Microstructural, mechanical, and durability assessment of sustainable geopolymers synthesized using rice husk ash, a byproduct of the rice industry

Rice cultivation generates substantial quantities of rice husk, which, upon combustion, produces rice husk ash (RHA) – an abundant, silica-rich agricultural byproduct. While RHA presents environmental disposal challenges, its high amorphous silica content offers potential for sustainable material applications. This study investigates the incorporation of high-volume RHA into geopolymer bricks, aiming to develop eco-friendly construction materials. Utilizing response surface methodology, the mix parameters, including RHA content, alkali ratio, and curing conditions, were optimized. The results demonstrated that geopolymer bricks containing up to 40% RHA achieve compressive strengths meeting ASTM standards and exhibit enhanced acid resistance compared to traditional cement-based mixtures. Microstructural analyses confirm the formation of durable phases such as mullite and albite. This work highlights a viable pathway for valorizing agricultural waste into sustainable building materials, contributing to circular economy practices and carbon footprint reduction.