Influence of Degree of Deterioration and Electrolyte Solution on Repair Effect of Realkalization for Reinforced Concrete

Electrochemical realkalization has been applied to many concrete structures deteriorated by carbonation of concrete. As the repair effect of this method, it has been reported that the pH value of the carbonated concrete recovered by the electrolysis reaction at the steel in concrete and the electro-osmosis of the electrolyte solution in the anode system set on the concrete surface. However, the protection effect of the realkalization against the steel corrosion in concrete has not been clarified enough. Therefore, this study investigated the steel corrosion behavior in concrete after the application of realkalization in the cases of different degree of deterioration and different kind of electrolyte solution by measuring content profiles of several sort of ions and electrochemical indicators for evaluating steel corrosion. As a result, the electrochemical removal of Cl- ions from carbonated concrete and the electrochemical penetration of K+ ions from the electrolyte solution into carbonated concrete were both promoted compared with the case of non-carbonated specimen. Moreover, the protection ratio calculated by the corroded area ratio of steel bars in the electrochemically treated specimens and non-treated specimens subjected to the cyclic drying and wetting storage for 400 days after the period of realkalization achieved around 80% regardless of the difference of the deterioration condition before applying realkalization. This paper is an extended and enhanced version of an earlier work under different title [Takahashi, H., Ueda, T., Nanasawa, A., Nakayama, K. and Tsukagoshi, M., (2020). "Repair effect of realkalization for reinforced concrete with different degree of deterioration." In: Proceedings of the 6th International Conference on Concrete Materials - Performance, Innovations, and Structural Implications (ConMat'20), Fukuoka, Japan 27-29 August 2020. Tokyo: Japan Concrete Institute, 1065-1075].