Potencialidade do uso de Cinza de Casca de Arroz em Blocos de Concreto de Alvenaria Estrutural: Segundo NBR 6136.

Abstract

Agribusiness generates, annually, a significant quantity of food consumption products. Among the largest cereal crops are rice, wheat, soybeans and corn. During processing and industrialization, waste is generated, which in the case of rice is its husk. According to IBGE, Rio Grande do Sul is the largest rice producer, with 67.8% of the national production. Rice bark, according to NBR 10004 (ABNT, 2004), is a waste of class II.a, ie not inert and not hazardous to human health and the environment. However, when it is incinerated indoors (eg boilers and ovens), they result in highly polluting ash, releasing harmful gases that contribute to global warming. In order to contribute to the use of this residue, rice husk ash (CCA), this work had as objective to evaluate the potential of its use, in partial replacement of the binder, in concrete blocks. The evaluated requirements, specified by NBR 6136 (ABNT, 2014), were: simple compression strength, water absorption and dimensional analysis. The tests were performed according to NBR 12118 (ABNT, 2014) and the experimental program was divided into two stages: 1. block production with Portland cement (CP) CPII (Portland cement composite), CPIV (pozzolanic Portland cement) And CPVARI (Portland cement of initial high strength), for three families of traces (1: 6, 1: 8 and 1:10 - cement: aggregate); 2. production of the blocks with two types of cement (CPIV and CPVARI) and three levels of replacement of the same by CCA: 0, without substitution (reference) 5%; 10% and 15%. The results demonstrated that the proportion of 15% greatly reduces the compressive strength and its use with structural function is not indicated. The contents of 5 and 10% presented values lower than the reference, however, the CPVARI still maintained the structural function of the blocks. In the absorption results, CPVARI had better behavior. The second step of the research demonstrated that increasing the amount of rice hull ash provided increased absorption and decreased compressive strength, regardless of the type of cement. However, the results indicated that the partial substitution of different binders by CCA resulted in a material that meets the requirements of the Brazilian standards, and which provides a use with a sustainable bias to a residue.