Utilization of iron ore tailings with high volume in green concrete

In this study, the potential of converting iron ore tailings (IOTs) into sustainable building materials was explored. IOTs were combined with fly ash (FA) and ground granulated blast-furnace slag (GGBFS) to prepare IOTs-based supplementary cementitious materials (SCMs). A concrete mix using 100% IOTs-aggregate was also prepared. The aim was to address the challenge of producing high-performance concrete using IOTs by replacing cement, coarse aggregate, and fine aggregate simultaneously. The compressive strength, transport properties, pore structure, and interfacial transition zone (ITZ) properties of the concrete were tested. The results showed that the 28-day compressive strength of concrete can reach 49 MPa when IOTs-based SCMs replaced 30% of the cement. The IOT-based SCMs also improved the impermeability and compressive strength of the concrete, reduced the porosity of the concrete matrix and ITZ, refined the pore size of the concrete matrix, and reduced the unhydrated rate of particles in the ITZ. However, there was competition between the matrix pore structure and ITZ, and balancing their performance is essential to achieve multi-objective optimization of concrete performance. This work demonstrates the potential for high-volume utilization of IOTs in sustainable construction materials and enhances our understanding of IOTs-based concrete properties.