Numerical Scheme for Predicting Chloride Diffusivity of Concrete

Abstract

Owing to the lack of research for evaluating the effect of the aggregate profile on the chloride diffusivity of concrete, this paper presents a numerical scheme for predicting the chloride diffusivity of concrete with practical aggregates. Using Fourier series, practical aggregate models consisting of pixels are established. A computer simulation of the mesostructure of concrete with established aggregates is performed. A random-walk simulation for digitized media is introduced to solve the diffusion equation of chloride ions, and the chloride diffusivity of concrete is determined. To ensure both the simulation accuracy and the operating efficiency of the computer, the first-passage radius and the numbers of random walkers are determined. The accuracy of the numerical scheme is verified via a comparison with experimental results. Finally, the impact factors, e.g., the interfacial transition zone (ITZ) thickness and the aggregate content, shape, angularity, and surface texture, are quantitatively evaluated. The simulation results indicate that the chloride diffusivity is significantly affected by the ITZ thickness, aggregate content, and aggregate shape but is hardly affected by the angularity and surface texture of the aggregate.