Characterization of Brazilian construction and demolition waste coarse recycled aggregate

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; 1.92.5 g/cm³), 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/cm³. 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.