A Brownian motion simulation for the chloride diffusivity of concrete

• Published in: Construction & building materials 2016-09, Vol.122, p.478-487
• Main Authors: Zheng, Jian-Jun, Zhang, Cong-Yan, Sun, Lin-Zhu, Zhou, Xin-Zhu
• Format: Article
• Language: English
• Subjects: Analysis; Brownian motion simulation; Chloride diffusivity; Concrete; Mechanical properties; Thermal diffusivity
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2016.06.094

•A Brownian motion simulation is developed for the chloride diffusivity of concrete.•The cumulative distribution function for aggregates is derived analytically.•The validity of the simulation method is verified with experimental results. The purpose of this paper is to present a Brownian motion simulation for the chloride diffusivity of concrete. According to stereological theory, the probability density function and cumulative distribution function for the circular aggregates in terms of the number of aggregates are derived. By coating each aggregate with an interfacial transition zone (ITZ) layer of equal thickness, concrete is then reduced to a two-phase composite material, composed of a bulk cement paste and equivalent aggregates. The equivalent ITZ thickness and the chloride diffusivity of each equivalent aggregate are formulated in an analytical manner. The Brownian motion simulation is used to compute the chloride diffusivity of concrete. Finally, the validity of the numerical simulation is verified with two sets of experimental results and the effects of the aggregate area fraction, the chloride diffusivity of ITZ, and the ITZ thickness on the chloride diffusivity of concrete are evaluated in a quantitative manner. The paper concludes that the numerical simulation can predict the chloride diffusivity of concrete with an average relative error smaller than 6% for the two selected verification examples.