Short-term benefits of Cathodic Protection of steel in concrete
conference paper
Cathodic Protection (CP) of steel in concrete has been used over the past decades in order to increase the remaining service life of concrete infrastructure. CP involves the application of an electrical current to the corroding reinforcing bars, thus stopping and preventing further corrosion. The application of current on the reinforcing steel involves an alteration of the conditions inside corrosion pits that need further investigation. In this study, CP was applied to four concrete specimens, exposed separately to salt/dry cycles, carbonation or mixed-in chlorides, with actively corroding bars. Afterwards, such specimens were exposed to outdoor (unsheltered) environment until 2010. The four of them were subjected to CP at fixed voltage and the current density was monitored for 18 days. Significant changes were found during the first 24 hours of C P. It was found that the immediate current density was related to the corrosion rate before CP. Then, a steep decrease was observed during the first 4 to 8 hours, remaining stable afterwards. Destructive analysis and assessment of the deterioration of reinforcement was carried out once the CP period was finished. This included measurements of the size in pits and estimations of the volume loss. With the use of a previously proposed model, approximations of the pH inside corrosion pits were carried out, by relating the electrical charge, the neutralization of hydrogen and volume pit with results of pH ≈ 2-3. © 2012 Taylor & Francis Group.
Topics
TNO Identifier
446764
ISBN
9780415616225
Source title
4th International Conference on Concrete Repair, 26 September 2011 through 28 September 2011, Dresden
Pages
147-156
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