Stabilization of black cotton soil using lime and plastic waste

Black Cotton Soil (BCS) is a highly expansive clayey soil that poses significant challenges in construction due to its shrink-swell behavior, low bearing capacity, and poor shear strength. This study focuses on stabilizing Black Cotton Soil using lime and plastic waste to enhance its engineering properties for road and foundation applications. A series of laboratory tests, including Atterberg’s limits, compaction tests (OMC & MDD), direct shear test, and California Bearing Ratio (CBR) test, were conducted on untreated and stabilized soil samples. Various mix proportions of lime (4%, 5%, 6%, 8%) and plastic waste (0.5%, 1%, 1.5%, 2%) were evaluated to determine the optimal stabilization ratio. The results indicate that lime significantly reduces soil plasticity and increases strength, while plastic waste enhances durability by improving soil interlocking. The CBR value increased by more than 3 times, demonstrating improved load-bearing capacity suitable for highway subgrades and embankments. Additionally, stabilization reduced the soil's shrinkage and swelling potential, making it a viable alternative for sustainable construction. This study contributes to environmentally friendly engineering practices by reusing plastic waste while providing a cost-effective solution for problematic expansive soils. The findings support the integration of lime-plastic waste stabilization into road construction, foundation improvement, and infrastructure development in regions with Black Cotton Soil.