Copper tailings as a potential additive in concrete: consistency, strength and toxic metal immobilization properties

This paper presents the results of a study investigating the consistency, hardened and toxic metal immobilization properties of concretes containing copper tailings as an additive. To compare the effects of copper tailings on strength and strength related properties across two concrete classes, two series of concretes with 0.57 and 0.50 water-to-binder ratios are used. For each series, three mixtures incorporating copper tailings at 0%, 5%, and 10% addition levels by mass are prepared. Copper tailings have a slight negative impact on the slump, setting time and porosity of mixtures. However, improved mechanical strengths and abrasion resistance, and reduced chloride penetration compared to the control specimens are observed in mixtures incorporating copper tailings. Toxicity characteristic leaching test results revealed that the release of heavy metals from mixtures containing copper tailings is considerably lower than the United States Code of Regulations limits. Overall, it seems that there is a potential for the use of copper tailings as a zero-cost, environmentally-friendly additive in concrete, especially at a 5% addition level.