Abstract

The copper mining industry generates approximately 200 tons of tailings for every ton of ore extracted. On the other hand, the construction industry has a significant carbon footprint associated with cement manufacturing. Use of copper tailings as precursor for alkali activated materials (AAMs) can reduce the environmental impacts of construction and mining industry. Nevertheless, low reactivity of tailings is a challenge to increase their use. Two copper tailings were used, and an experimental design was conducted to determine statistical relevance of factors such as co-activator use, molar concentration, water-to-binder ratio among others. Reactivity was evaluated using isothermal calorimetry and thermogravimetric analysis, and compressive strength at 28 days was measured. The chemical structure and particle size distribution are similar for both samples, resulting in low reactivity of the tailings, as observed in isothermal calorimetry and thermogravimetric tests. This low reactivity is attributed to their high crystallinity, which is also reflected in the mixes designed with them. However, with the appropriate combination of factors, such as the water-to-binder ratio and the concentration of the activator, it is possible to achieve samples with a compressive strength close to 20 MPa at 60 degrees C, with both tailings showing the best performance. Despite the similarities, one of the samples exhibited better compressive strength performance compared to the majority of the samples. This enhancement is associated with the presence of amorphous mineral species and clays.