INFLUENCE OF CORROSION DEGREE OF REINFORCEMENT ON EFECTIVENESS OF REALKALISATION METHOD FOR TREATING CARBONATED CONCRETE STRUCTURES

The realkalisation treatment is one of the methods applied to recover the alkalinity conditions of cementitious matrix and, consequently, to meet the possible reinforcement repassivation without any significant destructive procedure to structure. This paper analyses the effectiveness of realkalisation on repassivation of reinforcements with different exposure times on carbonated media. For this purpose, concrete reinforcements with 6.3 mm core were immersed in saturated solution of calcium hydroxide, simulating the concrete porous network solution. After 17 days, these solutions were carbonated with a 5% CO2 mixture until reaching a pH close to 8,5. After starting the corrosion process, the cells remained in laboratory environment for 7, 28 and 90 days to meet different corrosion degrees. Afterwards, the carbonated solutions were realkalised by changing the solutions for new ones. Reinforcements were monitored throughout all these periods by electrochemical measurements using the linear polarization resistance technique. Electrochemical measurements show the moments in which reinforcements depassivated, as well as the moments in which they recovered or not the passivity condition. The longer exposure to carbonated media made difficult the reinforcement repassivation.