A STUDY ON THE IMPACT OF RICE HUSK ASH ON STABILIZING EXPANSIVE SOILS

Abstract

Soil stabilization using agro-industrial by-products has gained significant attention due to its environmental and economic benefits. This study evaluates the potential of Rice Husk Ash (RHA), a pozzolanic material rich in silica (up to 90%), for stabilizing clayey soil. Laboratory experiments were conducted by blending soil with RHA at varying dosages of 5%, 10%, 15%, and 20% by dry weight. The Atterberg Limits showed a decrease in plasticity index from 24.8% (untreated) to 15.3% at 15% RHA content, indicating improved workability. Standard Proctor Compaction tests revealed a reduction in Maximum Dry Density (MDD) from 1.72 g/cm³ to 1.59 g/cm³ and an increase in Optimum Moisture Content (OMC) from 18.2% to 22.7%, reflecting the lightweight and absorbent nature of RHA. Unconfined Compressive Strength (UCS) increased from 98 kPa for untreated soil to 236 kPa at 10% RHA after 28 days of curing, marking a 141% improvement. Similarly, the Unsoaked California Bearing Ratio (CBR) value increased from 3.4% (untreated) to 9.8% at 15% RHA, a 188% enhancement. These findings suggest that RHA significantly improves the mechanical properties of clayey soil and can be effectively utilized for sustainable ground improvement in geotechnical engineering applications.