The Influence of Activation Methods on the Electrical Resistivity of Iron Ore tailings-Based Geopolymers

Abstract

large-scale stockpiling of iron ore tailings (IOTs) presents significant environmental challenges. This study explores the use of IOTs as a precursor for geopolymer production, offering a sustainable alternative to traditional Portland cement. The research focuses on enhancing the low reactivity of IOTs through various activation methods—thermal, chemical, and a combined thermo-chemical approach—and evaluates the resulting geopolymer’s durability, with a particular emphasis on its electrical resistivity. The results demonstrate that appropriately activated IOT-based geopolymers exhibit superior durability properties. A 3-day resistivity comparable to that of conventional concrete was achieved, with values exceeding 200 kΩ·cm after 28 days of curing. An optimal thermal activation temperature of 700°C was identified for the specific tailings used. Notably, the synergistic effect of thermo-chemical activation (e.g., 500°C with NaOH) produced a geopolymer with higher resistivity than one activated thermally at 700°C alone. The high resistivity is attributed to the formation of a dense, three-dimensional N-A-S-H gel network and a pore solution chemistry dominated by less mobile Na+/K+ ions, in contrast to the highly mobile OH- ions in traditional concrete. This dense microstructure and high resistivity effectively impede the transport of harmful agents, thereby significantly mitigating steel corrosion, chloride ingress, and carbonation. In conclusion, this study validates the feasibility of producing high-performance, low-carbon building materials from IOTs, providing an effective pathway for solid waste utilization and contributing to the reduction of the construction industry’s carbon footprint.