CHARACTERIZATION OF BRAZILIAN CONSTRUCTION AND DEMOLITION WASTE COARSE RECYCLED AGGREGATE

摘要

This article aims to apply the combination of heavy media and hand sorting in representative samples of Brazilian CDW aggregates from two different recycling plants and to characterize relevant fractions by chemical, mineralogical and physical tests. Three national CDW coarse recycled aggregates were sampled, sieved, separated in four heavy media classes (d < 1.9; 1.9 < d < 2.2;2.2 < d < 2.5;d > 2.5 g/cm~3), sorted by hand sorting and chemically, mineralogically and physically characterized. The results show that Brazilian mixed coarse recycled aggregates are mainly constituted of silicates. The presence of Portland cement was secondary. All studied samples do not comply with RILEM aggregate specification for concrete > 50 MPa. In heavy media separation, tectosilicates (rocks and natural gravels) are separated when d > 2.5 g/cm~3. A mixture of tectosilicates, phyllosilicates and carbonates from cement-based and ceramic particles mainly composes the other heavy media classes. The hand sorting method sorts recycled aggregates only by its phase. As a result, cement-based and ceramic particles have significant physical aggregate property variability. Using both methods guarantee best results in terms of homogeneity of physical aggregate properties. For all studied samples, it was possible to establish a correlation between the amount of binders and the aggregate bulk specific gravities.