| Abstract: |
The production of conventional concrete accounts for ∼8% of global CO₂ emissions through the energy-intensive production of ordinary Portland cement (OPC). Alternative environmentally friendly and more economically sustainable types of concrete have been developed, like the green concrete development using agricultural wastes materials such as rice husk ash (RHA), sugarcane bagasse ash (SCBA), bamboo leaf ash (BLA). An experimental study was conducted to evaluate the mechanical, durability and microstructural properties of green concrete mixes having partial replacement of OPC using RHA (10%, 15%, 20%), SCBA (5%, 10%, 15%) and binary blend of RHA+SCBA at four proportions (10%+5%, 10%+10%, 15%+5%, 15%+10%) at water to cementitious materials ratio of 0.45. Total 108 concrete cube and cylinder specimens were cast and tested for compressive strength (7, 28 and 90 days), split tensile strength, flexural strength, water absorption and rapid chloride penetration. The results reveals that optimal 28-day compressive strength of 43.8 MPa is achieved from the 15% RHA and 10% SCBA binary replacement (mix RS4), the increase were to level of 12.3% higher than the control mix and this eco-friendly concrete gave 18.4% lower of CO₂ emission and 10.6% lower material cost per cubic metre compared to the control mix. One-way ANOVA analysis with a significance limit of 0.05 for replacement type and level indicates highly significant levels of mechanical performance (F = 31.42, p < 0.001). Regression models (R² up to 0.988) as validated mix-design tools were used to optimise agricultural ash content. |
