Effect of RHA on High-Strength Geopolymer Mortar

Cement is a binder that has been widely used as a construction material for its stability and strength. But production of cement emits CO2 gas which causes an environmental threat. To overcome this issue, cement is being replaced by geopolymer which is an eco-friendly material that causes less environmental impact. This study focuses on achieving high-strength RHA-based geopolymer mortar. Binders used are Rice Husk Ash (RHA) and Ground Granulated Blast Furnace Slag (GGBS), which are by-products of industrial steel and agriculture wastes, respectively. Various proportions of RHA (5%, 10%, 15%, 20%) were used to replace GGBS. Sodium hydroxide (NaOH) and Sodium silicate (Na2SiO3) were mixed in the ratio of 1:2. Alkaline activator to binder ratio was varied as 0.45 and 0.5. Mortar cubes of size 70.6 × 70.6 × 70.6 mm were cast and was subjected to ambient and oven curing. Specimens were kept in oven at 60 °C for 6 h. The compression strength test was performed at 7th and 28th day. From this study, the maximum compressive strength of 86.54 N/mm2 was achieved at 28th day when GGBS is replaced by 10% RHA mix (G90R10), under oven curing with alkali activator to binder ratio of 0.45. It show that oven cured geopolymer mortar gave better compressive strength compared to ambient curing.