Black cotton soil poses challenges in construction due to its expansive nature, limited bearing capacity, and vulnerability to volumetric reform, causing uneven settling and cracking. This impacts infrastructure, especially in rural development where road construction is essential. The California Bearing Ratio (CBR) is a crucial factor in rural road design on expansive soil. Typically, additional macadam layers are recommended, but local material availability can increase construction costs. Soil stabilization becomes a cost-effective solution, modifying geotechnical properties for strength, stability, and durability. Expansive soils, like black cotton soil, are particularly suitable for stabilization. India faces challenges with industrial waste causing environmental hazards. Stabilizing soil with industrial waste is a sustainable approach. A strong road network is vital for economic growth, but weaknesses in subgrade, infiltration capacity, landslides, and environmental concerns can hinder effectiveness. Recycled asphalt, a popular eco-friendly material, was studied for its impact on black cotton soil. Treating the soil with varying percentages of Recycled asphalt pavement Pavement (RAP) was found to yield optimal strength, making it suitable for low-traffic road sub-bases.In a practical application, Madikeri soil prone to road collapse was stabilized using RAP, with tests including grading, CBR, specific gravity, Atterberg's limits, and modified Proctor compaction. The study recommends incorporating 25% RAP for improved penetration resistance, presenting a potential method for stabilizing subgrade soil, balancing environmental preservation with cost considerations.