Produção de concreto com resíduos sólidos de curtumes tipo “wet blue” a partir da substituição parcial de agregado miúdo
Data
2021-02-05
Autores
Canhada, João Carlos dos Santos
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A produção de couro é uma tecnologia que impulsiona a economia devido à sua versatilidade e durabilidade. No entanto, os resíduos gerados ao longo do processo podem se tornar classificados como tóxicos devido à elevada concentração de cromo, derivado do processo de curtimento, em que o agente curtente mais empregado no mercado é o cromo (Cr(III)). Neste trabalho, foram avaliados o efeito da incorporação das raspas de couro micronizada nas propriedades mecânicas e físicas do concreto, bem como a possibilidade de neutralização da toxicidade do cromo existente nesse resíduo. O agregado natural (areia) foi parcialmente substituído pela raspa de couro, na ordem de 5% e 10%. Para caracterizar as propriedades mecânicas (resistência à compressão, tração por compressão diametral), físicas (massa específica, índice de vazios e absorção de água) e morfológicas dos concretos, foram avaliadas amostras de 7, 14 e 28 dias. A lixiviação foi realizada para determinar quanto de cromo é liberado pelo compósito. Observou-se que a trabalhabilidade do concreto reduziu drasticamente à medida que a quantidade de resíduo era inserida, sendo assim, fez-se necessário a adição de um aditivo superplastificante para torná-lo trabalhável e viável. Para as propriedades físicas, o índice de vazios e absorção de água, ambos foram melhorados ao se adicionar o aditivo superplastificante. Os resultados da microscopia eletrônica de varredura indicaram a dispersão das fibras de couro na matriz de cimento. O ensaio de lixiviação demonstrou que a liberação de cromo é menor que 5µg/mL, valor estabelecido pela norma ABNT NBR 10.004/2004. Os resultados experimentais destacam a capacidade e potencialidade de utilização do concreto com raspas de couro, tanto como concreto estrutural ou não estrutural dentro da construção civil. Sendo assim, confeccionou-se as calçadas do novo laboratório de resíduos da FCT/UNESP – Presidente Prudente com 3 m³ do C10A traço 2.
Leather production is a technology that propels the economy due to its versatility and durability. However, the waste generated during the process might be classified as toxic due to the high concentration of chromium derived from the tanning process where the tanning agent most used in the market is the chromium (Cr+3). Hence, in this project, the effects on the mechanical and physical properties of the concrete composite with leather shavings incorporated in it were evaluated, as well as the possibility of neutralizing the toxicity of the chromium in this residue. The natural aggregate was partially replaced by leather scraps, in the order of 5% and 10%. To characterize the mechanical, physical and morphological properties of the concrete, samples of 7, 14 and 28 days were analyzed. Leaching test was performed to determine the efficiency of chromium encapsulation in the cement matrix. It was noted that the workability of the concrete reduced significantly as the dosage rate of the leather shavings increased, therefore, it was necessary to add the superplasticizer additive to make it workable and viable. It was observed a decrease in the mechanical properties of the samples with and without additives. For the physical properties, both the void ratio and water absorption were improved by adding the superplasticizer additive. The results of the scanning electron microscopy indicated a satisfactory interaction between the leather fibers and the cement matrix. The leaching test demonstrated that the release of chromium is lower than 5µg/mL, value established by the standard ABNT NBR 10.004/2004. The experimental results highlight the capacity and potential of using concrete with leather scraps, both as structural or non-structural concrete within civil construction. Thus, 3 m³ of the new composite were used in the sidewalk of the Laboratory of Residues of FCT -UNESP – Presidente Prudente.
Leather production is a technology that propels the economy due to its versatility and durability. However, the waste generated during the process might be classified as toxic due to the high concentration of chromium derived from the tanning process where the tanning agent most used in the market is the chromium (Cr+3). Hence, in this project, the effects on the mechanical and physical properties of the concrete composite with leather shavings incorporated in it were evaluated, as well as the possibility of neutralizing the toxicity of the chromium in this residue. The natural aggregate was partially replaced by leather scraps, in the order of 5% and 10%. To characterize the mechanical, physical and morphological properties of the concrete, samples of 7, 14 and 28 days were analyzed. Leaching test was performed to determine the efficiency of chromium encapsulation in the cement matrix. It was noted that the workability of the concrete reduced significantly as the dosage rate of the leather shavings increased, therefore, it was necessary to add the superplasticizer additive to make it workable and viable. It was observed a decrease in the mechanical properties of the samples with and without additives. For the physical properties, both the void ratio and water absorption were improved by adding the superplasticizer additive. The results of the scanning electron microscopy indicated a satisfactory interaction between the leather fibers and the cement matrix. The leaching test demonstrated that the release of chromium is lower than 5µg/mL, value established by the standard ABNT NBR 10.004/2004. The experimental results highlight the capacity and potential of using concrete with leather scraps, both as structural or non-structural concrete within civil construction. Thus, 3 m³ of the new composite were used in the sidewalk of the Laboratory of Residues of FCT -UNESP – Presidente Prudente.
Descrição
Palavras-chave
Raspa de couro, Concreto, Cromo, Agregado natural, Leather waste, Concrete, Chromium, Natural aggregate