Development of modified recycled aggregate for the production of sustainable concrete

Abstract

This paper deals with the treatment methods of recycled aggregate (RA) for its high water absorption which is due to the old mortar and micro-cracks on the surface of the recycled aggregate. Geopolymer paste which is made using class C & F fly ash are used for coating the recycled aggregate in order to reduce the water absorption (WA). The parameters which influence the coating of RA are fly ash content, molarity of alkaline solution, Liquid alkaline to ash ratio (LA/ash). The effect of each parameter on coating RA are analysed using Response surface methodology. It is observed that all the parameters has influenced the water absorption property of RA. LA/ash ratio depends on the molarity of the alkaline solution in reducing the WA of recycled aggregate. Coating of recycled aggregate with class C fly ash performed better than class F and uncoated recycled aggregate concrete. The optimal content of fly ash content, LA/ash ratio and molarity of solution are arrived using the statistical analysis are 4%, 0.35 and 9M respectively.