Abstract: A method was devised for obtaining the activation energy for the viscous flow of a fluid through a porous medium and the method was applied to the flow of water through samples of Na-bentonite. The resulting activation energies were generally higher than the activation energy for the flow of pure water. The activation energy depended on the length of time the water was in contact with the clay and also on the particular sample. For any given sample, the water flow rate was negatively correlated with the activation energy, in accordance with theory.
To help interpret these results, data are presented on the tension of water in Na-bentonite suspensions at different intervals of time after stirring. The water tension was near zero immediately after stirring but increased gradually with time. Simultaneously the suspension gelled. Data also are presented on the specific volumes of water, the activation energies for ion movement, the diffusion coefficients of chloride salts and the unfrozen water at −5°C in Li-, Na- and K-bentonite. The activation energies for ion movement and the amounts of unfrozen water were positively correlated with the specific volumes of the water, whereas the diffusion coefficients of the chloride salts were negatively correlated with the specific volumes of the water. In each clay the specific volume of the water and the activation energy for ion movement were higher than those in normal water.
It is concluded that a water structure, which varies in extent with particle arrangement and the adsorbed cationic species, exists at the surface of clay particles. This structure bestows a high viscosity to the adsorbed water.