An Investigation of the Mechanical and Durability Properties of Hollow Concrete Blocks Made with Copper Mine Tailings as a Partial Cement Replacement

Abstract

The increase in copper productivity in Zambia has resulted in the expansion of disposal areas occupied by mineral wastes and tailings. This not only consumes land but also, due to insufficient management, poses negative environmental impacts and health risks to people. Therefore, efficient and sustainable approaches for the proper management of these waste materials must be developed. In this study, the potential utilization of copper mine tailings was assessed. After analyzing the physical and chemical properties of copper mine tailings from Kitwe Tailings Dam (TD25), hollow concrete block specimens were prepared. Copper mine tailings were used as a partial replacement for cement in the mix design, with replacement ratios as follows: 0% for CBCMT O% (control specimen), 10% for CBCMT1O%, 20% for CBCMT2O%, 30% for CBCMT3O%, 40% for CBCMT4O%, and 50% for CBCMT5O%, all aimed at achieving a target strength of 5 MPa. Specimen compressive strength was evaluated, and it was found that CBCMT1O% and CBCMT2O% achieved the target compressive strength at 28 days of age. Water absorption rates and resistance to acid attack were also assessed. Findings revealed that all specimens outperformed the control specimen in terms of these properties. Furthermore, the environmental feasibility of the hollow concrete blocks specimens was examined, and the results showed limited leaching of heavy metals from the specimens, with concentrations within permissible thresholds. Additionally, a statistical analysis was conducted to study the influence cell shape has on the specimens’ compressive strength. Aimed at identifying the optimal specimen type for achieving compressive strength at an early age, results indicated that cell shape had a significant impact on the 28-day age of hollow concrete blocks. The study proposes a novel copper mine tailings (waste) management approach, by utilizing the potential it has to replace cement in the production of hollow concrete blocks, evident from the observed enhancement of the mechanical and durability properties.