Diffusion des gaz dans les ciments

ABSTRACT This paper presents an experimental study of gas diffusion through cement pastes (CEM I and CEM V). First, the impact of Relative Humidity (RH) on gas diffusion is investigated by performing tests on samples pre-conditioned in specific atmospheric conditions (dry, 55%, 70%, 82%, 93% and 100% RH) by means of saline solutions. The results obtained with hydrogen show the important evolution of gas diffusion coefficients with the water saturation. Second, diffusion tests at different total pressures and with different gas mixtures (hydrogen—nitrogen and xenon—nitrogen) are performed to study the nature of gas diffusion in cementitious materials. Results demonstrate that gas diffusion in the tested cement pastes is controlled by Knudsen diffusion rather than by ordinary diffusion.