Transforming iron ore tailings into high reactivity binders for multifunctional and eco- efficient foamed concrete

Iron Ore Tailings (IoTs) were mainly released from ore concentrating processes, which caused serious environmental problems and resulted in a large number of emissions detrimental to the ecological balance. The wise application of IoTs served the purpose of environmental protection and sustainable development. Therefore, the objective of this study was to perform a comprehensive and extensive examination of IoTs’ application as ternary supplementary cementitious materials (SCMs), by combining FA with RHA for sustainable foamed concrete (FC) production. Five batches of FC mix were prepared with varying amounts of ternary SCMs, including the control mix. IoTs, RHA, and FA were used as partial replacements for cement, with weight fractions of 0%, 12%, 24%, 36%, 48%, and 60%. The ternary SCMs system consisted of IoTs, FA, and RHA, with a weight ratio of 1:1:1. The freshness, pore structure, transport, and strength properties were evaluated. The test results showed that FC’s setting time and hardened density increased, while the mix workability decreased with increasing ternary SCMs substitutes. Substituting 24% SCMs improved porosity, water absorption, sorptivity, intrinsic permeability, chloride ion diffusion, and resulted in a denser microstructure. This significantly improved the compactness of the FC mixture, resulting in the best strength properties. The test findings indicated a significant improvement of 14.62%, 24.20%, and 28.84% in compressive, flexural, and splitting tensile strength, respectively, compared to the control mix by substituting 24% SCMs. The research findings enhanced the sustainable utilization of IoTs as an eco-friendly ingredient for substituting cement in FC production.