Reimagining Copper Tailings in Sustainable Concrete Mixtures: Multi-Scale Mechanisms, Environmental Trade-Offs, and Future Innovations

Copper tailings (CT), a major co-product in copper extraction and processing operations, pose severe environmental concerns because of their vast quantities, occupying large areas of land, causing dust pollution, and possibly leading to heavy metal contamination. At the same time, the concrete industry faces increasing requirements to minimize carbon emissions and consumption of primary resources. The current paper critically reviews the literature on the use of CT in both cement-based and alkali-activated concrete compositions in terms of material characterization, engineering properties, durability, microstructure formation, and sustainability considerations. Evidence indicates that CT can be used as a supplementary cementitious material, fine aggregate replacement, or micro-filler for improving particle packing and compacting the matrix to boost its mechanical properties in an optimized ratio range. Furthermore, CT composites are more resistant to chloride penetration, sulfate corrosion, and other deterioration mechanisms. CT is known to refine the microstructure by creating dense hydration products while immobilizing any hazardous heavy metals. Finally, life cycle assessment studies point out the environmental benefits of using CT as a waste product in concrete composites. In addition to a summary of existing knowledge, this paper sheds light on critical gaps associated with long-term performance, standardization, and field validation. The paper also outlines important new directions in the areas of artificial intelligence, machine learning, and digital twins for performance modeling and sustainability. The implications of this study show the great promise of CT as a highly efficient raw material for future carbon-negative building materials.