Electrochemical Healing Techniques for Concrete Reinforcement Restoration

Electrochemical chloride extraction (ECE) from a reinforced concrete structure may be accompanied with an electrochemical injection of healing agents (EICI) if such agents are positively charged and are able to migrate towards the activated reinforcement. Positive charge carrying nanoparticles or cationic corrosion inhibitors might be the proper choice. Organic substances with a positive charge and their salts are mostly such inhibitors. In this study, critical concentration of chlorides was investigated for fresh and carbonated concrete pore solution. Corrosion inhibition efficiency was evaluated by means of polarization resistance as a measure of corrosion rate. Sodium nitrite was taken as a reference corrosion inhibitor. As a second objective were migration tests. ECE and EICI were performed in order to test the migration ability of promising cation corrosion inhibitors, namely tetrabutylammonium bromide and tetrabutylphosphonium bromide. Concentration profile of the inhibitors and chlorides was investigated in the testing concrete blocks. The best results have been obtained for tetrabutylammonium bromide.