Corrosion behavior of steel in a mortar containing ferronickel slag

Abstract

Ferronickel slag (FNS) has been currently developed for supplementary cementitious material in concrete mixtures. The present study concerns the corrosion resistance of FNS-mixed mortar against a chloride and carbonation environment. The replacement ratio of FNS was 10, 30, and 50% to total binder with ordinary portland cement (OPC). The corrosion resistance was evaluated by monitoring of corrosion potential and current density, followed by mass loss of steel reinforcing bar after the monitoring. As a result, it was found that FNS-mixed mortar had a higher corrosion potential and lower corrosion current density at 10 and 30% FNS replacement, presumably due to increased chloride binding capacity and denser pore structure. At a carbonation-accelerated condition, FNS-mixed mortar always had lower pH values at every depth, compared to OPC ones, imposing a higher risk of carbonation. The acid neutralization capacity of FNS has mostly equated buffering capacities at different pH ranges.