Experimental Study on the Stabilization of Expansive Soil with Blended Fine Cinder Gravel and Waste Marble Dust: A Case Study of Jimma Town

This study investigates the potential of Waste Marble Dust (WMD) and fine Cinder Gravel (CG) to enhance the engineering properties of expansive soils, which are prone to volume changes due to moisture fluctuations. The research aimed to stabilize expansive soils, classified as A-7-6(37) in the AASHTO system and CH in the USCS system, for use as sub-grade materials in road construction. Mechanical stabilization technique was used in this study. Soil material is dried in air and mixed with 8%, 12%, 16%, and 24% of CG and MD. The key findings include; Plasticity Index reduced from 34.09% to 10.28%, Free Swell Index decreased from 81.8% to 36.4%, Optimum Moisture Content decreased from 24.02% to 14.00%, Maximum Dry Density increased from 14.22 kN/m³ to 16.19 kN/m³, California Bearing Ratio (CBR) increased from 1.00% to 22.69% and Unconfined Compressive Strength (UCS) increased from 112.9 kPa to 311.7 kPa. Optimal stabilization was achieved at a 16% replacement of both WMD and CG, improving the soil's strength significantly. This study concludes that WMD and CG are effective stabilizers for expansive soils, meeting the requirements for sub-grade material in road construction and offering improved durability and performance. Keywords: Expansive soil, Stabilization, Swelling, Shrinkage, Waste marble dust, Cinder gravel, Sub-grade soil, CBR value.