"LabRat" wrote in message
Bentonite is also used to plug holes drilled for seismic exploration.
Swells up and helps focus the blast in a downward direction. Nothing
like walking around with a couple of kilos of GeoGel, (high explosive) in
the pockets of your coveralls and blasting caps in your shirt pocket, to
wake you up in the morning. bg


It's also used for "slurry walls" whereby a trench excavation is filled with
a bentonite slurry. The bentonite seals the adjacent soil, and the
hydrostatic pressure helps keep the trench walls from collapsing.

Joe F.