Numerical Analysis on Freezing Rate and Chloride Transport in Concrete Subjected to Freeze‒Thaw Cycles

The durability problem of concrete structures is severe in deicing salt and marine areas. The coarsen of pore structure caused by freeze‒thaw cycles (FTCs) can promote chloride transport. The pore solution can freeze into ice during the decrease of freezing temperature and consequently block chloride transport. Also, the change of chloride concentration affects the phase transition of pore solution and then chloride transport. This paper proposed a model considering freezing rate of porous solution during FTCs to analyze the effect of icing on the ionic transport. A multi-phase numerical model for coupling the binary actions of freeze‒thaw and chloride transport was proposed and also verified via multiple third-party experiments. The results indicate that the freezing rate and chloride concentration increase with the increase of FTCs, and the temperature and duration of FTC both have an impact on the chloride transport. In addition, the increase of solution concentration also accelerates the chloride transport and the concrete structure deterioration although it is conducive to the decrease of pore freezing temperature and freezing rate.