Developing Concrete Using +80 wt% of Copper Tailings and Slag in Chile: Insights into Sustainable Waste Material Utilization

This study addresses the ongoing challenge of mitigating the environmental risks posed by metal tailings storage facilities while simultaneously offering a novel and sustainable alternative to conventional construction materials. This study examined the utility of copper tailings and slag, two main byproducts of the mining industry, through the formulation of concrete that incorporates over 80% of these materials by weight. Comprehensive physical, chemical, and mineralogical analyses were performed following the Chilean and international standards. These assessments confirmed the presence of potentially hazardous elements and demonstrated the effectiveness of passivation treatments that make these materials suitable for reuse. Three experimental concrete mixtures were designed and tested under optimum laboratory conditions. The results showed that the compressive strengths exceeded 25 MPa within 7 days, whereas conventional concrete typically requires 28 days to achieve a comparable performance. The mixes also demonstrated effective immobilization of acidic and metallic components, ensuring compliance with the Chilean national regulations governing aggregates and construction materials. An economic evaluation highlighted the strong competitiveness of this approach. Production costs decreased by approximately 74% compared to traditional Portland cement concrete, primarily because of the lower raw material costs of tailings and slag. This research presents a technically feasible, economically viable, and environmentally beneficial solution that supports circular economy models in Chile, thereby providing a replicable framework for international applications.