Investigation of laterite and black cotton soil using agricultural and industrial waste for road embankment

The rapid growth of urban areas and industrial activities has substantially increased the solid waste production, resulting in serious environmental and disposal challenges. The reuse of agricultural and industrial by-product in geotechnical engineering applications offers a sustainable alternative for both waste management and soil improvement. The research examines the enhancement of engineering characteristics of laterite soil and black cotton soil using waste glass (WG), plastic waste (PW), rice husk (RH), bagasse husk ash (BHA), and fly ash (FA) as stabilizing agents. Soil samples were treated with 0–9% waste admixture along with 5–20% fly ash by dry weight. Laboratory tests were conducted according to the Indian Standard (IS) procedures, including index property, modified proctor test, direct shear test, constant head permeability test, and California Bearing Ratio (CBR) test. The increase in the engineering performance of the soils was observed after soil stabilization. The maximum dry density for laterite soil increased by 65% and that for black cotton soil by 68% at optimum stabilization levels. The permeability decrease by nearly 26–29% for both soils. The shear strength parameters, cohesion and internal friction angle, showed considerable enhancement, particularly at 7% waste admixture combined with 15% fly ash. Furthermore, CBR values increased from 8.50% to 14.81% for laterite soil and from 6.75% to 11.21% for black cotton soil, indicating improvement in load carrying capacity. These improvements contributed to an estimated pavement thickness reduction of approximately 11–12% resulting in potential construction cost savings. The findings confirm that controlled incorporation of agricultural and industrial waste material can significantly improve soil performance and support sustainable road construction. However, excessive addition of waste materials may adversely affect compaction and strength characteristics. Therefore, identification of optimum stabilization proportions is essential. Field-scale validation and long-term performance studies are recommended for practical implementation.