Utilization of Copper Tailings in Structural Ceramsite: Processing Optimization, Mechanical Performance, and Sustainability Assessment

The accumulation of copper tailings (CTs) has become a serious environmental challenge, and their recycling into building materials offers a practical way to reduce waste and support sustainable construction. This study examines the preparation of ceramsite from copper tailings, fly ash, and bentonite. The work aims to produce aggregates with high strength suitable for concrete applications. A uniform experimental design was used to explore how raw material ratios, sintering temperature, and sintering time influence the properties of ceramsite, while data analysis and process optimization were supported by regression-based modeling and numerical optimization techniques. The optimized ceramsite exhibited high compressive strength and very low water absorption. It had a dense matrix, contributing to its strength and durability. Microstructural investigations using X-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy revealed the presence of quartz, feldspars, mullite, and corundum, with mullite and corundum playing a key role in improving strength. To evaluate practical performance, concrete specimens were prepared with varying volumetric replacement ratios of ceramsite and tested for their mechanical properties. Results demonstrated that replacing ordinary crushed stone with ceramsite significantly enhanced both compressive and flexural strength. The greatest improvements appeared at moderate replacement levels, and overall performance still surpassed conventional concrete even at higher ratios. In addition, carbon emission assessments confirmed that producing ceramsite from CTs generated substantially lower emissions compared with traditional aggregates, supporting its role as a green material. Overall, this work demonstrates a promising pathway for recycling industrial waste into high-quality construction materials, providing both environmental and engineering benefits.