Physical, mechanical and microscopic characterization of cold bonded fly ash lightweight aggregates

Abstract

This study presents the results of the different tests carried out on fly ash lightweight aggregates produced with three different kinds of binders: Lime, Portland cement and Pozzolan Portland cement. The elaboration process used for the aggregates consisted in an agglomeration system by agitation under cold bonded hardening conditions. The tests carried out were a physical characterization of the aggregates, the determination of mechanical properties with a crushing test and, finally, the study of the microstructure of the aggregates with scanning electron microscopy (SEM) and dispersive energy X ray (EDX). From the point of view of mechanical strength, the results indicate that the best kind of aggregate is the one made with a 5% Pozzolan Portland cement. This result was confirmed by the microstructure analysis, which shows that this kind of aggregate presents the highest hydration speed.