A comparative study on the practical use of low sulfide base-metal tailings as aggregates for rendering and masonry mortars

The reuse of some industrial by-products in the construction industry saves natural resources and energy, while at the same time reduces environmental problems related to their surface disposal. Mine tailings are currently among the largest industrial by-products in the world, and yet, only limited studies have been conducted to evaluate their reuse potential. Moreover, abandoned base-metal tailings are increasingly used in some developing countries for the manufacture of mortars without any control, engineering basis or environmental concern. In this study, an experimental program using mechanical tests, mineralogical investigations and leaching tests is presented to assess the use of low sulfide base-metal tailings, with varying properties, as fine aggregates for rendering and masonry mortars. An authentic case study illustrating their use in Moroccan construction is additionally presented. Overall, it was observed that the main properties affecting the performances of these tailings-based mortars are the residual Pb-Zn concentrations and the fine content of each tailing. The Pb-Zn fraction, when using the appropriate substitution level, may serve as an active set retardant improving mortars setting time. The leaching of metals was also successfully stabilized in mortars.