ABSTRACT Economic development based on cleaner industrial technologies has been increasingly studied in recent years. Cementitious composites reinforced with lignocellulosic fibers can be a sustainable alternative for use in engineering. The study aimed to evaluate the technological properties of cementitious composites produced from natural and industrial coconut fiber to compare the reinforcement with wood particles. Physical tests (density, water absorption, and thickness swelling) and mechanical tests (static bending) were carried out in four treatments, which varied the fiber and cement contents. It was found that treatment with natural coconut fiber had the lowest density value, 0.59 g/cm3, and treatment with industrial coconut fiber had the lowest water absorption value for the times and times of 2 and 24 h, 0.19, and 0.38%, respectively, and the treatment with wood particles, the highest values of modulus of elasticity and rupture, 1,897 MPa and 2.44 MPa. The study of the use of lignocellulosic materials as protection in cementitious composites is essential for applications in building constructions to reduce the environmental impacts generated by the generation of waste and use of non-renewable materials and to promote sustainable development.

RESUMO O concreto leve tem sido utilizado para fins estruturais e para a redução do peso próprio das estruturas de concreto. A utilização da argila expandida como agregado graúdo é economicamente viável na fabricação desses concretos devido à redução de massa específica que este tipo de agregado proporciona. Em busca de um desenvolvimento sustentável, a indústria da construção civil vem utilizando resíduos gerados em empresas do setor de rochas ornamentais como uma alternativa de minimizar os impactos ambientais. Assim, nesta pesquisa foram produzidos concretos leves com a incorporação do resíduo proveniente do corte de granito em substituição parcial ao agregado miúdo (areia), nas proporções de 5%, 10% e 15%. Foram produzidas uma mistura de referência do concreto leve utilizando-se argila expandida, areia e cimento, e misturas com substituição do agregado miúdo natural por porcentagens do resíduo do corte do granito, mantendo-se constante o fator água/cimento, a sílica ativa e o superplastificante. Os corpos de prova produzidos foram caracterizados por meio de ensaios físicos (determinação da absorção de água, índice de vazios e massa específica), ensaio de resistência mecânica (compressão axial) e durabilidade. As formulações realizadas apresentaram valores de massa específica e resistência à compressão compatíveis com o concreto leve estrutural. Com os resultados dos ensaios, concluiu-se que a substituição de 15% do resíduo foi a que apresentou maior resistência à compressão, massa específica satisfatória (menor que 2000 kg/m³) e melhor fator de eficiência. Adicionalmente, com relação à durabilidade do concreto, as formulações com a incorporação do resíduo de granito apresentaram-se mais resistentes ao ataque por sulfatos.

ABSTRACT Lightweight concrete has been used for structural purposes and to reduce the self-weight of concrete structures. The use of expanded clay as a coarse aggregate is economically viable in the manufacture of these concretes due to the reduction in specific mass that this type of aggregate provides. In search of sustainable development, the civil construction industry has been using waste generated by companies in the ornamental stone sector as an alternative to minimize environmental impacts. Thus, in this research, lightweight concrete was produced with the incorporation of waste from granite cutting in partial replacement of fine aggregate (sand), in proportions of 5%, 10% and 15%. A reference mixture of lightweight concrete was produced using expanded clay, sand and cement, and mixtures with replacement of the fine natural aggregate by percentages of waste from the cutting of the granite, keeping constant the water/cement factor, silica fume and the superplasticizer. The produced test specimens were characterized by physical tests (determination of water absorption, void index and specific mass), mechanical resistance test (axial compression) and durability. The formulations performed presented specific mass and compressive strength values compatible with structural lightweight concrete. With the results of the tests, it was concluded that the replacement of 15% of the residue was the one with the highest compressive strength, satisfactory specific mass (less than 2000 kg/m³) and the best efficiency factor. Additionally, with regard to the durability of concrete, the formulations with the incorporation of granite waste were more resistant to attack by sulfates.

Abstract: Lightweight concrete has as main characteristic its low density due to the incorporation of light materials such as expanded clay, or even the incorporation of air whose function is to reduce the density, characteristic of cellular concrete. In Aracaju city, there are companies that promote tire reconditioning, generating large amounts of waste dust. The aim of this work is to study the reuse of tire rubber waste in light concrete from expanded clay. An experimental program was developed for the analysis of these concretes, varying the percentage of 1%, 2.5% and 5% of the tire rubber waste to replace the natural fine aggregate and 100% replacing the natural coarse aggregate by expanded clay (50% of expanded clay C1506 and 50% of C2215). The materials (cement, sand, expanded clays and tire rubber waste) were characterized through tests of particle size analysis and unit mass. The hardened concrete was evaluated through mechanical tests of axial compression strength, modulus of elasticity and tensile strength by diametrical compression, physical tests of water absorption and specific mass, in addition to image analysis by scanning electron microscopy. The use of expanded clay with incorporation of 1% of tire rubber waste guaranteed better results in mechanical resistance, lower water absorption and greater specific mass than the mixtures with 2.5 and 5%, reaching values close to the reference concrete. Thus, the residue can be an alternative for reuse, avoiding disposal.

