Rheological behavior study of plastic shrinkage and cracking of self-compacting concrete mortars

Resumo

This paper investigated the influence of the amount of superplasticizer and mineral adding - silica fume and basaltic filer - in plastic shrinkage and cracking of self-compacting concrete (SCC) mortars. Initially analysis was performed of the rheological behavior of cement paste and mortars phases of the compositions of SCC, with respect to the incorporation of mineral additions of different reactivity, either as to optimum levels of addition, whether the content of superplasticizer to be added to the mixture. Then we were measured deformations of mortars by the effect of shrinkage and evaluation of cracking, both in the fresh state. On plastic shrinkage, the composition with silica fume showed superior results, independent of wind and superplasticizer content, relative to the composition with addition of basalt filler. However, the same was not observed for vertical plastic deformation, only in the tests with imposed ventilation, the composition with silica fume showed superior results. The cracking at early ages resulted in higher fissured areas for the silica fume composition, also independent of the wind and superplasticizer content. The effect of the rheological behavior of the compositions on the plastic shrinkage and cracking showed with the fall of tensions flow occurs decrease these effects, confirmed by analysis of capillary pressures of mortars tested, which was observed from the earliest ages.