<p>Soil contamination by gas-oil poses a major environmental and geotechnical challenge, often leading to a deterioration of mechanical behavior, reduced shear strength, and a loss of bearing capacity. This study examines the potential of using lime and sand to improve the geotechnical properties of very high plasticity clay soil (ω_l = 86%)and mitigate the adverse effects of gas-oil contamination. Laboratory tests, including Proctor compaction, Unconfined Compressive Strength (UCS), and California Bearing Ratio (CBR), were performed on natural and both natural and gas-oil-contaminated clay soils, with and without sand-lime treatment. The results show that contamination decreases the maximum dry density (MDD), stiffness and strength of the clay soil, whereas lime–sand stabilization significantly improves its compaction and mechanical behavior. Treating contaminated soils exhibited substantial improvements in UCS and CBR values compared to untreated samples, demonstrating greater load-bearing capacity and lower deformation potential. The findings confirm that combining lime and sand constitutes an efficient and sustainable remediation approach for hydrocarbon-contaminated clays, promoting the sustainable reuse of degraded soils in geotechnical and pavement applications.</p>