Decarbonization of the concrete industry has arisen as one of the main priorities for the construction sector in order to mitigate the negative climate impact associated with construction. The carbon emissions of concrete mainly originate from the production of cement, and it is essential to find supplementary cementitious materials (SCMs) to achieve eco-friendly construction materials. The use of tailings as SCMs could reduce the carbon footprint of concrete, as well as improve the environmental impact of waste management within the mining sector. To investigate the effects of using lead–zinc tailings as a partial replacement for ordinary Portland cement (OPC), an experimental study was conducted. Two types of lead–zinc tailings were utilized in the experiments to replace 10% and 20% of OPC. A mechanical activation method was adopted using a vibratory cup mill. The effects of activation on the tailings’ particle size distributions and mineralogy were evaluated. The results indicated that the activation was insufficient to promote the pozzolanic activity in T1 and only partially promoted it in T2. A total of 18 different tailing-based mortar (TBM) specimens were produced from the raw and activated tailings, and their flowability, setting time, and compressive strengths after 7, 28, and 90 days were evaluated. The microstructures of the specimens were analyzed using scanning electron microscopy with energy dispersive X-ray spectroscopy. No alteration of mineralogy was observed in T1 after activation; however, a reduction in muscovite was observed in T2. The TBM specimens with 10% activated tailings exhibited comparable 28-day compressive strengths to the control specimen. For the replacement level above 10%, there was a loss of compressive strength at 28 days, both for the activated and raw tailings and for both T1 and T2. Evaluation of the microstructure showed that the use of tailings caused regions in the cement matrix with high metal concentrations. Microcracks could be observed in or around such grains in several cases. The study demonstrated that 10% of OPC can be replaced by lead–zinc tailings while retaining the compressive strength of the specimens.
Johansson et al. (Wed,) studied this question.