An overview of the utilisation of Fe-rich residues in alkali-activated binders: Mechanical properties and state of iron

Iron-rich alkali-activated materials (Fe-AAM) are considered potential alternatives to ordinary Portland cement (OPC) to limit CO2 emissions and convert several metallurgical wastes into useful products. Unlike conventional aluminosilicate alkali-activated systems in which the role of the precursor's main constituents and the reaction products are well defined to some extent, the limited knowledge of the role and state of iron in AAMs restricts its utilisation in the construction sector. Nevertheless, several studies have shown the ability of iron to participate in the formation of alkali-activation reaction products, which induces high compressive strength (over 100 MPa) and provides both environmental and material performance benefits. In this study, we critically evaluate existing data on Fe-rich raw materials, activators, co-binders, mechanical properties, curing types and the reactivity and role of iron in Fe-AAMs. [Display omitted] •Alkali activation is a promising way to utilise Fe-rich residues.•A critical evaluation of existing data on Fe-rich AAMs is provided.•Over 100 articles about alkali activation of Fe-rich materials are analysed.•Fe-rich AAMs have both environmental and performance benefits.