Time-varying analytical model and mesoscopic numerical simulation of chloride ion diffusion in prestressed concrete cylinder pipe

Abstract

In this paper, a time-varying analytical model for chloride ion diffusion in Prestressed Concrete Cylinder Pipe (PCCP) protective layer is established based on the separation of variables method and Bessel function. The model takes into account factors such as steam curing, pipe radius, curing age, and exposure time. Meanwhile, the mesoscopic numerical simulation is conducted on the chloride ion diffusion behavior in the PCCP protective layer, and the effects of aggregate content, interfacial transition zone (ITZ) volume fraction, and ITZ chloride ion diffusion coefficient on chloride ion diffusion are analyzed. Results show that the aggregate has inhibitory effect on the diffusion process of chloride ions, without considering the influence of ITZ. As the aggregate content increases, the average depth of chloride ion diffusion decreases linearly. In the event of both the influence of aggregate content and ITZ are considered, there is a competitive relationship between the two. The larger the diffusion coefficient of chloride ions in ITZ, the larger the average diffusion depth of chloride ions is. In addition, the correctness of the numerical model and analytical model is compared and verified by combining their calculation results. Compared with traditional chloride ion diffusion models, the smaller the pipe diameter, the more accurately the chloride ion diffusion law can be reflected by the analytical model.