X-Ray Imaging of Desiccation Cracking Patterns in Geosynthetic Clay Liners

J.J. Potvin, G.A. Siemens, A. Kerr, W.A. Take

In the proceedings of: GEO2011: 64th Canadian Geotechnical Conference, 14th Pan-American Conference on Soil Mechanics and Geotechnical Engineering, 5th Pan-American Conference on Teaching and Learning of Geotechnical Engineering

Session: Geoenvironmental Engineering

ABSTRACT: A geosynthetic clay liner (GCL) is a low permeability layer that is often used as part of a composite liner in various hydraulic barrier applications, such as landfills. The GCL consists of bentonite, a high swelling clay, that is bonded to other geosynthetic layers by needle punched fibres or epoxy. After placement of the liner on a foundation soil, the bentonite must hydrate by absorbing water from the subsoil in order to achieve a homogeneous structure and its low hydraulic conductivity. However, if these GCLs subsequently lose moisture, the internal bentonite layer is susceptible to cracking due to an increase in matric suction. As long as the swelling properties of bentonite remain intact, these cracks have the potential to heal upon rehydration and the GCL will regain its low hydraulic conductivity. To investigate this cracking process, a sample of GCL was slowly dried to known target moisture contents and the sample was interrogated non-invasively for cracks using digital x-ray imaging technology. This paper describes the image processing techniques developed to quantify cracks in GCLs and provides preliminary fthe roll

RÉSUMÉ: Une géocomposite bentonitiques (GCB) est une couche à faible perméabilité qui est fréquemment utilisée comme revêtement composite dans des applications variées des barrières hydrauliques, telles que les décharges. La GCB est -ci est liée à d'autres couches de fibres géosynthétiques. Après le placement de la chemise géosynthétique sur un sol de fondation, la -sol, ce qui lui permet de parvenir à sa structure bentonite interne est sensible à la fissuration due à une augmentation de la succion matricielle. Si les propriétés de gonflement de la bentonite ne sont pas affectées et donc, demeurent malgré tout intacts, ces fissures générées par la entiel de se régénérer lors de la réhydratation. Cela dit, la GCB retrouvera sa faible fut examiné de façon non destructive des fissures en utilisant la technologie numérique d'imagerie à rayons X. Cet article traitera des techniques de traitement d'images mis au point autres, des résultats préliminaires sur les

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