Use of Tailings as a Substitute for Sand in Concrete Blocks Production: Gravimetric Mining Wastes as a Case Study

This study assesses the feasibility of reusing tailings from a gold mining area in southern Ecuador in concrete block (CB) manufacturing. For this purpose, physical, chemical, and mineralogical analyses were performed to characterize the tailings. Furthermore, the tailing samples were subjected to the European Standard EN 12457-2 leaching test to assess the potential risk of releasing toxic elements (PTE) into the environment. The CBs were made conventionally and replaced 50% and 70% of the sand with tailings. Lastly, mechanical resistance tests (MRTs) were performed to evaluate the indirect tensile strength, compressive strength, and absorption. The study results show that tailings are feasible as a substitute for sand in manufacturing CBs. Furthermore, the leaching tests complied with the set limit for non-hazardous mining wastes. Regarding the MRT, the CBs made with 50% of tailings were the ones that gave the most favorable results; however, the compressive strength and absorption did not comply with the regulations. In this regard, making CBs with less than 50% tailings is recommended to evaluate their mechanical properties. This study offers an alternative for recycling tailings and contributing to the circular economy.