Applied Mineralogy characterization of construction and demolition waste from Brazilian recycling plants

Three representative samples of construction and demolition waste recycled as aggregates were
taken from two different Brazilian recycling plants. The samples were fractioned by sink-and-float and
sieving techniques. The chemical composition, the main mineralogical phases and physical characteristics
such as bulk specific gravity of these fractions were determined. The applied mineralogy characterization of
CDW from Brazilian recycling plants allows to conclude that the studied recycled aggregates are essentially
constituted by silicates and carbonates; hydrated cement-based phases were not detected. They do not differ,
in majority, from origin (Itaquera and Vinhedo) or classes (Red and Grey). Phyllosilicates from clays were
detected in the size fraction bellow 0.15 mm. Tectosilicates from natural stones and sand used in construction
were found in the heaviest sink product (d>2.5 g/cm³). The binder content is correlated with SiO2 grades to
sink-float products. Mass distributions for sink-float products from individual size fraction indicate distinct
behavior due to the liberation of silicates. Physical properties of the attained products indicate that a gravity
concentration would allow producing a recycled aggregate for use both in structural concrete as well as in
high strength concrete.