A Three-dimensional Numerical Modeling Method For Predicting The Chloride Diffusivity Of Concrete

Since there is an interfacial transition zone (ITZ) between aggregate particles and cement paste, concrete can be considered as a three-phase composite material composed of aggregate particles, cement paste and ITZ in predicting the chloride diffusivity of concrete. Thus, the chloride diffusivity of concrete is dependent, to a great extent, on the volume fractions of the three phase constituents, the chloride diffusivities of the individual phases and the interaction between them. Therefore, the study on the quantitative relationship between the chloride diffusivity and mesostructure of concrete will provide a theoretical basis for the optimisation design of concrete.Based on the similarity between chloride diffusion and heat conduction, a three-dimensional numerical modeling method is presented for predicting the chloride diffusivity of concrete. The validity of the proposed method is verified with two independent series of experimental results. Based on the numerical results, the effects of the maximum aggregate diameter, ITZ thickness, aggregate gradation and the chloride diffusivity of ITZ on the chloride diffusivity of concrete are evaluated in a quantitative manner. It is found that the chloride diffusivity of concrete increases with the increase of the thickness and chloride diffusivity of ITZ, but decreases by increasing the maximum aggregate diameter. It is also found that the aggregate gradation has a larger influence on the chloride diffusivity of concrete. The chloride diffusivity of concrete with ITZ cracks is analysed. The effects of the opening angle, ITZ thickness and maximum aggregate diameter on the chloride diffusivity of concrete with ITZ cracks are quantitatively evaluated. The conclusions made in this paper can provide some reference for the durability assess and design of reinforced concrete structures located in a chloride-laden environment.