Resumen: El hormigón ligero tiene como característica principal su baja densidad debido a la incorporación de materiales ligeros como la arcilla expandida, o incluso la incorporación de aire cuya función es reducir la densidad, característica del hormigón celular. En la ciudad de Aracaju, existen empresas que promueven el reacondicionamiento de llantas, generando grandes cantidades de polvo de desecho. El objetivo de este trabajo es estudiar la reutilización de residuos de caucho de neumáticos en hormigón ligero a partir de arcilla expandida. Se desarrolló un programa experimental para el análisis de estos hormigones, variando el porcentaje de 1%, 2.5% y 5% de los residuos de caucho de llantas para reemplazar el agregado fino natural y el 100% de reemplazo del agregado grueso natural por arcilla expandida (50% de arcilla expandida C1506 y 50% de C2215). Los materiales (cemento, arena, arcillas expandidas y residuos de caucho de neumáticos) se caracterizaron mediante pruebas de análisis de tamaño de partícula y masa unitaria. El hormigón endurecido se evaluó mediante pruebas mecánicas de resistencia a compresión axial, módulo de elasticidad y resistencia a tracción por compresión diametral, pruebas físicas de absorción de agua y masa específica, además de análisis de imagen por microscopía electrónica de barrido. El uso de arcilla expandida con incorporación del 1% de residuos de caucho de neumáticos garantizó mejores resultados en resistencia mecánica, menor absorción de agua y mayor masa específica que las mezclas con 2,5 y 5%, alcanzando valores cercanos al hormigón de referencia. Por tanto, el residuo puede ser una alternativa de reutilización, evitando su eliminación.

RESUMO Os concretos leves podem ser utilizados na construção civil como isolamento térmico e acústico, cobrimento de lajes, produção de placas, entre outros. Produzidos a partir de argila expandida, que apresentam massa unitária entre 300 e 2000 kg/m3, os materiais garantem redução do peso de estruturas favorecendo a diminuição dos custos com as fundações. Neste trabalho, foi estudado o melhor arranjo granulométrico de argilas expandidas de granulometrias de diâmetro 22, 15 e 5 mm, com o fim de produzir placas de concreto com baixo peso específico e sem alteração da resistência mecânica à flexão em três pontos, em comparação as que são confeccionadas a partir de britas convencionais. As matérias-primas foram caracterizadas por meio da massa unitária, massa específica, absorção de água, análise granulométrica, análise química por fluorescência de raios X (FRX) e foram determinadas as fases presentes por difratometria de raios X-DRX. Em seguida, foi utilizado o diagrama triangular de Winkler com o intuito de obter as massas unitárias e os respectivos empacotamentos. Este diagrama é pouco difundido no segmento de construção civil e pode ser muito útil para realizar misturas de até três componentes e avaliar qualquer propriedade, definindo uma região ótima de trabalho. Foram escolhidos pontos do diagrama com diferentes massas unitárias, para produção de corpos de prova de concreto com argila expandida e com o agregado convencional. Os corpos de prova foram submetidos ao ensaio de resistência mecânica à flexão em três pontos e densidade aparente. Os resultados mostraram que houve redução de 30% a 50% no peso das peças, sem alteração da resistência mecânica nas formulações A e D. Vale ressaltar que a densidade e resistência mecânica das formulações A e D foram as maiores em relação às argilas expandidas, provavelmente devido ao menor abatimento apresentado além da elevada massa unitária mostrada no diagrama ternário.

ABSTRACT Lightweight concretes can be used in civil construction, such as thermal and acoustic insulation, slab cover, plate production and others. Produced from expanded clay, which have a unit mass between 300 and 2000 kg / m3, the materials guarantee a reduction of the weight of structures favoring the reduction of the costs with the foundations. In this work, the best granulometric arrangement of expanded clays of 22, 15 and 5 mm diameter granulometry was studied in order to produce concrete slabs with low specific gravity and with no change in mechanical resistance to flexural strength, compared to those made with from conventional crushers. The raw materials were characterized by means of unit mass, specific mass, water absorption, particle size analysis, chemical analysis and X-ray diffraction. Next, Winkler's triangular diagram was used in order to obtain the unit masses and The respective packaging. This diagram is not very widespread in the construction segment and can be very useful for mixing up to three components and evaluating any property, defining an optimum working region. The points of the diagram were chosen with different unit masses for the production of test specimens with expanded clay and with the conventional aggregate. The specimens were submitted to three - point flexural strength and apparent density test. The results showed that there was a reduction of 30% to 50% in the weight of the pieces, without altering the mechanical resistance in formulations A and D. It is worth mentioning that the density and mechanical strength of the formulations A and D were the largest in relation to the lightweigth, probably due to the smaller slump presented, besides the high unit mass presented in the ternary diagram.