Abstract:Copper tailings pose a critical challenge to sustainable mining development due to their massive production volume, difficulties in large-scale disposal, and high safety risks associated with tailings pond storage. This study developed subgrade materials using copper tailings as the primary raw material, supplemented with plastic clay and cement. Comprehensive experimental characterization was conducted, including compaction tests, unconfined compressive strength (UCS) tests, California Bearing Ratio (CBR) tests, freeze-thaw cycle tests, wet-dry cycle tests, leaching toxicity analysis, and microstructural characterization. Key findings demonstrated that the compressive strength increased significantly with higher cement content. At 5% cement content (by mass), the 7-day UCS reached 5.23 MPa. After 5 freeze-thaw cycles, the compressive strength ratio (BDR) exceeded 80%. Following 25 wet-dry cycles, the retained strength remained above 3 MPa. Heavy metal ion concentrations in leachates complied fully with GB/T 5749—2022 Standards for Drinking Water Quality limits. This research comprehensively validated the favorable mechanical properties, durability, and environmental compatibility of copper tailings-based subgrade materials. The results confirmed the technical feasibility of utilizing copper tailings as the principal raw material for subgrade construction, providing a novel pathway for large-scale disposal and resource utilization of copper tailings. This approach held significant promise for advancing tailings-free mining initiatives and promoting sustainable green mining practices.