Expansive soils, such as black cotton soil, are problematic due to their high swelling potential, leading to structural instability. This study investigates the effect of lime-sand piles on reducing swelling pressure and enhancing the mechanical properties of expansive soils. A series of laboratory tests, including unconfined compressive strength (UCS), California bearing ratio (CBR), and swelling pressure tests, were conducted on untreated soil and soil reinforced with lime-sand piles of varying diameters (12, 16.5, and 23 mm) and configurations (single, three, and five piles). The 16.5 mm diameter single pile configuration provided the best reduction in swelling pressure, achieving a 53.4% decrease compared to untreated soil. The single 12 mm pile configuration showed the second-best performance, with a 44% reduction in swelling pressure. Contrary to expectations, multiple pile configurations (three and five 12 mm piles) were less effective, with swelling pressures higher than the single 12 mm pile but still lower than untreated soil. The 16.5 mm single pile configuration also increased the CBR value by 71.89% compared to untreated soil. These findings demonstrate that lime-sand piles are an effective solution for improving the stability of expansive soils, with pile diameter and configuration being key parameters for optimization. The results suggest a complex relationship between pile number, diameter, and effectiveness in reducing swelling pressure, highlighting the need for careful design in soil stabilization projects.