglês:

ABSTRACT This study examines the effects of using crushed Printed Circuit Board (PCB) (also known as E-waste aggregate) in concrete as a partial substitute for regular coarse aggregate (NCA). M25 grade concrete was utilized. After substituting 0%, 10%, and 15% of the natural coarse aggregates with E-waste aggregate, three combinations were still complete. Verified examples continue to focus on strength attributes, after which long-lasting characteristics such as aquatic concentration, thermal expansion, and abrasion encounter tests were carried out. Test results proved that when the replacement percentage of Electronic waste aggregate was higher significant reduction in strength properties was noticed. It is container remains credited to the reality that incorporation of E-waste aggregate slows down the hydration process that would lead to a significant loss in strength. However, it was observed that mix made with 10% and 15% E-waste aggregate shows better resistance against durability properties than control mix concrete. It was also observed that utmost care should be taken for maintaining proper workability and removal of toxic substances in E-waste aggregate for better forte and toughness properties.

Resumo em Inglês:

The microstructure, mechanical properties, and heat treatment process relationships of 45MnVS non-tempered steel were investigated. Different grain sizes and tissue ratios were obtained after heating and holding at 950, 1050, and 1150 °C for 30 min, respectively, and cooling at different cooling conditions and cooling rates. As the austenitizing temperature increased, the grain size and the elongation and section shrinkage of the experimental steels decreased. At the same time, the content of ferrite and pearlite in the tissue gradually decreases, the content of sorbite and troostite rises, and the strength and hardness of the experimental steel increase. With the increase of cold speed, ferrite’s content decreases, sorbite and troostite’s content increases, and strength and hardness increase. The original austenite grain size also influences the tissue ratio. As the austenite grain refines, the ferrite transformation temperature increases during cooling and the ferrite content in the tissue rises after cooling.

Resumo em Português:

RESUMO O uso de Concreto Leve com Pérolas de EPS (CLEPE) em lajes estruturais surge como uma alternativa economicamente atrativa para reduzir o peso próprio das estruturas de concreto armado. Contudo, a modificação da massa estrutural e a substituição do agregado graúdo convencional pelo EPS impactam diretamente as propriedades dinâmicas da estrutura. Neste contexto, o objetivo deste estudo é investigar a influência da substituição do Concreto Convencional (CC) pelo CLEPE nas propriedades dinâmicas da estrutura, considerando o impacto da diminuição significativa de massa e rigidez do material. Para a determinação dos parâmetros dinâmicos, como frequências naturais, deformações modais e fatores de amortecimento, foram realizados experimentos em corpos de prova cilíndricos e lajes retangulares, empregando métodos de análise modal estocástica e ensaio dinâmico de resposta acústica. Os resultados revelam clareza nas deformações modais e uma aproximação satisfatória entre as frequências naturais experimentais e numéricas. Em relação ao fator de amortecimento, observou-se que para o CLEPE, este parâmetro é ligeiramente superior ao do CC, sugerindo uma integridade estrutural adequada das lajes. Com base nos resultados obtidos, conclui-se que, para análises individuais de elementos de CLEPE sem fissuras, é recomendável adotar um valor médio para o fator de amortecimento de 0,5%, que se mostrou superior ao valor médio correspondente ao CC ensaiado, sem fissuras, de 0,4%. No entanto, para análises estruturais globais, os valores teóricos convencionais são mais apropriados. Embora a pesquisa forneça resultados sobre o comportamento dinâmico de lajes de CLEPE, ressalta-se a necessidade de estudos adicionais em condições de fissuração para uma compreensão mais abrangente do material em situações realistas.

Resumo em Inglês:

ABSTRACT The use of Lightweight Concrete with EPS Beads (LCBE) in structural slabs emerges as an economically attractive alternative to reduce the self-weight of reinforced concrete structures. However, the modification of the structural mass and the substitution of conventional coarse aggregate by EPS directly impact the dynamic properties of the structure. In this context, the objective of this study is to investigate the influence of replacing Conventional Concrete (CC) with LCBE on the dynamic properties of the structure, considering the significant decrease in mass and stiffness of the material. For the determination of dynamic parameters such as natural frequencies, modal deformations, and damping factors, experiments were conducted on cylindrical specimens and rectangular slabs using stochastic modal analysis methods and dynamic acoustic response tests. The results reveal clarity in modal deformations and a satisfactory approximation between experimental and numerical natural frequencies. Regarding the damping factor, it was observed that for LCBE, this parameter is slightly higher than that of CC, suggesting adequate structural integrity of the slabs. Based on the obtained results, it is concluded that for individual analyses of crack-free LCBE elements, it is recommended to adopt an average value for the damping factor of 0.5%, which proved to be higher than the corresponding average value for crack-free CC tested, of 0.4%. However, for global structural analyses, conventional theoretical values are more appropriate. Although the research provides results on the dynamic behavior of LCBE slabs, the need for additional studies under cracking conditions is emphasized for a more comprehensive understanding of the material in realistic situations.