2019 Volume 75 Issue 4 Pages 239-250
Steel bars in concrete structures usually maintain a passivation state due to high pH in the concrete pore solution. However, it is known that the passivation film of a steel bar in concrete is destroyed by chloride attack in a marine environment. In the past studies, the condition of passivation film break down is defined by the the ratio of chloride ion concentration to hydroxide ion concentration when the passive film breaks, but this value varies depending on each researcher. In this paper, the theoretical model of passivation film break down was constructed based on point defect dynamics and it was suggested that the condition of the passivation film break down was influenced by a steel bar potential. From the experiment results, it was found that the relationship between the steel bar potential and the the ratio of chloride ion concentration to hydroxide ion concentration when the passive film breaks is an exponential relation. Therefore, it is estimated that the difference of the steel bar potential was the cause of value varies depending on each researcher.