Time-variant probabilistic assessment of corrosion initiation of marine concrete structures considering maximum phenomenon

Abstract

This study presents a new dual time-variant chloride diffusion model considering maximum phenomenon for concrete structures exposed to marine environment. The model is developed from the assumption that the concentration gradient is the sole or dominant driving force for chloride ingress in concrete, and both the chloride diffusion coefficient and peak chloride content are considered as time-variant. The applicability and accuracy of the developed model are verified by comparing the fitted and predicted chloride profiles with field data. Based on the developed model, time-variant probabilistic evaluation of corrosion initiation in a typical prestressed box girder located near coast is carried out. Results reveal that the maximum phenomenon has a significant effect on the prediction of the time to corrosion initiation. The results of sensitivity analysis indicate that the critical chloride content is the decisive parameter in the prediction of the corrosion initiation time, followed by the relative humidity, water-to-binder ratio, temperature, thickness of concrete cover, etc. Besides, the effects of the correlation between random variables and the distance from the coast on the time-variant probability of corrosion initiation are investigated. It is found that the correlation among random variables should be considered, and the effect of distance from the coast on the time-variant probability of corrosion initiation is sharply decreasing at a very short distance from the coast.