Caracterização e composição de agregados reciclados para obtenção de concreto autoadensável leve reciclado com fins estruturais

Abstract

The use of recycled aggregate in the production of self-compactig concrete (SCC) is relatively recent. Few studies have been developed, but, there are numerous advantages in its application. The recycled lightweight self-compacting concrete (RLSCC) offers several advantages of SCC, due to the self-compacting properties, it absorbs construction residues, in the use as recycled aggregates, and the lightness due to the smaller specific mass of the recycled aggregates, it promotes the reduction of the loads due to the own weight . However, studies carried out in concrete with recycled aggregates (RA) have shown to be very complex due to the characteristics of these aggregates, such as: high porosity, high water absorption, irregular shape, rough surface, etc. These characteristics tend to lead to mixtures with less workable and lower mechanical strength. In this way, the study had as objective to obtaining the RLSCC, separate the process in two steps: aggregates and mortar. Where, the characterization of the RA is the way to understand its characteristics and the limitations that it will impose in the mixture of concrete. The study of mortars, to verify a composition with the best parameters of fluidity and rheological, since the difficulty faced by researchers in obtaining workable mixtures. Thus, it was verified that the standardized characterization methodologies, for natural aggregates, face some difficulties in their application in recycled aggregates, rendering them inefficient. The characteristics of the recycled aggregate could be attenuated with a composition study, reaching very workable mortars, with low yield stress and moderate viscosity. The SCC was obtained through a study of maximum content of recycled coarse aggregate, through concrete tests. The obtained concrete presented compression strength of 30 MPa and apparent specific mass of 2000 kg/m³, classifying it as concrete of structural application and light.