Short for geosynthetic clay liner, it carries at least 3.6 kg/m2 (0.75 lb/ft2) of dry bentonite between two geotextiles, usually needlepunched together so the panel can carry shear on slopes. When the bentonite hydrates it swells into a very low-permeability layer that can stand in for a thick compacted clay liner. Overlaps are dressed with extra bentonite, and panels must be covered before rain can hydrate them.
Rain's coming at three, so no more GCL goes down unless the cover soil is right behind it.
A GCL that hydrates before it is confined swells unevenly and can lose bentonite at the overlaps, so most specs require same-day cover.
Also heard as
- geosynthetic clay liner
- bentonite mat
- clay blanket
Related terms
Swell index
Test of how much a sample of bentonite from a GCL swells in water, an indicator of its sealing quality.
Composite liner
Barrier made of a geomembrane in direct contact with a low-permeability soil or GCL layer beneath it.
Overlap
Width by which neighboring rolls of geotextile, geogrid or GCL lie over one another to keep a continuous layer.
Geomembrane
Low-permeability polymer sheet used as a liquid or gas barrier in liners, covers, ponds and tunnels.