The 4th Asian Concrete Federation Symposium on Emerging Technologies for Structural Longevity (ACF2023- ETSL)

99 / 2022-04-21 09:31:28

Oxygen transportation into non-saturated concrete and induced corrosion of steel bar

Corrosion,crack,wire beam electrode (WBE),concrete,oxygen

This paper aims to study the oxygen transportation into concrete with 5-85%RH, and induced corrosion propagation behavior of reinforced bar. A novel custom-designed wire beam electrode (WBE) covered by mortar was applied to record the evolution of the corrosion current distribution and electrochemical impedance spectrum (EIS) results. The corrosion expansion stress was calculated based on the evolution of strain on inner surface of reinforcement. And the corrosion production of reinforcement in different oxygen concentration was detected by SEM. The results showed the oxygen diffusion coefficient of mortar increased with its W/B and RH. The WBE technique can effectively monitor the entire process of passivation and pitting corrosion, especially for the propagation behaviour of corrosion. The corrosion expansion stress increased with corrosion time and decreased due to crack of concrete. Pitting corrosion is the main form of initial corrosion that then propagates to surrounding positions and eventually evolves to the uniform corrosion of steel. Corrosion propagation of wire electrodes mainly determined by the chloride distribution, which changes with increasing crack width and prolonged erosion time.