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Bentoline is mined volcanic ash that fell millions of years ago and got laid in seams under the sea.

Being encapsulated between two layers of geotextile, when hydrated the particles expand and create an impermeable layer which is equivalent to 1m depth of puddled clay. Because of its swelling properties it is required to place a 300mm consolidation layer of soil over the Bentoline to confine it.



Suitable for canals, dams, reservoirs, lakes and land-fill capping sites.

Bentoline CL

For tunnels, piles and foundation protection.


  • An economic and environmentally sound alternative to synthetic liners or to bituminous products.
  • Dense and slim with high bond and shear strength.
  • Superior to conventional compacted/puddled clay lining
  • High puncture and tear resistance – the bentonite clay has a high swelling capacity and low permeability offering good system integrity.
  • Self-sealing.
  • Long-term protection against ground water seepage.


  • Mini rolls: 1.1m x 5m
  • Half rolls: 2.5m x 40m or 5m x 20m
  • Full roll: 5m x 40m

Project photos

Case Studies

The following projects involved Bentonite Geosynthetic Clay Liners