New numerical method for predicting chloride diffusivity of concrete considering the profiles of practical aggregates

This paper aims to develop a numerical method for predicting the chloride diffusivity of concrete with practical aggregates. Based on three key parameters describing the profile of aggregate i.e. shape, angularity, and texture, the practical aggregate models were established using Fourier series. By placing the generated aggregates in the simulation area with introducing the periodic boundary conditions, a more approaching to practical concrete mescostructure was modeled. In order to guarantee both the simulation accuracy and the operating efficiency of computer, the required pixel was determined. Based on Fick's first law, a solution for the chloride concentration gradient in heterogeneous media was derived in the Fourier space and an iterative algorithm was proposed to calculate the chloride diffusivity of concrete. Compared with the existing simulation methods, the advantages of this numerical method possessed unwanted complex mesh generation, smalle data storage, and simple computation. After comparison with the experimental results, the accuracy of the numerical scheme was verified. Finally, the effects of thickness of the interfacial transition zone (ITZ), aggregate content, shape, angularity, and surface texture on the chloride diffusivity were quantitatively evaluated. (c) 2021 Elsevier Ltd. All rights reserved.