Performance Of Rice Husk Ash And Cement As Soil Subgrade Stabilizing Agents

Abstract

Soil stabilization is a critical technique for enhancing the engineering performance of weak and expansive soils, particularly for road and pavement construction. Expansive clays, characterized by high swell potential, low shear strength, and poor bearing capacity, pose significant challenges for infrastructure development, as observed along the historic Mughal Road connecting Kashmir valley to Poonch–Rajouri. In this study, locally available soils with inherently low strength were stabilized using rice husk ash (RHA), an agricultural by-product, and cement in varying proportions. Laboratory investigations, including compaction characteristics, optimum moisture content (OMC), maximum dry density (MDD), and California Bearing Ratio (CBR) tests, were performed to assess improvements in soil properties. Results revealed that the addition of RHA and cement significantly increased soil strength and stability, with CBR values improving from 1.88 to 7.03 as RHA content increased from 0% to 7%. The optimum stabilizer combination was identified as 10% RHA by dry weight of soil, providing notable strength gains while promoting sustainable use of agricultural waste. Literature studies corroborate these findings, highlighting the synergistic effects of RHA with lime, gypsum, and other admixtures. Overall, the study demonstrates that RHA-based stabilization offers a cost-effective, eco-friendly solution for upgrading weak soils and ensuring durable road infrastructure.