Effect of sample thickness on laboratory determination of gas permeability of buffer material

Permeability of gases through geomaterials are critical in areas like landfill cover design, buffer material characterization in deep geological repositories for radioactive waste containment, geosequestration of greenhouse gases, oil and gas recovery. In general, there are two types of laboratory methods for determination of gas permeability of geomaterials, such as steady-state and transient or pressure decay methods. In all these methods, the sample thickness that needs to be considered is important for accurate estimation of gas permeability characteristics. In view of this, the present study discusses the effect of sample thickness on the laboratory determination of gas permeation through geomaterials. A permeability apparatus has been developed for evaluating the gas permeability characteristics of geomaterials over a range of compaction state, based on the concept of pressure decay. Further, the experiments are conducted at different sample thicknesses along the standard Proctor compaction curve and the effect of sample thickness on gas permeability has been evaluated.