Enhancing the Sustainability and Performance of Concrete through the Integration of Industrial and Agricultural By-Products: A Comprehensive Study

The construction industry, particularly the production of Portland cement, is a significant contributor to global carbon dioxide emissions and natural resource depletion. This study investigates the feasibility and effectiveness of partially replacing cement with two widely available by-products: Fly Ash (FA), a industrial waste from coal combustion, and Rice Husk Ash (RHA), an agricultural residue. The primary objective is to develop concrete mixes that not only reduce the environmental footprint but also maintain or enhance the mechanical and durability properties. Experimental programs were designed to cast and test concrete specimens with varying replacement levels of cement with FA (15%, 25%, 35%) and RHA (5%, 10%, 15%). The key parameters evaluated include workability (slump test), compressive strength at 7, 28, and 56 days, split tensile strength, water absorption, and resistance to sulphate attack. The results indicate that a ternary blend of 70% OPC, 25% FA, and 5% RHA yields an optimal balance. This mix achieved a 28-day compressive strength comparable to the control (0% replacement) while demonstrating a 22% reduction in water absorption and superior resistance to sulphate exposure. Microstructural analysis via Scanning Electron Microscopy (SEM) revealed a denser matrix with reduced calcium hydroxide content, explaining the improved durability. The study concludes that the synergistic use of FA and RHA presents a viable, eco-friendly pathway for producing high-performance, sustainable concrete, contributing directly to the circular economy and greener construction practices.