Preliminary test results on gas permeability of soils and geosynthetic clay liners

Abstract

The hydraulic permeability of soils is commonly determined by numerous testing methods that are currently available for laboratory and field measurements. However, the aforementioned test methods are not completely appropriate for the gas permeability measurements of soils. There is a growing interest in gas permeability determination mostly for environmental applications and also for geotechnical engineering in general. Special attention is paid to large quantities of biogas produced in landfills. Geosynthetic clay liners (GCLs) have already been recognised as a highly effective hydraulic barrier, but there has also been a growing interest in assessing the efficiency of GCLs as a gas barrier. The objective of this paper is to develop a simple method for gas permeability testing of GCL samples and bentonite in a triaxial device, comparable with the standard testing methods for hydraulic permeability determination. The first part of the testing procedure comprised eight samples of various soil types, in order to compare the obtained values with similar published test results – that is, to confirm the method. The paper highlights the advantages of the proposed method and suggests some guidelines for further research aimed at improving it.