A numerical method for the chloride diffusivity in concrete with aggregate shape effect

Abstract

Owing to its importance in the durability assessment and design of reinforced concrete structures exposed to chloride-ladden environments, it is essential to determine the chloride diffusivity in concrete. This paper presents a numerical method for predicting the chloride diffusivity in concrete with aggregate shape effect. To reduce the number of elements, an equivalent aggregate model is constituted by modeling the aggregate as inclusion and the interfacial transition zone (ITZ) as matrix and the chloride diffusivity in equivalent aggregate is derived analytically. Based on the simulated mesostructure of concrete, the lattice model is applied to the analysis of chloride diffusion in concrete. In this analysis, the physical properties of each phase constituent are taken into account in the formation of element matrix of bar elements. After the validity of the developed numerical method is verified with two independent sets of experimental results, the effect of aggregate shape on the chloride diffusivity in concrete is evaluated in a quantitative manner. It is found that, when the aspect ratio of elliptical aggregate particles increases from 1 to 3, the chloride diffusivity in concrete decreases by 6.48%, 8.94%, and 10.67% for a given chloride diffusivity ratio of ITZ to cement paste at 2, 6, and 10, respectively. The paper concludes that the numerical method developed in the paper can predict the chloride diffusivity in concrete with an average relative error smaller than 7% for the two selected verification examples.