Corrosion resistance of reinforcement steel embedded in chloride contaminated concrete with and without metakaolin

One of the most remarkable drawbacks of the reinforced concrete structural elements is the corrosion of reinforcement. Especially, in marine structures or in such environments where chloride contamination risk exist this issue gains much importance. In this study, chloride contamination of the concrete was implemented by adding 0%, 1.5%, 3%, and 5% NaCl by weight of the total binder content, into concrete. To assess the influence of metakaolin (MK) incorporation on the corrosion resistance of the chloride contaminated concrete, 5% and 15% MK replacement levels by the total weight of the binder were assigned in concrete production. The corrosion behaviors of reinforcing bars embedded in concretes were monitored through accelerated corrosion test, corrosion current density and the corresponding corrosion rate by linear polarization technique (LPR). Moreover, the electrical resistivity of concrete was measured. Analysis of the test results indicated that MK was proved to be very effective in inhibiting the active corrosion of concrete even at severe chloride contamination levels.