Enhancing Strength, Durability, and Dynamic Behavior of Roads in Northeast India: Soil Stabilization Using Lime, Rice Husk Ash, and Coir Fiber Reinforcement

Enhancing the strength and durability of clayey soil subgrades is essential for improving the long-term performance of pavements, particularly in regions prone to adverse climatic and seismic conditions. The northeastern region of India, which experiences high rainfall and frequent seismic activity, often faces rapid road deterioration due to these natural factors. This study investigates the stabilization of clayey soil using lime (5%) and rice husk ash (RHA) (10%), reinforced with coir fiber (1.5%), to improve its bearing capacity, dynamic response, and durability. The research explores the sustainable utilization of agricultural and industrial byproducts to enhance soil performance while promoting environmentally friendly construction practices. Resonant column tests were conducted at varying confining pressures (50, 100, and 150 kPa) to evaluate shear modulus and damping characteristics of stabilized soil. The findings indicate that lime-RHA stabilization and coir fiber reinforcement significantly increased the shear modulus, with the highest improvement observed at 150 kPa. Additionally, the damping ratio increased with strain; however, specimens that had stabilized exhibited lower damping due to higher soil density and reduced energy dissipation. Durability assessments through wetting and drying tests revealed that fiber reinforcement mitigated mass loss, preserved unconfined compressive strength, and minimized crack formation, making the soil more resilient to environmental cycles. Furthermore, California bearing ratio tests demonstrated that stabilization enhanced the load-bearing capacity of the soil, reducing the required pavement thickness and overall construction costs. The results suggest that the integration of lime, RHA, and coir fiber presents a sustainable and cost-effective solution for subgrade stabilization, reducing reliance on conventional materials while utilizing industrial and agricultural waste. This study underscores the potential of green stabilization techniques in enhancing the durability and structural integrity of transportation infrastructure, particularly in regions with challenging environmental conditions.