Avaliação da reação álcali-sílica com a utilização de uma blenda de sílica de casca de arroz e cinza volante

Abstract

The present work had as main objective the determination of the Portland cement substitution contents by a mixture of rice husk silica (SCA) and fly ash (CV), which were able to mitigate the deleterious effects of this pathology, within tolerable limits . As a result of this, a research program was established that initially includes as a complementary analysis the determination of the mechanical behavior of these mixtures by the simple compression tests and flexural tensile tests, (ABNT NBR 13279/2005). In a second, the analysis of the expansions of the mortar bars submitted to the accelerated test according to the norm (ABNT NBR 15577-4/2009) was sought. In addition, we sought to determine the mass loss from the displacements of the bars subjected to the accelerated test. For the execution of these tests, a reference mixture, unused substitutions and four mixtures with bulk substitutions of: 3% SCA and 10% CV were cast; 3% SCA and 20% CV; 10% SCA and 10% CV; 10% SCA and 20% CV. The correlation between the obtained results and the substitution levels, evidenced the efficiency of the use of fly ash in the combat to the expansions, as well as, in the improvement of the mechanical performance. On the other hand, it was verified that the use of silica of rice husk in these contents tends to favor the phenomenon of alkalisilica reaction, determining the reactive character of pozolana.