REAÇÃO ÁLCALI-AGREGADO PELO MÉTODO ACELERADO EM BARRAS DE ARGAMASSA: Avaliação de agregados de gnaisses provenientes do município de Varginha-MG

Abstract

There are pathologies that occur in reinforced concrete structures that over the years have been studied and questioned investigative methods in order to find out their causes and how to inhibit them to prevent possible disasters. The main objective of the research is to determine the alkali-aggregate reaction potential in gneiss concrete mixed with CP III cement and CP V-ARI cement. The alkali-aggregate reaction (RAA) is an expansive phenomenon that occurs in various concrete structures that experience frequent humidity conditions. The product formed is an expansive gel that causes cracking processes and differential displacements in concrete structures. Currently, there are several researchers who have been studying the various ways to diagnose the presence of AAR in structures, to previously assess the reactive potential of aggregates used in general concrete structure works. The methods commonly used in the assessment of AAR involve laboratory tests standardized by NBR 15577 (ABNT, 2018). The methodology used in this research was the accelerated method in mortar bars according to ABNT NBR 15577-4: 2018. Nine mortar bars were made, three bars using CPIII cement, three using CPV-ARI and three using modified CPV-ARI, but with smaller aggregate particle size. The results presented showed that only the modified CPV-ARI mortar bars gave a significant degree of reactivity to the others.