Influence of calcium ion in concrete pore solution on the passivation of galvanized steel bars

The addition of supplementary cementitious materials may affect the Ca2+ concentration and pH value of the concrete pore solutions. This work studied the influence of the calcium ion on the passivation of the galvanized steel bars in simulated concrete pore solutions with relatively low pH value of 12.5 and 13.15. The results showed that continuous protective layers were formed on the galvanized coating in the solutions with saturated Ca(OH)2 at pH 12.5 and solutions with either KOH or NaOH at pH 13.15. The passive film formed in the saturated Ca(OH)2 solution showed better protective properties than those in other solutions. In the solutions with lower concentrations of Ca2+ at pH 12.5, there was no obvious reaction and no protective layer was formed on the surface.