Stablizetion of Expansive Soil using Industrial Solid Waste

Expansive soils pose significant challenges to civil engineering projects due to their high swelling and shrinkage potential, which often leads to structural damage such as cracks, heaving, and settlement. This study investigates the effects of two waste-based stabilizing agents—Fly Ash and Demolished Construction Waste Powder (DCWP)—on the geotechnical properties of expansive soil. Soil samples were treated with 7.5%, 12.5%, and 15% of each additive by dry weight and evaluated for changes in Liquid Limit (LL), Plastic Limit (PL), Plasticity Index (PI), Free Swell Index (FSI), Maximum Dry Density (MDD), and Optimum Moisture Content (OMC). The results show that Fly Ash significantly reduces plasticity and swell potential due to its pozzolanic characteristics, with the most notable improvements observed at 15% dosage. On the other hand, DCWP enhances compaction properties and dry density through improved gradation and mechanical interlocking but is less effective in reducing plasticity. Both materials contributed to a decrease in OMC and FSI, promoting improved soil behavior. The study concludes that Fly Ash is more suitable for controlling expansive behavior, while DCWP can be beneficial for enhancing soil density, thereby promoting sustainable construction and effective solid waste management.