Mechanical Performance of Copper-Tailings Concrete with Steel Fibers for Potential Underground Support Applications

The increasing accumulation of mine tailings has motivated the development of sustainable strategies for their reuse within the framework of the circular economy. This study evaluates the mechanical performance of four laboratory-cast concrete mixtures: a reference mixture, a mixture in which copper tailings were incorporated at 8% of the base mixture mass to replace an equivalent mass of natural coarse sand, and two tailings-based mixtures reinforced with 0.4% and 1.2% steel fibers. Their compressive strength and elastic modulus were evaluated after 7, 14, 28, and 100 days of curing to assess the mechanical performance of the proposed mixtures and their potential relevance for underground mining support applications. The results showed that after 100 days, the 8% copper tailings mixture reached a compressive strength of 41.6 MPa, compared with 39.6 MPa for the conventional mixture. The addition of steel fibers produced a slight reduction in compressive strength and stiffness at early curing ages; however, comparable mechanical performance was achieved after extended curing. The observed improvements are primarily consistent with the filler effect and improved particle packing associated with the fine tailings fraction, although the underlying microstructural mechanisms were not directly evaluated in this study. Overall, the results provide preliminary evidence that copper tailings can be incorporated into laboratory-cast concrete mixtures with steel fibers, supporting their further evaluation for potential underground support applications.