Resumen El objetivo de este estudio fue proponer una correlación para los parámetros hidráulicos del concreto permeable (CoPe). Para esto, se utilizaron 3 agregados de residuos de construcción civil y 1 agregado de basalto como referencia para producir CoPe. La relación 1: 3.26 (cemento: agregado) se trabajó en todas las mezclas, una relación a/c de 0.34. Se realizaron pruebas de resistencia a la compresión y resistencia a la flexión para caracterizar mecánicamente el concreto producido y verificar el cumplimiento con los estándares ACI 522R-10, NBR 16416 (2015) y VTT-R-080225-13. También se llevaron a cabo pruebas de porosidad y permeabilidad a carga constante para estudiar las propiedades hidráulicas del material. Los resultados indican que es factible producir concreto permeable con agregados sostenibles que cumplan con los estándares y que se podría usar en la construcción de calzadas. Por otro lado, se propone una correlación de permeabilidad y porosidad que involucra las leyes de Bernoulli y Darcy y establece las condiciones de contorno en las que funcionan estas dos propiedades, teniendo como conclusión una ecuación exponencial que caracteriza la eficiencia hidráulica de los canales internos del material relacionado. A la interconexión de poros. Al realizar la regresión no lineal, la ecuación se ajusta a los resultados encontrados y se ajusta a lo que se encuentra en la literatura, siendo una herramienta excelente para identificar la eficiencia hidráulica del material.

Abstract The aim of this study was to propose a correlation for the hydraulic parameters of pervious concrete (PC). Thus, three aggregates from civil construction waste and one basalt aggregate (reference) were used to produce PC. The ratio c/a (cement: aggregate) 1:3.26 and a w/c ratio of 0.34 were used in all mixtures. Compressive and flexure tensile strength tests were performed to mechanically characterize the mixtures produced, whereas porosity and constant head permeability tests were also carried out to assess the material hydraulic properties. Firstly, the experimental results were compared with the requirements established in international guidelines (ACI 522R-10, NBR 16416 (2015) and VTT-R-080225-13). The results complied with the guidelines indicating it is feasible to produce pervious concretes with the sustainable aggregates used in the study in low structural applications such as walkways. On the other hand, a correlation between permeability and porosity was proposed based on Darcy’s and Bernoulli’s laws. The proposed equation, obtained by means of a non-linear regression, is an exponential equation that characterizes the hydraulic efficiency of the internal channels of the material considering the pores interconnection. The correlation between porosity and permeability was finally validated using results from the literature showing the same trend found in laboratory, and therefore it was demonstrated that the proposed correlation in an efficient tool to predict the hydraulic efficiency of pervious concrete.

Resumen Este estudio evaluó la posibilidad de usar Ceniza de Madera de Eucalipto (CME) de hornos de aviarios como un aditivo mineral en la fabricación de concreto. La ceniza fue pasada por el tamiz número 100 y se adiciono a la mezcla en la proporción 5, 10, 15 y 20% de la masa del cemento. El análisis físico reveló que la CME tiene una masa específica mayor que otros residuos de naturaleza orgánica y su área superficial específica BET no es suficiente para mejorar sus efectos filler y/o puzolánico. Químicamente, el residuo presentó un bajo porcentaje de materia orgánica y un IAP inferior al mínimo requerido por la norma brasileña. La CME interfirió en los tiempos de fraguado del cemento, aumentándolo, mientras la FTIR reveló la presencia de enlaces de silicio-oxígeno y carbonato de calcio. El aditivo comprometió el rendimiento mecánico de los concretos, concluyéndose que el procedimiento de tamizado de la CME solo no es suficiente para su uso como un aditivo mineral.

Abstract This study evaluated the possibility of using in natura Eucalyptus Wood Ash (EWA) from aviary furnaces as a mineral admixture in concrete. The ash was 100 mesh-sieved and added to the mix in 5, 10, 15 and 20% of the cement bulk. Physical analysis unveiled that EWA has a specific gravity higher than other organic originated residues, whereas its BET specific surface area is not enough to enhance its filler and/or pozzolanic effects. Chemically, the residue presented a low organic matter rate and a SAI below the minimum required by the Brazilian standards. EWA interfered in the times of cement set, increasing them, while FTIR unveiled mainly the presence of calcium carbonate bonds. The admixture compromised the concretes mechanical performance, leading to the conclusion that the sieving procedure of EWA alone is not enough do admit its usage as a mineral admixture.

Resumen Este estudio tiene como objetivo analizar el desempeño de dos composiciones de hormigón con adición de esporas de B. sutilis con relación a su capacidad de relleno de fisuras durante el periodo de cura, evaluando la influencia de la adición en la resistencia a compresión. Para ello han sido estudiadas seis composiciones de hormigón, divididas en dos dosificaciones: 1:1:2 y 1:2:3 (cemento: árido fino: grava) en peso, con relación a/c de 0,33 y 0,45. Para cada una de las mezclas se utilizaran concentraciones de 0, 0.3x108 or 1.2x108 de esporas de B. sutilis/mL. Los resultados obtenidos han demostrado que todas las muestras con adición de esporas presentaron precipitación de cristales, posiblemente carbonato de calcio, que fue visualizado en las fisuras. Más estudios microestructurales deberán ser realizados para comprobar que de hecho ocurrió el relleno de las fisuras. La resistencia a compresión presentó resultados satisfactorios, pues no hubo diferencias significativas en relación al hormigón de referencia, a nivel de 5% de probabilidad.

