TY - JOUR
T1 - Moisture diffusion in cementitious materials Moisture capacity and diffusivity
AU - Xi, Yunping
AU - Bažant, Zdenňek P.
AU - Molina, Larissa
AU - Jennings, Hamlin M.
N1 - Funding Information:
The theoretical part of the present research was supported under NSF grant 0830-350-C802 to Northwestern University, and the test data analysis was supported by NSF Science & Technology Center for Advanced Cement-Based Materials at Northwestern University. L. Molina wishes to thank Swedish Cement and Concrete Institute (CBI), Stockholm, for supporting her one-year Visiting Research Associate appointment at Northwestern University.
Copyright:
Copyright 2018 Elsevier B.V., All rights reserved.
PY - 1994/11
Y1 - 1994/11
N2 - Based on a model by Bažant and Najjar, and using a new model for adsorption isotherms, moisture capacity and diffusivity of concrete are analyzed. The moisture capacity, obtained as a derivative of the ] adsorption isotherm, first drops as the humidity increases from zero, then levels off as a consuant, and finally again increases when the humidity approaches saturation, regardless of the age, cement type, temperature, and water:cement ratio. The well-known diffusion mechanisms,including the ordinary diffusion, Knudsen diffusion, and surface diffusion, are analyzed and the diffusion in concrete is treated as a combination of these mechanisms. An improved formula for the dependence of diffusivity on pore humidity is proposed. The improved model for moisture diffusion is found to give satisfactory diffusion profiles and long-term drying predictions. The model is suited for incorporation into finite element programs for shrinkage and creep effects in concrete structures.
AB - Based on a model by Bažant and Najjar, and using a new model for adsorption isotherms, moisture capacity and diffusivity of concrete are analyzed. The moisture capacity, obtained as a derivative of the ] adsorption isotherm, first drops as the humidity increases from zero, then levels off as a consuant, and finally again increases when the humidity approaches saturation, regardless of the age, cement type, temperature, and water:cement ratio. The well-known diffusion mechanisms,including the ordinary diffusion, Knudsen diffusion, and surface diffusion, are analyzed and the diffusion in concrete is treated as a combination of these mechanisms. An improved formula for the dependence of diffusivity on pore humidity is proposed. The improved model for moisture diffusion is found to give satisfactory diffusion profiles and long-term drying predictions. The model is suited for incorporation into finite element programs for shrinkage and creep effects in concrete structures.
KW - Adsorption
KW - Concrete
KW - Hardened cement Moisture diffusion
KW - Moisture effects
KW - Permeability
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U2 - 10.1016/1065-7355(94)90034-5
DO - 10.1016/1065-7355(94)90034-5
M3 - Article
AN - SCOPUS:0028549641
VL - 1
SP - 258
EP - 266
JO - Cement and Concrete Research
JF - Cement and Concrete Research
SN - 0008-8846
IS - 6
ER -