Semi-permeable membrane behaviour of conventional and enhanced Geosynthetic Clay Liners

The semipermeable membrane behavior of conventional and enhanced Geosynthetic Clay Liners (GCLs) is viewed with great interest in pollutant containment applications, as the consequent reduction of diffusive flow and the onset of chemical osmosis improves the containment properties. In this context, an experimental apparatus was developed to characterize the semipermeable membrane behavior of GCLs. Preliminary results were obtained on conventional GCLs and a Dense PreHydrated and polymer-enhanced (DPH) GCL. The measured values of the chemico-osmotic efficiency coefficient ω are comparable with literature data. In addition, owing to the possibility of monitoring the total vertical stress, the equipment allows determining the at the same time the swelling coefficient ω ̅. In this way, a complete picture of the behavior of the charged porous medium in response to chemical exposure is obtained and it is possible to determine on the same specimen the relevant parameters for the application of advanced theoretical models of chemical-osmotic phenomena in clays and GCLs.