Mechanical and Durability Performance of Ternary Blended Green Concrete Incorporating Fly Ash, GGBS, and Agricultural Waste Ash

The construction industry accounts for approximately 8% of global anthropogenic CO₂ emissions, driven predominantly by Portland cement manufacture whose calcination process releases approximately 0.83 kg CO₂ per kg clinker produced. Supplementary cementitious materials (SCMs) derived from industrial and agricultural by-products — including coal combustion fly ash (FA), ground granulated blast furnace slag (GGBS), silica fume (SF), and rice husk ash (RHA) — offer a technically sound and environmentally compelling route to reducing cement clinker demand while simultaneously valorising waste streams that would otherwise require landfill disposal.This experimental study designs, prepares, and evaluates six ternary blended concrete mix proportions using a Taguchi L9 orthogonal array, investigating the combined effects of FA, GGBS, SF, and RHA substitution on 28, 56, and 90-day compressive strength, split tensile strength, flexural strength, water absorption, and chloride ion penetration resistance. Life cycle assessment (LCA) using SimaPro v9.3 quantifies embodied CO₂, cumulative energy demand, and freshwater eutrophication potential across all mixes relative to a plain OPC M40 reference. The optimal ternary mix (M5: 40% FA + 20% GGBS + 10% RHA by cement weight) achieves 90-day compressive strength of 58.4 MPa — exceeding the OPC reference (46.3 MPa) by 26.1% — while reducing embodied CO₂ by 31.4% (289 vs. 421 kg CO₂-eq/m³). Chloride penetration resistance improves by 47.3% and water absorption reduces by 40.5% in the optimal mix, demonstrating enhanced durability performance attributed to pozzolanic reaction product densification of the interfacial transition zone.