Performance-based Criteria for the Control of GCBs in Landfill Applications
Résumé
While geosynthetic clay barriers (GCBs) are commonly used in landfill applications, it is well known that their hydraulic properties may deteriorate over time as a result of ion exchange following contact with various types of fluids (rainwater that has percolated through a landfill cover, landfill leachate, etc.). The potential for evolution of GCB hydraulic properties is typically assessed using oedopermeameter (oedometer permeability tests), but such tests are very timeconsuming and there is therefore a need for criteria that can be tested in a rapid and cost-effective fashion in order to provide information regarding the adequacy of a given product for a given application. The ongoing LIXAR2 project described herein aims at identifying such criteria and assessing to what extent they correlate with the results of oedopermeameter tests. This paper describes the project and presents some of the findings available to date. A preliminary selection of criteria includes: cation exchange capacity (CEC), proportion of smectite (which was found to be strongly correlated to CEC), proportion of exchange-site occupation by sodium, calcium carbonate content, free swelling capacity and carbon and oxygen isotope fractionation in the carbonate phase of the bentonite.