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Volclay Waterstoppage


Key Features

When wet, Waterstoppage forms into a dense, low permeable material that combines with the sodium bentonite in the Volclay System products to form a seamless waterproofing membrane.

Volclay Waterstoppage is used to fill cavities and voids in the substrate prior to installing the main bentonite waterproofing course. It is also used to seal around slab penetrations to form a continuous waterproofing system.

Volclay Waterstoppage is chemically treated, granular sodium bentonite used as a detailing accessory product for Volclay Waterproofing Systems.

A fillet of Waterstoppage can be poured at the footing/wall junction to provide additional waterproofing protection. A 3 mm thick layer of Waterstoppage is also applied to the top of tunnels and earth-covered roofs prior to the main Volclay waterproofing material course.

Mineralogical composition of Waterstoppage is a minimum 90% Montmorillonite with a maximum 10% native sediments and unaltered volcanic ash. Typical sieve analysis is 90% through a 20 mesh sieve and 10% through a 200 mesh sieve. Free swell rating of Waterstoppage is: two grams sifted into de-ionised water swells to occupy a minimum volume of 16cc.



  • Waterstoppage should not be applied in standing water or during precipitation.
  • Waterstoppage is intended for below-grade waterproofing applications.
  • Product requires proper confinement.
  • Confining soils should be compacted to a minimum 85% Modified Proctor density.
  • Waterstoppage is not an expansion joint sealant.