Abstract This study aimed to analyze the performance of two concrete mixtures with the addition of B. subtilis spores regarding their capacity of filling cracks during the curing time, evaluating whether the addition can influence the compressive strength of the concrete. For so, six concrete mixtures were studied divided in two mix compositions: 1:1:2 and 1:2:3 (cement: sand: gravel) with w/c of 0.33 and 0.45, respectively. For each composition were added concentrations of 0, 0.3x108 or 1.2x108 of B. subtilis spores/mL. The results showed that all the samples with spores addition presented crystals precipitation, possibly calcium carbonate, that visually filled the cracks. However, more studies of microstructural analysis should be conducted to prove that the cracks were closed. The compressive strength presented satisfactory results, because the addition of 1.2x108 spores/mL did not present significant differences in compressive strength at probability level of 5%, when compared to the reference concrete.

RESUMO A incorporação de nanossílica vem sendo estudada como uma alternativa para melhorar as características dos materiais cimentícios, pois tende a aumentar as reações pozolânicas e preencher os espaços intersticiais, diminuindo a porosidade e melhorando a resistência mecânica. Neste contexto, o presente estudo teve como objetivo avaliar o comportamento mecânico e as características microestruturais de três compósitos cimentícios: um de referência e dois contendo diferentes teores de nanossílica dispersas em policarboxilato (NDP), de 0,2 e 0,4%, em relação à massa do cimento. O comportamento mecânico foi avaliado mediante o ensaio de resistência à compressão e resistência à tração por compressão diametral. Além disso, foram realizados ensaios de absorção de água e análise microestrutural em Microscópio Eletrônico de Varredura (MEV). A partir da análise dos resultados, verificou-se que a adição de NDP melhorou as propriedades mecânicas e as características microestruturais dos compósitos cimentícios. Sendo que o compósito contendo o maior teor de NDP (0,4%) obteve melhores resultados aos 28 dias, apresentando um aumento de 55% na resistência à compressão, 79% na resistência à tração por compressão diametral e diminuindo em 40% a absorção de água, em relação à referência, possivelmente pela atuação da NDP. Porém, ao analisar a incorporação dos dois teores de NDP (0,2 e 0,4%), se verificou que ao dobrar o teor não houve uma melhora significativa da resistência à compressão, pois a incorporação de 0,2% de NDP aumentou a resistência à compressão em 53% em relação à referência. Quanto à análise microestrutural em MEV, verificou-se um refinamento da microestrutura a partir da incorporação de NDP, mas não foram visualizadas diferenças entre os dois teores incorporados.

ABSTRACT The incorporation of the nanosilica has been studied as an alternative to improve the characteristics of cementitious materials because tends to increase the pozzolanic reactions and fill the interstitial spaces, decreasing the porosity and improving the compressive strength. In this context, the present study has the goal to evaluate the mechanical behavior and the microstructural characteristics of three cementitious composites: the reference e two with different levels of nanosilica dispersed in polycarboxylate (NDP), 0.2 and 0.4%, in relation to the cement mass. The mechanical behavior was evaluated through the compressive strength test and tensile test (Brazilian denomination). Furthermore, were done water absorption tests and microstructural analysis by Scanning Electron Microscope (SEM). From the analysis of the results, it was verified that the addition of NDP improved the mechanical properties and the microstructural characteristics of cementitious composites. The NDP content (0.4%) showed better results at 28 days, presenting a 55% increase in compressive strength, 79% tensile test and a 40% decrease in the absorption of water, in relation to the reference, possibly through the NDPs performance. However, when analyzing the incorporation of the two NDP contents, it was verified that when the content was doubled there was no significant improvement in the compressive strength, since the incorporation of 0.2% of NDP increased the compressive strength in 53% in relation to the reference. As for the microstructural analysis, a refinement of the structure was verified from the incorporation of NDP but no differences between the two incorporation was visualized.

Resumen Este estudio tiene como objetivo verificar el potencial de uso del CBCA como sustitución parcial del cemento Portland. Por lo tanto, la campaña experimental fue dividida dos etapas; En la primera, se realizaron análisis mineralógicos y químicos con dos muestras de ceniza, crudas y calcinadas a una temperatura de 600°C durante 6h. En la segunda etapa, se observó que las cenizas calcinadas presentaban una mayor cantidad de material en estado amorfo, lo que posiblemente hizo que el material fuera el más reactivo. Por esta razón, sólo la ceniza calcinada se molió durante 1 y 2h. Adicionalmente estas muestras fueron estudiadas para verificar el índice de actividad puzolánica y la resistencia a la compresión, evaluando la sustitución de cemento Portland en proporciones de 10, 20 y 30% por SCBA. Los resultados mostraron un incremento demostrado que tanto la ceniza in-natura como la ceniza calcinada deben ser sometidas a un proceso de molienda para presentar actividad puzolánica.

Abstract This study aimed to verify the SCBA's potential use as a partial replacement of Portland cement. Therefore, the experiment was divided in two stages; in the first, mineralogical and chemical analyses were performed with two samples of ash, in-natura and calcined at a temperature of 600°C for 6h. After these analyzes, it was observed that the calcined ash presented a greater tendency of material in the amorphous state, which possibly made the material the most reactive. For this reason, only the calcined ash was ground for 1 and 2h. These samples were further studied in order to check the pozzolanic activity index and the compressive strength, evaluating the replacement of 10, 20 and 30% Portland cement by ground SCBA. The results showed an increase in the pozzolanic activity index only in samples of calcined and ground SCBA, showing that calcined ash must undergo a grinding process to present pozzolanic activity.