Sustainable Utilization of Waste Foundry Sand and Sodium Chloride in Soil Stabilization

The expansion and contraction properties of black cotton soil make it a challenging task to construct structures on it. Hence, modifying its expansion and contraction behavior is imperative to make black cotton soil appropriate for construction purposes. This study aims to assess the geo-technical properties of black cotton soil through laboratory testing, incorporating waste foundry sand (WFS) and sodium chloride (NaCl) to utilize the combination as sub-grade material. Differential free swell, consistency limits, the standard Proctor test, and California bearing ratio (CBR) tests are conducted with varying amounts of both materials. The laboratory testing reveals that the addition of the appropriate amount of waste foundry sand, sodium chloride, or both, improve the geo-technical properties of black cotton soil (BCS). Furthermore, using the CBR values obtained, the thickness of flexible pavement is designed with the IITPAVE software and evaluated against the IRC: 37-2018 recommendations. The software analysis demonstrates a reduction in pavement thickness for varying levels of commercial vehicles per day such as 1000, 2000, and 5000 CVPD across all combinations. This mixture not only addresses the issues related to black cotton soil but also provides an economical solution for soil stabilization and proves to be sustainable as it involves the utilization of waste materials such as waste foundry sand.