Microstructural Characterization of Fine Recycled Aggregates by Sem-Mla

Abstract

Cement paste from previous construction projects is responsible for increasing the porosity of recycled aggregates and lowering their mechanical properties. The characterization of these products is fundamental for guiding mineral processing, though there are few established procedures. The scope of this study involved the technological characterization of fine aggregates produced from construction and demolition waste with the intention of assessing the associations and liberation of the main phases. The experiment involved heavy liquid separations, chemical and mineralogical analyses and scanning electron microscopy mineral liberation analysis (SEM-MLA) image analysis. The results confirmed that recycled sand is composed of a high content of low-porosity particles (high density) with low attached cement paste content. The main phases are tectosilicates, carbonates, phyllosilicate, mafic minerals and cement paste. The method proved to be a valuable tool for assessing the cement paste content and phase liberation; the attained results are consistent with mineral separations.