Inhibitor evaluation in different simulated concrete pore solution for the protection of steel rebars

Corrosion of reinforcement steel forms a huge problem worldwide. A possible remedy for this problem is the application of corrosion inhibitors. The purpose of this research is to evaluate different inhibitors for both types of corrosion that can occur in reinforced concrete: pitting corrosion (by chloride attack), and uniform corrosion (by a drop in pH). Potentiodynamic polarization measurements in realistic concrete pore solutions (CPS) revealed three critical situations — representing pitting and uniform corrosion, and the combination — in which the inhibitor needs to act. According to polarization experiments and micrographs Na2MoO4 is the best performing inhibitor for the three cases. Our XPS measurements are in line with the proposed inhibitor mechanism by Vukasovich (1986), which is very complex and depends on whether the surface is active or passive to start with. In conclusion Na2MoO4 is a possible — and environmental-friendly — candidate to prevent corrosion of reinforcement steel.