Gérard Didier

Gas permeability of geosynthetic clay liners

Abstract Series of gas permeability tests were performed on partially saturated needle-punched geosynthetic clay liners (GCLs) with nitrogen (N2) as the gas permeant medium. The hydration procedure was found to have a strong influence on the gas permeability of the GCLs. For the range of overburden pressures considered in the present investigation, a reasonable linear relationship on a linear-log scale has been observed between the permeability and the volumetric water content. A decrease of around 1 to 1.5 order of magnitude in the permeability of a granular bentonite type of GCL and about 2 to 3 order of magnitude in the permeability of a powder bentonite type of GCL have been observed for the range of volumetric water content studied (46%

Field evaluation of hydraulic performances of geosynthetic clay liners by small and large-scale tests

Abstract This paper describes some devices to assess hydraulic performances of geosynthetic clay liners and presents the results of field tests in different design configurations. Some large- and small-scale experiments are presented hereby in order to characterise these products under real condition of solicitations. This approach contrasts with traditional laboratory tests performed for construction quality management. Three main methods are presented. The first method consists of a field hydraulic conductivity test comparable to those made for clay liners. This short-term/short-scale device is adapted for thin liners mainly for quality control purposes. The second method was developed to follow quite long-term performances of GCL against water intake. A last method, based on lysimeter technology, allows a long-term and large-scale monitoring of GCLs with leakage collecting system. Many results obtained from field experimentation managed in France are presented and commented.