Influence of chloride salt type on threshold level of reinforcement corrosion in simulated concrete pore solutions

The objective of this study is to examine the influence of chloride salt type on the threshold level for the corrosion of steel reinforcement in concrete. The experiment was carried out in two kinds of simulated concrete pore solutions, i.e. saturated Ca(OH)2 solution and cement extract. KCl, NaCl, CaCl2 and MgCl2 were chosen as the sources of chloride to corrode the steel reinforcement. The initiation of pitting corrosion was detected by combining of the open-circuit potential (Ecorr) with corrosion current density (Icorr), which was measured by electrochemical impedance spectroscopy (EIS). It has been found that the threshold level for the chloride salts with a same valent cation is identical in two solutions. However, the threshold level is changed with the cation valence of chloride salts, and the actual effect depends on the solutions.

► We examine the effect of chloride salt type on the threshold level.
► The threshold level is changed with the cation valence of chloride salts.
► The corrosion initiation can be identified by the sudden shift of Ecorr and Icorr.
► The cement extract is more suitable to simulate the concrete pore solution.