Freeze-thaw action and chloride corrosion both have influences on the service life of reinforced concrete structures under northern marine environment. Based on the Fick’s second law, a model for chloride ion migration within concrete, in which the effect of time, temperature, humidity, chlorine binding capacity and the freeze-thaw damage effect had been taken into account, was established in this paper. The model was used to predict the corrosion life for the reinforced concrete piers of the Qingdao Bay Bridge. The results show that rebars inside concrete members have an obvious blocking effect on chloride ion migration. Chloride ions are likely to accumulate on the surface of the steel bar near the protective layer while concentration retardation appears on the surface of the steel bar far away from the protective layer. The peak chloride concentration in the corner region is higher than that in the non-corner region of a concrete member, and the peak values rise with the erosion time. The distribution of chloride concentration around the rebar in the inner corner of the member varies with the erosion time. At the beginning of the erosion, the peak chloride concentration occurs on the surface of the rebar perpendicular to the eroded surface, and then, it turns to appear at the diagonal of the two eroded surfaces. Compared the results in the non-salt freeze-thaw environment, the corrosion life of the concrete structure is dramatically reduced after a freeze-thaw cycle in salt environment, and the distinction of the corrosion life of the concrete component between the corner and non-corner areas also significantly increases.
Advances in Science and Technology of Water Resources
service life prediction