Modeling of Chloride Ions Diffusion in Cracked Concrete

In the saline environment, chloride ions diffusion depth in concrete is very important for predicting the service life of concrete structures. Moreover, concrete structures are not always crack-free. Cracks with different widths and depths will reduce the cover thickness and accelerate the migration of chloride ions. So, it's significant to develop a model to predict the chloride diffusion depth in cracked concrete. In this research, the whole chloride diffusion process was divided into two parts: chloride diffusion in sound concrete and in crack. The solution concentration gradient existed in the crack obviously, and it changed the chloride concentration along the crack surface continually. Considering four factors that will influence the chloride diffusion in sound concrete, the diffusion model based on Fick's second law was modified. And a FEM analysis on chloride diffusion in cracked concrete was performed with the new model in ANSYS. A good agreement can be found in comparison the numerical solution with test results. It proves that the new mathematic model is within a good accuracy in predicting the chloride diffusion depth in cracked concrete.