<p>Concrete production poses environmental concerns due to high energy demand, CO₂ emissions, and the unsustainable disposal of industrial and agricultural waste.This study outlined the impact of rice husk ash (RHA) - an agro-waste ash of varying fineness as a partial replacement in Ground Granulated Blast Furnace Slag (GGBFS)-based alkali-activated binders (AAB), aiming to enhance sustainability. The primary aim of this study was to establish the role of RHA fineness and dosage in optimizing and assessing their potential as a sustainable and cost-effective alternative through mechanical, economic, and environmental evaluations. Sodium hydroxide and sodium silicate were used as alkali activators. RHA was incorporated at varying replacement levels and fineness grades to assess their impact on the fresh and mechanical properties of AAB. Additionally, a comparative assessment of cost and carbon footprint was also carried out. The results revealed that increased fineness of agro-waste ash significantly improved reactivity, leading to higher compressive strength and better workability. Among all mixes, 20% replacement with RHA sieved at 90 microns achieved the highest compressive strength of 54.9&#xa0;N/mm² and a carbon footprint reduction of 19.7% compared to control mix. These findings indicate that particle refinement enhances pozzolanic activity and binder densification, explaining the superior strength and workability observed. In conclusion, the integration of finely ground agro-waste ash into GGBFS-based AAB enhanced strength, reduced environmental impact, and proved to be cost-effective. Future research should focus on long-term durability, scaling up for structural applications, and the combined use of multiple agro-waste ashes to further optimize sustainability.</p>