RIW Structureseal is a bentonite sheet waterproofing composite of high swelling Sodium Bentonite encapsulated between a non-woven and woven geotextile. A needle-punch process interlocks the geotextiles together forming an extremely strong composite that maintains a consistent layer of Bentonite, as well as protecting it from inclement weather and construction related damage. When wetted, unconfined Bentonite can swell up to 15 times its dry volume. When confined under pressure within a structure the swelling is controlled, forming a dense, monolithic, impervious bentonite sheet waterproofing membrane.