Gas permeability of compacted bentonite considering Klinkenberg effect

The gas permeability of compacted GMZ bentonite is studied using the triaxial gas permeameter. It is found that the Klinkenberg effect exists when the gas permeability is lower than 10^-14 m². A power relationship is observed between the Klinkenberg slippage factor and the ratio of the Klinkenberg permeability to the air-filled porosity. The relationship is independent on dry density and water content, and is almost identical with the Klinkenberg model. In the double-log scales, there is a linear relationship between the Klinkenberg permeability and the air-filled porosity, of which the slope is almost independent on water content. Based on the test results, a model for unsaturated gas permeability is proposed, in which the Klinkenberg effect is taken into account.