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Microstructure-based modelling of transport properties in non-saturated cementitious materials
Transport properties (e.g. permeability and diffusivity) of cementitious materials are usually considered as the main indicators for durability assessment and service life prediction of reinforced concrete structures. In practice, concrete is rarely saturated. Therefore, it is not only of scientific interest but of practical importance to study transport properties in non-saturated cementitious materials. In principle, an ideal model for transport properties should account for the 3D microstructure, especially the pore structure of cementitious materials. This study presents an integrated modelling scheme to estimate the transport properties of cementitious materials with various saturation levels based on their microstructures. The 3D microstructure of cement paste is obtained from high-resolution X-ray computed microtomography. An in-house code based on single-phase and multiphase lattice Boltzmann models is developed and used to simulate the moisture distribution, water permeability and ionic diffusivity of cement paste with different curing ages. Afterwards, the effects of moisture content and microstructure of cement paste on its permeability and ionic diffusivity are investigated in a quantitative manner. The results indicate that the moisture distribution, permeability and ionic diffusivity of non-saturated cement paste significantly depend on its 3D microstructure, in particular effective porosity. A unique relationship between transport properties and effective porosity can be found. The simulated results show a good agreement with experimental data. The proposed modelling scheme provides an effective tool to predict the transport properties in non-saturated cementitious materials. Keywords: Cement paste, microstructure, permeability, diffusivity, X-ray computed tomography.
Microstructure-based modelling of transport properties in non-saturated cementitious materials
Transport properties (e.g. permeability and diffusivity) of cementitious materials are usually considered as the main indicators for durability assessment and service life prediction of reinforced concrete structures. In practice, concrete is rarely saturated. Therefore, it is not only of scientific interest but of practical importance to study transport properties in non-saturated cementitious materials. In principle, an ideal model for transport properties should account for the 3D microstructure, especially the pore structure of cementitious materials. This study presents an integrated modelling scheme to estimate the transport properties of cementitious materials with various saturation levels based on their microstructures. The 3D microstructure of cement paste is obtained from high-resolution X-ray computed microtomography. An in-house code based on single-phase and multiphase lattice Boltzmann models is developed and used to simulate the moisture distribution, water permeability and ionic diffusivity of cement paste with different curing ages. Afterwards, the effects of moisture content and microstructure of cement paste on its permeability and ionic diffusivity are investigated in a quantitative manner. The results indicate that the moisture distribution, permeability and ionic diffusivity of non-saturated cement paste significantly depend on its 3D microstructure, in particular effective porosity. A unique relationship between transport properties and effective porosity can be found. The simulated results show a good agreement with experimental data. The proposed modelling scheme provides an effective tool to predict the transport properties in non-saturated cementitious materials. Keywords: Cement paste, microstructure, permeability, diffusivity, X-ray computed tomography.
Microstructure-based modelling of transport properties in non-saturated cementitious materials
Zhang, M (author) / Bai, Yun / Zhang, Wensheng
2016-09-24
In: Bai, Yun and Zhang, Wensheng, (eds.) Proceedings of the International Workshop on Innovation in Low-carbon Cement & Concrete Technology 21-24 September 2016, University College London, UK. (2016)
Paper
Electronic Resource
English
Experimental studies of ion transport in cementitious materials under partially saturated conditions
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