Evaluating the effectiveness of rice husk ash and lime in subgrade soil enhancement

This study explored the use of Rice Husk Ash (RHA) and lime as soil stabilizers for subgrade soil. RHA, a by-product of rice milling, poses environmental hazards if improperly disposed of. The optimal RHA content for subgrade stabilization is 15%, combined with 3% lime. The research found that RHA not only improves subgrade properties but also mitigates environmental pollution and offers a cost-effective stabilization method. The study evaluated engineering properties like plasticity index, maximum dry density (MDD), optimum moisture content (OMC), and California Bearing Ratio (CBR). Results showed a significant decrease in plasticity index and an increase in MDD with RHA addition up to 15%. However, further increase in RHA content led to a decrease in MDD. The combination of 15% RHA and 3% lime exhibited the highest CBR improvement (61.48%), indicating enhanced soil strength. This research suggests that RHA may be a sustainable and cost-effective subgrade stabilization material that improves pavement performance and waste utilization. RHA is abundant, easy to obtain, and economical as compared to cement as a soil stabilizer, reducing disposal issues and environmental impact.