Enhancing Geotechnical Properties of Silty Soil: Exploring the Potential of Rice Husk Ash and Lime for Subgrade Stabilization

The reuse of industrial and agricultural waste materials in geotechnical engineering offers both environmental and technical advantages. In this study, the potential of rice husk ash (RHA) and lime, used individually and in combination, was investigated for the stabilization of silty soil intended for subgrade applications. RHA was added at ratios of 5%, 10%, 15%, and 20% by dry soil weight, while lime was incorporated at 2.5% and 5%. Compaction characteristics, unconfined compressive strength (UCS), and California Bearing Ratio (CBR) tests were conducted to evaluate the effects of stabilization under different curing periods. The results indicate that the addition of RHA and lime led to an increase in optimum water content and a corresponding decrease in maximum dry unit weight. Compared to the natural soil, UCS values increased by approximately 2-6 times, whereas CBR values exhibited improvements of up to 5-8 times, particularly for specimens treated with combined lime-RHA mixtures. The findings demonstrate that RHA significantly enhances the effectiveness of lime stabilization and particularly by demonstrating the synergistic effect of combined lime-RHA stabilization under different curing conditions.