Efeito da substituição parcial do cimento por adições minerais na resistência à corrosão de concretos por ácidos orgânicos

Abstract

The development of new research to improve the understanding of the mechanisms of degradation of cementitious matrices in aggressive environments, together with changes in the composition and properties of conventional concrete, are essential to obtain concrete more resistant to degradation. Portland cement compositions with mineral additions are a possibility to produce more durable concretes. Additions can act as supplementary cementitious materials and as fillers. They reduce concrete porosity and consequently increase strength. In this context, this study investigated the durability of concretes containing two fine rock powders from the Serra Geral Formation (SGF) and rice husk ash, partially replacing cement Portland when exposed to organic acids. Fine rock powders and rice husk ash are waste materials commonly found in the environment and organic acids are highly aggressive to cement matrix. Four types of concrete were manufactured and immersed in acetic acid (AA) and lactic acid (LA) solutions. Compressive strength and corrosion resistance measurements were used to compare the performance of the three modified concretes with the reference concrete. The concretes with mineral additions exhibited superior corrosion resistance, evidenced by lower mass loss compared to the reference concrete. The residual compressive strength was related to the CaO content in the binder, as the AA and LA strength increased with decreasing CaO content in the binder. Therefore, based on the results of this study, it can be concluded that the concretes containing the mineral additions have greater durability than conventional Portland cement concrete. Finally, this study suggests that using waste materials, of local origin, as mineral additions can increase the durability of structures exposed to organic acids, in addition to contributing to the reduction of CO2 emissions and construction costs. [resumo fornecido pelo autor]