Influence of detection methods on chloride threshold value for the corrosion of steel reinforcement

The aim of this study is to evaluate the influence of depassivation detection methods on chloride threshold value for the corrosion of steel reinforcement in a concrete. The detection methods of depasstivating steel reinforcement have been examined including electrochemical impedance spectra (EIS), potentiodynamic polarization (PP) in a simulated concrete pore solution and half-cell potential, linear polarization (LP) and electrochemical impedance spectra (EIS) in the concrete contaminated by chloride ions. The results have indicated that in a saturated Ca(OH)2 solution, the chloride threshold value for the corrosion of steel reinforcement concluded by the potentiodynamic polarization is 0.02 mol/L, which is identical with that decided by EIS. However, in the chloride contaminated concrete, no agreement among the chloride threshold values determined by the three detection methods mentioned above can be found. The range of the values decided by half-cell potential is relatively lower than those by the others, besides, the highest values have been obtained by EIS.