Comparative mechanical properties of conventional concrete mixture and concrete incorporating mining tailings sands

Abstract

This work examines the mechanical properties of mining tailing sands in conventional concrete mixtures for structural applications. Mining is one of the most important factors for city development and, in some cases, represents the primary or only source of economic income. However, this activity causes irreparable damage to the environment. Mining tailings are generated at the end of the entire mining process and subsequently spread in deposits or tailings. Mining has increased without control over the past years, causing damage to ecosystems and polluting environmental elements. Ideally, reuse and recycling of tailings, like all other recycling efforts, create financial assets. These activities help decrease consumption of natural resources, limiting waste production and encouraging innovation. Therefore, this study explores the technical and economic feasibility of using mining waste material or tailings sands as substitute fine aggregate in the design of conventional concrete (i.e., concretes with compressive strength of 21 MPa at 28 days). A life cycle assessment analysis was performed for the environmental impact of the mining tailings application in a concrete design using SimaPro 9.2 software. The LCA showed a reduction of 3% in the carbon footprint in case of 100% replacement of river sand with mining tailings. Positive environmental impacts in the ecotoxicity and human toxicity categories were also found because of the incorporation of heavy metals in the concrete matrix. The properties of this concrete alternative are in contrast to a conventional concrete design, demonstrating that it provides similar mechanical features. Based on the assessments from this paper, overall, from the mining aggregate investigated, it highlights more promising results, indicating that mining tailing aggregates can be a more sustainable alternative to conventional aggregate, providing a good balance between workability and strengths. Thus, this alternative might serve as an environmental solution that reuses mining waste generated during the extraction of metals.