Effect of Chloride and Carbonate Salts on Geotechnical Properties of Expansive Soil

This study investigates the influence of chloride and carbonate salts on the engineering properties of highly expansive soils, with a focus on improving their geotechnical performance for construction applications. Expansive soils, known for their high plasticity and swelling potential, pose significant challenges to infrastructure stability. In this research, three types of salts: sodium chloride (NaCl), potassium chloride (KCl), and calcium carbonate (CaCO₃), were added to clayey soil at varying concentrations to evaluate their impact on Plasticity Index (PI), Unconfined Compressive Strength (UCS), and Free Swell (FS). The results showed that all three salts improved soil stability, with KCl exhibiting the most pronounced effect. The PI and Fs decreased significantly, while UCS increased, peaking at an optimal salt concentration of 7.5%. Notably, the UCS increased from 138 kPa to 289 kPa with KCl, indicating a substantial improvement in strength. These enhancements are attributed to salt-induced flocculation, which aggregates clay particles into larger, more stable clusters and reduces soil plasticity.