Estudo do potencial do cimento supersulfatado na mitigação da reação álcali agregado pelo método acelerado das barras de argamassa

Abstract

The RAA is an expansive reaction between alkaline ions, mainly from clinker, and reactive minerals present in the aggregates. The alumina in the cement forms a protective film that surrounds the aggregate and makes it difficult for reactive minerals to dissolve and react with the alkaline ions that form the expansive gels, the presence of calcium is a factor that aggravates the gels' expansive potential. Based on this, supersulfated cement (CSS), containing high alumina and low calcium content, presents itself as a possible solution for RAA, thus, the objective of this work was to evaluate the behavior of CSS when subjected to contact with a reactive aggregate found in the Pato Branco-PR region, analyzing the influence of calcium and alumina content in the cement. For this, mortar bars were molded for the expansion test by the accelerated method, having as reference mortars composed of Portland cement CP IV and CPV, known for having, respectively, a good and a bad performance when submitted to RAA. The pieces underwent mechanical resistance analysis, visual, absorption and microstructural analysis, to identify the possible formation of the expanding gel. From the results, it was observed that the CSS, cement with the highest alumina content and the lowest calcium content, had the greatest effectiveness in mitigating the RAA, being effective in controlling expansion and loss of mechanical strength.