Performance evaluation of sustainable concrete incorporating cement-coated corn cob aggregate and rice husk ash

The increasing environmental impact of cement manufacturing and the extensive extraction of natural aggregates need an alternative for sustainable concrete production. This study evaluates the synergy of rice husk ash (RHA) and cement-coated corn cob aggregate (CCA) as partial replacements for cement and coarse aggregate to produce eco-friendly concrete. M30-grade concrete mixes were prepared using combined replacement levels of RHA (0–15%) and CCA (0–9%) in increments of 2.5% and 1.5%, respectively, and evaluated for their fresh, mechanical, durability, and sustainability properties. Increasing RHA and CCA reduced workability and dry unit weight (DUW); however, mixes up to 10% RHA + 6% CCA (optimum substitution) enhanced overall mechanical performance, specifically boosting compressive strength (CS) by 12–15% compared to conventional concrete (CC). Significant durability enhancement was observed, with reductions of approximately 30% in RCPT, 27% in permeability, and 32% in sorptivity at the optimum replacement level. A material cost-based analysis and emission factor approach were used to estimate cost and embodied CO₂, indicating up to 9–10% cost savings and 17–18% CO₂ reduction at the optimum mix compared to CC. These findings confirm that RHA-CCA concrete is a viable, eco-friendly alternative for structural applications, offering significant carbon reductions and technical reliability.