Fabric studies on contaminated mineral layers in composite liners

The fabric of mineral liner materials that had been exposed to organic compounds over a 12-year period was investigated as part of a wider research project. Macromorphological and micromorphological changes in the fabric were identified using computed tomography and polarisation microscopy. Special care was taken to ensure artefact free sampling and sample preparation, in particular, the drying method used, has a substantial influence on the quality of the thin sections. Fabric changes due to contaminant permeation over several years are, by and large, relatively small and their intensity is material specific. Silty clay CML1, in particular, contains a somewhat greater number of fissures and voids in comparison with the original material. The superposition of various processes in both test procedures and sample preparation may lead to fabric changes which can impede interpretation of the results. (C) 2002 Elsevier Science B.V. All rights reserved.