Study on Effectiveness of Electrochemical Re-Alkalization in Concrete

Abstract

Electrochemical Re-alkalization (ER) is a method of regaining concrete alkalinity which is lost by carbonation reaction. The steel reinforcement corrosion induced by carbonation and chloride can be controlled by a non-destructive alternative method based on the application of an electric field to the steel-concrete system by an external anode. Reinforced concrete cubes were casted using the OPC (Ordinary Portland Cement) with a water cement ratio of 0.45. Cathodic polarization measurement test were conducted and the current flow was monitored for different electrolyte such as saturated Ca(OH)2, saturated Ca(OH)2 solution+0.1 M CaCO3 and saturated Ca(OH)2+Cement extracted solution. The reinforced concrete cubes were treated with dilute HCl to simulate the degraded concrete and subjected for electrochemical Re-alkalization treatment. The Re-alkalization treatment was applied for 3 days with a current density of 1 A/m² and the electrolyte filled in the containers with 0.1 M CaCO3 + saturated Ca(OH)2 solution and 0.1 M extracted cement solution + saturated Ca(OH)2 solution. The reinforcements (cathode) are connected to the negative terminal and the SS container is connected to the positive terminal of the power source. After the treatment is completed, the increase in alkalinity was observed by spraying Phenolphthalein indicator. The pH values of the treated concrete samples have increased pH above 12.5. The compression strength of the treated specimen shows higher gain of about 25%.