Corrosion behavior of steel rebar in coal gangue-based mortars

Abstract

Corrosion of steel rebar is the most important durability problem of reinforced concrete. The aim of this research was to investigate the corrosion behavior of steel rebar in simulated pore solutions and gangue-blended cement mortar. The simulated pore solutions were based on the pore solution composition of gangue-blended cement. The pH and Cl− concentration of simulated pore solutions had significant effects on corrosion potential. However, an increase in pH reduced the influence of Cl− concentration on corrosion potential. The corrosion behavior of steel rebar in gangue-blended cement is different from that in simulated solutions. The gangue cementitious mortar surrounding steel rebar provides stable passivity environments for steel, leading to a decrease in ion diffusion coefficients. Alternating current impedance (ACI) analysis results indicated that the indicator Rc for concrete resistivity is higher for gangue mortar than for ordinary Portland cement (OPC), which improves its corrosion potential. The results from energy dispersive X-ray analysis (EDX) showed more aluminates and silicates at the rebar interface for gangue-blended cement. These aluminates improve the chloride binding capacity of hydrates in mortar, and increase the corrosion protection of steel rebar.