Transforming Agricultural Residues into High-Performance SCMs through Mechanochemical Activation

Despite the abundance of ashed agricultural residues and their potential as supplementary cementitious materials (SCMs), given a high silica content (up to 90 wt.%), their high water demand limits their use. This challenge compromises both the fresh-state workability and mechanical performance of supplemented concrete – a pivotal challenge for countries in the Global South with large agricultural sectors and low production of other industrial SCMs. To address this limitation, we investigate two innovative mechanochemical methods and their effects on the fresh-state workability issues of these ash-based SCMs. This presentation will share our latest results describing how the mechanochemical activation of rice hull ash influences the silica atomic coordination and improves both the workability and compressive strength of supplemented cementitious materials. Improvements in workability lead to a near 6-fold increase in compressive strength at 28 days, reaching ~8,000 psi at replacement levels of 20 wt.%. By enabling the manufacturing of high-performance SCMs from agricultural residues, our findings offer a viable pathway to utilize abundant agricultural ashes in global concrete production, addressing environmental and SCM supply challenges in the Global South.