Integrated framework for evaluating iron ore tailings as construction materials: an Australian case study

Increasing demand for construction-grade sand and continued generation of iron ore tailings (IOT) from mining create significant challenges for aggregate resource management. Utilisation of IOT in construction remains limited due to variability in mineralogy and particle characteristics, creating uncertainty in performance and restricting industry adoption. An early-stage assessment framework was developed to evaluate site-specific IOT by integrating mine-site characterisation, concrete performance, safety and regulatory compliance, and market feasibility. Characterisation showed that the fineness modulus plays a significant role in the replacement rate of natural sand, as IOT can replace up to 100% of natural sand when matching the required range. Mineralogical analysis confirmed that IOT usually have minimal pozzolanic reactivity, limiting suitability as a cement replacement. Environmental and regulatory assessments demonstrated chemical stability, with pH values comparable to natural sand and heavy metal concentrations remaining well below United States Environmental Protection Agency regulatory limits. The fine and coarse IOT fractions utilised in this study were unsuitable for full sand replacement, whereas 40:60 and 50:50 blends allowed 100% natural sand replacement while maintaining compressive strength within 5% of the control (30.5 MPa). Tensile strength increased by up to 21.7%, while interfacial transition zone widths were reduced from approximately 1.96 μm in the control mix to 0.82–1.05 μm in IOT mixtures, indicating improved particle–matrix bonding. Economic assessment indicated that localised use near the source is most viable, with potential reductions of up to 20.9 million tonnes of natural sand extraction annually and gross material cost savings of up to AUD 1.32 billion per year.