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Journal Article

Simple Analytical Solution for the Chloride Diffusivity of Cement Paste

TL;DR: In this article, a simple analytical solution for the chloride diffusivity of cement paste was presented, combining the percolation theory with the general effective medium approximation, and the analytical solution was verified with two independent sets of experimental data.
Abstract: A simple analytical solution for the chloride diffusivity of cement paste was presented.Cement paste was considered as a two-phase composite material,composed of the solid phase and pores.By combining the percolation theory with the general effective-medium approximation,the analytical solution for the chloride diffusivity of cement paste was derived.The validity of the proposed analytical solution was verified with two independent of sets of experimental data. Finally,the effects of the water/cement ratio and the degree of hydration on the chloride diffusivity of cement paste were evaluated in a quantitative manner. It was found that the chloride diffusivity of cement paste decreases with the increase of the degree of hydration,but increases with the increase of the water/cement ratio.
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Journal ArticleDOI
Guowen Sun1, Yunsheng Zhang1, Wei Sun1, Zhiyong Liu1, Cai-hui Wang1 
TL;DR: In this article, the N-layered spherical inclusion theory is applied to develop a multi-scale model to predict the effective diffusion coefficient of chloride ion in concrete, which treats concrete as four-phase composite materials consisting of matrix phase, aggregate phase, ITZ (interfacial transition zone) and their homogenization phase.

115 citations

Journal ArticleDOI
TL;DR: In this paper, a multi-scale model for quantifying the chloride effective diffusion coefficient of bulk cement paste (DClbcp) and concrete is proposed and the results are statistically equal with 95% confidence to the experimental values.

35 citations

Journal ArticleDOI
TL;DR: In this article, a multi-level micromechanical model is proposed to predict the diffusion coefficient of manufactured sand (MS) considering MS particle shape and limestone powder effects, which shows that MS mortar demonstrates the highest diffusion coefficient when MS particles are spherical.

29 citations

Journal ArticleDOI
TL;DR: Based on effective media theory, a predictive model, relating chloride diffusivity to the capillary pores, gel pores, tortuosity factor, and pore size distribution of hardened cement, is proposed in this paper.
Abstract: Based on effective media theory, a predictive model, relating chloride diffusivity to the capillary pores, gel pores, tortuosity factor, and pore size distribution of hardened cement, is proposed. To verify the proposed model, the diffusion coefficient of chloride ions, the degree of hydration, and peak radius of capillary pores of cement paste specimens were measured. The predicted results for chloride diffusivity were compared with published data. The results showed that the predicted chloride diffusivity of hardened cement paste was in good agreement with the experimental results. The effect of the evolution of pore structures in cement paste on chloride diffusivity could be deduced simultaneously using the proposed model.

24 citations

Journal ArticleDOI
TL;DR: In this paper, an analytical relation between porosity, pore diffusivity, and overall diffusivities of the cement paste is investigated, based on the resolution of the pore space as pore channels being oriented in all space directions.
Abstract: Chloride ingress into concrete is a major cause for material degradation, such as cracking due to corrosion-induced steel reinforcement expansion Corresponding transport processes encompass diffusion, convection, and migration, and their mathematical quantification as a function of the concrete composition remains an unrevealed enigma Approaching the problem step by step, we here concentrate on the diffusivity of cement paste, and how it follows from the microstructural features of the material and from the chloride diffusivity in the capillary pore spaces For this purpose, we employ advanced self-consistent homogenization theory as recently used for permeability upscaling, based on the resolution of the pore space as pore channels being oriented in all space directions, resulting in a quite compact analytical relation between porosity, pore diffusivity, and the overall diffusivity of the cement paste This relation is supported by experiments and reconfirms the pivotal role that layered water most probably plays for the reduction of the pore diffusivity, with respect to the diffusivity found under the chemical condition of a bulk solution

18 citations