ABSTRACT:

Geosynthetic clay liners (GCL) are known to have the ability to seal or reduce local leaks due to accidental puncture. The ability of self-healing must be studied in accordance to GCL environment, mainly the materials which constitute support and confining layers, and the hydraulic head above the defect. We present in this paper the results of in situ and laboratory experiments. To characterise the self-healing potential on a real job site, we have made artificial defects above small lysimeters allowing the determination of leak flow. The defects consist in various open and closed holes. This experiment has been completed by laboratory tests with artificial round defects. The tests allow to qualify and quantify the self-healing of several types of GCL. The experiments, described in this paper, have shown that the defects including the tool have logically the ability to seal the void around the tool. The healing kinetics of open holes show that a time of about 15 days is necessary to totally heal the defect, in the laboratory and in situ. With the hard boundary conditions we have applied, the tests have shown that the self-healing capacity is about 30 mm diameter for a low hydraulic head. The critical hydraulic heads are higher than those noticed in the cover of waste disposal (more than 1 m).

INTRODUCTION

The swelling ability of the bentonite, which is used in the geosynthetic clay liners (GCL), gives them a self-healing ability. This allows sealing or reducing local leaks due to accidental puncture. The self-healing ability has to be examined in the real field conditions of the GCL and particularly the support and confining materials, and the hydraulic head. In this paper, the results obtained in the Montlandon landfill configuration are described.

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