Stabilization of Soil Sub-grade Using GSB Material for Construction of Pavement

The construction of roads often necessitates soil stabilization in the sub-base and sub-grade regions when the soil exhibits poor strength due to softness, swelling, or low shear strength. While compaction can enhance many soils, it may not be sufficient for expansive soils, which necessitate the use of stabilizing agents, especially when dealing with weak or expansive soils. A crucial parameter in pavement design is the California Bearing Ratio (CBR), which measures soil strength. This study aimed to enhance CBR values by incorporating granular Sub-Base (GSB) material. Laboratory tests were conducted on various soil samples to determine their geotechnical properties, including Atterberg's limits, compaction characteristics, and CBR. The results indicated that increasing the percentage of GSB led to an increase in plasticity index and maximum dry density while decreasing optimum moisture content. Notably, CBR values significantly improved with higher GSB percentages. To achieve a CBR value exceeding 5, CL soils required 12-16% GSB, while CI soils needed 8-12%. This research provides valuable insights for optimizing GSB usage in pavement design, considering soil characteristics and traffic demands. Future research could explore the use of crushed demolition aggregates and fine marble powder, as well as evaluate permeability and consolidation characteristics for long-term performance and durability. . Key Words: Granular Sub-base (GSB), Atterberg’s Limit, Plasticity Index, Compaction, CBR, Expansive Soil.