Influence of Metakaolin on Chemical Resistance of Low Calcium Fly Ash Based Geopolymer Concrete

Abstract

The study on cementless concrete is one of the most trending topics in the construction industry. This paper will give an inclusive on the effect of metakaolin on developing a low calcium fly ash (FA) based geopolymer concrete (GPC). Nine mixes were prepared with 30% and 50% replacement of low calcium FA with metakaolin, and molarity (8M, 12M and 16M) of alkaline activator (NaOH). Experiments were conducted on weight loss, residual compressive strength and Ultrasonic pulse velocity (UPV) of the GPC mixes. The experimental results indicated that workability of the mixes reduces with increasing percentage of metakaolin in comparison to the controlled GPC mix (100% low calcium FA). The compressive and tensile strength of geopolymer concrete mix with increasing molarity of NaOH solution and 30 - 50% replacement of fly ash with metakaolin was observed to be enhanced by 10 - 12% and 28 - 34% at 28 and 90 days respectively. The acid resistance values in terms of weight loss, compressive strength and quality of the specimens with 50% metakaolin substitution cured in H2SO4 solution for 56 days with different molarity was higher as compare to the control mixes. Thus, presence of metakaolin in the low calcium based GPC helps in resisting the aggressive chemical ingress in the concrete.