Sodium bentonite can swell many times its dry volume when hydrated, forming a dense, low-permeability gel. It is supplied in geotextile mats, cardboard panels and waterstop strips, and it must be confined by soil or concrete to work. It self-heals small punctures but can be weakened by salt water, contaminated groundwater or wetting before it is confined.
Bentonite mats got rained on before backfill, they've swelled and washed out at the laps.
Bentonite must stay dry until it is confined, so crews cover it at night and backfill or pour against it quickly.
Also heard as
- bentonite clay
- bentonite mat
- GCL
Related terms
Blindside
Waterproofing installed on the shoring or soil face before the wall is poured against it.
Waterstop
A strip cast into concrete joints to block water from traveling along the joint plane.
Hydrostatic pressure
Pressure from standing groundwater against a wall or slab, rising with the depth of water above that point.
Positive side
The face of a wall or slab that touches the water source, where waterproofing works best.