Shear strength and microstructural investigation on high-volume fly ash self-compacting concrete containing recycled concrete aggregates and coal bottom ash

Abstract

This article presents the experimental outcomes of the shear strength and microstructural characteristics of high-volume fly ash self-compacting concrete (HVFYA-SCC) containing recycled concrete aggregates and coal bottom ash as partial replacements for natural coarse aggregates and natural fine aggregates. A total of ten numbers of mixes were produced, including HVFYA-SCC made without recycled concrete aggregates and coal bottom ash (as control) along with HVFYA-SCC mixes made with recycled concrete aggregates (from 25% to 50%) and coal bottom ash (from 10% to 30%). The compressive and shear strength of the HVFYA-SCC mixes were improved by 7% and 4%, respectively, with the incorporation of 20% coal bottom ash and 25% recycled concrete aggregates after 120 days of curing. On the other hand, scanning electron microscopic analysis revealed that incorporating coal bottom ash exhibited the pozzolanic reactions with fly ash densified the binder-aggregate matrix of the resulting HVFYA-SCC.