Engineering Properties of Fly Ash and Rice Husk Ash-Based Geopolymer Concrete

Geopolymer concrete is sustainable concrete as they do not use cement as binding material. Rice husk ash which is a residue of rice is currently used as landfill and its effective disposal is a huge issue. Mixture design of fly ash and rice husk-based geopolymer concrete for M 25 grade of concrete was carried out. Effect of various parameters like amount of rice husk ash, molarity of sodium hydroxide, amount of alkaline solution, and amount of alkaline solution to cementitious material was studied in detail and its effect on compressive strength was evaluated. It was observed that increase in molarity beyond 12 M led to decrease in compressive strength while increase in alkaline solution increased compressive strength. Rice husk ash being coarse and porous in nature, beyond 5% inclusion without grinding led to decrease in compressive strength. It was observed that fly ash and rice husk ash-based geopolymer concrete has compressive strength of 30.5 MPa, flexural strength of 4.07 MPa, and split tensile strength of 3. 97 MPa. Detail microstructure analysis was also carried out.