Desempenho reológico e mecânico do microconcreto autoadensável com o uso de RCD reforçado com fibras metálicas

Abstract

The aim of this research was to analyze the rheological performance in the fresh state and the mechanical performance in the hardened state of a self-compacting microconcrete with total replacement of natural aggregate with CDW, as well as a mixture with 100% CDW aggregate and with the inclusion of metallic fibers, compared to a reference concrete without metallic fibers. To characterize the fluidity, plastic viscosity and passing ability of the self-compacting microconcrete in the fresh state, rheological tests were carried out using the Abrams cone, V funnel and L box. For the mechanical tests, cubic specimens with dimensions of 100x100 mm and plates with dimensions of 12x100x400 mm were cast. Three mixtures were made: the reference mixture called AN, the mixture replacing natural sand with CDW sand called ARCD and, finally, the mixture replacing natural sand with CDW sand and including fibers called ARCDF. The results obtained from the rheological tests in the fresh state were consistent with the characteristics of this type of microconcrete. The spread values obtained were greater than 550 mm. All the microconcretes studied showed good viscosity without exudation or segregation. The axial compressive strength results for the mixes using CDW were lower compared to the mixes using natural sand. In the results obtained for the four-point flexural tensile strength, although there was an increase in the average tensile strength, the statistical analysis with a probability of 95% shows that there is no significant difference between the mixtures studied. The cracking process was evaluated using image correlations, using the GOM Correlate ® software. In addition to the analysis of the dispersion of the metal fibers in a cubic sample and a plate subjected to X-ray images. The results obtained showed that there is a relationship between the methods used, and for the mixtures containing fibers it was possible to evaluate the high dispersion of the tensile stress x displacement curves obtained.