Bentonite Sheet Waterproofing
This information reflects our best understanding of product composition in 2021.
Bentonite sheet waterproofing membranes are comprised of a bentonite clay layer sandwiched between geotextile sheets and often laminated with a high density polyethylene (HDPE) film, though the HDPE layer is not always present. The geotextile...
Bentonite sheet waterproofing membranes are comprised of a bentonite clay layer sandwiched between geotextile sheets and often laminated with a high density polyethylene (HDPE) film, though the HDPE layer is not always present. The geotextile layers are most often comprised of one woven and one non-woven polyproylene sheet, though the geotextiles may also be made from other synthetic fibers such as polyester. Waterproofing is achieved through the absorptive and self-sealing properties of bentonite clay, which can absorb several times its weight in water and will expand and become impermeable when hydrated to fill punctures or tears in the sheet. The HDPE layer provides additional waterproofing and the polypropylene sheets protect the waterproofing membrane during installation and use. Naturally-occuring bentonite is most often used, though compounds such as polymer-modified bentonite may be used in limited situations. Bentonite sheet waterproofing may be used for waterproofing above- or below-grade horizontal and vertical surfaces and is often cited for use in blindside applications where waterproofing is applied before foundation substrates, such as concrete, are placed.