Multi-scale Modeling of the Effective Chloride Ion Diffusion Coefficient in Cement-based Composite Materials  

作　　者：孙国文 孙伟 

机构地区：[1]Jiangsu Key Laboratory of Construction Materials,Southeast University [2]School of Materials Science and Engineering,Shijiazhuang Tiedao University

出　　处：《Journal of Wuhan University of Technology(Materials Science)》2012年第2期364-373,共10页武汉理工大学学报（材料科学英文版）

基　　金：Funded by the National Basic Research Program of China (No.2009CB623203);the National High-Tech R&D Program of China (No.2008AA030794);the Postgraduates Research Innovation in University of Jiangsu Province in China (No.CX10B-064Z)

摘　　要：N-layered spherical inclusions model was used to calculate the effective diffusion coefficient of chloride ion in cement-based materials by using multi-scale method and then to investigate the relationship between the diffusivity and the microstructure of cement-basted materials where the microstructure included the interfacial transition zone （ITZ） between the aggregates and the bulk cement pastes as well as the microstructure of the bulk cement paste itself. For the convenience of applications, the mortar and concrete were considered as a four-phase spherical model, consisting of cement continuous phase, dispersed aggregates phase, interface transition zone and their homogenized effective medium phase. A general effective medium equation was established to calculate the diffusion coefficient of the hardened cement paste by considering the microstructure. During calculation, the tortuosity （n） and constrictivity factors （Ds/Do） of pore in the hardened pastes are n^3.2, Ds/Do=l.Ox 10-4 respectively from the test data. The calculated results using the n-layered spherical inclusions model are in good agreement with the experimental results; The effective diffusion coefficient of ITZ is 12 times that of the bulk cement for mortar and 17 times for concrete due to the difference between particle size distribution and the volume fraction of aggregates in mortar and concrete.N-layered spherical inclusions model was used to calculate the effective diffusion coefficient of chloride ion in cement-based materials by using multi-scale method and then to investigate the relationship between the diffusivity and the microstructure of cement-basted materials where the microstructure included the interfacial transition zone （ITZ） between the aggregates and the bulk cement pastes as well as the microstructure of the bulk cement paste itself. For the convenience of applications, the mortar and concrete were considered as a four-phase spherical model, consisting of cement continuous phase, dispersed aggregates phase, interface transition zone and their homogenized effective medium phase. A general effective medium equation was established to calculate the diffusion coefficient of the hardened cement paste by considering the microstructure. During calculation, the tortuosity （n） and constrictivity factors （Ds/Do） of pore in the hardened pastes are n^3.2, Ds/Do=l.Ox 10-4 respectively from the test data. The calculated results using the n-layered spherical inclusions model are in good agreement with the experimental results; The effective diffusion coefficient of ITZ is 12 times that of the bulk cement for mortar and 17 times for concrete due to the difference between particle size distribution and the volume fraction of aggregates in mortar and concrete.

关 键 词：multiscale chloride diffusion coefficient cement-based composite materials generaleffective medium theory composite spheres model MICROSTRUCTURE 

分 类 号：TU528[建筑科学—建筑技术科学]