Time-Dependency in the Corrosion Process of Reinforced Concrete Subjected to a Chloride Solution

Abstract

The corrosion of steel in reinforced concrete exposed to marine environments or winter de-icing poses a significant threat. However, evaluation of it is challenging due to variables such as environmental conditions and concrete properties. Many studies in concrete engineering have introduced a performance-based approach, evaluating structures with experimental data by considering the environmental conditions. Electrochemical techniques, including half-cell potential (HP), electrochemical impedance spectroscopy (EIS), and galvanostatic pulse (GP), are widely used for studying steel corrosion in concrete. Despite the widespread use, corrosion measurements have still limitations due to ambiguous impedance results from concrete presence, equipment sensitivity, and analysis flexibility. The corrosion of steel in chloride-laden concrete was assessed in well-controlled laboratory conditions using EIS and GP before field application. The results showed that measured values for corrosion parameters were consistent with each other (within 10% discrepancy). Corrosion initiation times varied from 171 to 319 days depending on the techniques, the differences attributed to measurement periods, and the condition of the steel. In addition, it was confirmed that the corrosion potential for HP was significantly correlated with the time constant for GP. This study demonstrated these techniques to improve both the understanding of the corrosion process and the accuracy of the calculated corrosion rate.

Keywords

• electrochemical impedance spectroscopy
• galvanostatic pulse technique
• chloride
• steel
• corrosion