2011 Volume 67 Issue 3 Pages 374-383
A new model was proposed to estimate effective diffusion coefficients of moisture under the internal vaporization condition. The proposed model assumed a two-layer model of dried and saturated region inside the porous sample. The model is formulized by utilizing the relative relationship of the results of isothermal thermo-gravimetric analysis obtained from the saturated porous sample and the free water in liquid condition. The present model was applied to the measurement results of hardened cement pastes with a variety of types of water cement ratio (W/C), resulting in effective diffusion coefficients being estimated ranging from 5.31*10-6 to 8.99*10-6 [m2/s] when W/C was 0.3 to 0.5.
