Mine Tailings as Supplementary Cementitious Materials: Properties, Performance, Mechanochemical Activation, and...

The environmental impacts associated with Portland-cement production have driven decades of research into sustainable supplementary cementitious materials (SCMs). An emerging alternative, mine tailings, has been gaining attention lately due to its large availability, environmental burden, and potential for resource recovery. The paper reviews the use of mine tailings in concrete and their potential as an alternative SCM source. Fundamental properties, such as chemical composition, mineralogy, crystalline structure, fineness, and amorphous content, are reviewed for their influence on the behavior of mine tailings in cement-based systems. With low reactivity and variable compositions posing the main restrictions, mechanochemical activation (MCA) is assessed as an effective strategy to enhance their performance. By reducing the particle size, increasing the specific surface area, and inducing structural disorder, mechanochemical treatment can improve the pozzolanic or filler activity of mine tailings and thereby increase their suitability for blended cement applications. Overall, this structured narrative review highlights mechanochemically activated mine tailings as a potential pathway toward low-carbon concrete and circular material management, all while highlighting the need for further research that will provide additional insights regarding the correlations between mine tailings' properties, milling conditions, and reactivity, as well as the long-term durability of concrete incorporating them.