Utilization of the oil-contaminated soil as a sustainable resource in rural road construction and rehabilitation in oil-producing countries

Achieving sustainable, cleaner production (CP) is essential for reducing industrial waste and conserving natural resources, especially in rapid industrialization. One of the significant environmental challenges is the remediation and effective utilization of contaminated soils. While substantial research has been conducted on coarsegrained contaminated soils, a critical knowledge gap exists regarding the impact of oil contamination on the stabilization and long-term performance of fine-grained soils. This knowledge gap is especially evident when assessing soil performance over extended periods (e.g., 365 days). This study addresses this gap by investigating both the macro- and microstructural behavior of oil-contaminated fine-grained soils under different stabilization conditions and extended curing durations. Our research introduces an innovative approach to utilizing oilcontaminated fine-grained soils resulting from pipeline leaks as sustainable materials for soil stabilization. This method mitigates environmental hazards and promotes resource conservation by converting waste into cleaner construction materials. A comprehensive series of laboratory tests-including compaction, unconfined compressive strength (UCS), durability, California bearing ratio (CBR), mineralogical analysis, and microstructural examinations-was performed to evaluate soils with varying oil concentrations (4%, 7%, and 10%) and different cement contents (0%, 3%, 6%, and 9%). Results showed that the sample containing 4% oil and 9% cement exhibited the highest durability after six wet-dry (W-D) cycles, with durability 7.3 times greater than that of non-stabilized samples. Higher cement contents also significantly improved crack resistance, corresponding with durability findings. Long-term curing (365 days) increased UCS by 6.4%-8.5% in soils with 9% cement, highlighting the importance of extended curing for stabilizing oil-contaminated fine-grained soils. The microstructural analysis confirmed the formation of Calcium-Silicate-Hydrate (C-S-H), which is crucial for enhancing soil strength. These findings demonstrate the viability of this waste utilization strategy for future pavement stabilization, offering a cleaner production method that supports environmental sustainability and efficient resource management. The study provides a cost-effective solution for infrastructure projects by repurposing oilcontaminated soils as valuable construction materials by recycling industrial byproducts.