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| A multiscale prediction of effective diffusion coefficient of chloride ion in hardened cement paste |
| Jiangsu Key Laboratory of Construction Materials, Southeast University, Nanjing, Jiangsu 211189, China) |
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Abstract Based on the complex microstructure with a multiscale pore structure formed from the initial cement grains hydrate, the hardened cement paste was characterized into three-scale from down to up, C-S-H gel, hydrated products of cement and skeleton of hardened cement paste. Different homogenization models were used to predict diffusion coefficient of chloride ion and all inclusions were considered as sphere at different scale. According to multi-scale transition theory, the output parameters of low scale were considered as input parameters of higher scale. Based on the multi-scale transition theory, the quantitative relationship between the microstructure of hardened cement paste and macroscopic transport behavior of chloride ion in hardened cement paste was built for different scales one by one. By rapid chloride migration method, the diffusion coefficient of chloride ion was measured for the hardened cement paste with different ratio of water to cement of 0.23, 0.25 and 0.53. The proposed prediction was verified by the measured diffusion coefficient and reported value. The results show that predicted values of diffusion coefficient of chloride ion are consistent with experiment results, and that the different homogenization models at the different scale are reasonable.
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2011, Vol. 32 
