Bentonite membranes are becoming increasingly the membrane of choice for below-ground tanking applications. We see this as a great step forward for the industry as bentonite membranes offer significant advantages for these challenging applications.

Auckland+Museum-3.jpgBelow-ground tanking applications require a long term solution, as the membrane can not be accessed once installed and covered. Furthermore, these applications are often difficult to manage, with water, mud, and a very real danger of the membrane being damaged during this phase of construction.

So why are Bentonite membranes becoming the preferred choice? Made of sodium bentonite, these membranes have the ability to swell to 16 times their dry volume. When confined, the pressure created by this swell is what provides a watertight seal. When you purchase a bentonite membrane, what you are buying is swell capacity, the greater the swell, the better the membrane will perform. A great benefit of bentonite membranes is that they have the ability to self heal when punctured, can swell to fill gaps caused by building movement and they can migrate into the pores of the substrate.

Auckland+Museum-1.jpg The problems associated with bentonite as a waterproofing membrane comes from contamination in the ground water. As contaminated water gets to the membrane, the swell ability can be drastically reduced thereby affecting the membranes performance. This process is known as ‘cationic exchange', whereby over time the sodium bentonite is converted, in the presence of contaminants, to calcium bentonite. The calcium form of bentonite only swells 4 times its dry volume.

Our exciting and unique pre-hydrated bentonite membrane is the only membrane of its type. As a pre-hydrated membrane, it is formed under vacuum extrusion in a patented process that gives it resistance to contamination and ensures a very high density of bentonite - which after all, is what you are buying! Ongoing non-destructive testing confirms the long-term contamination resistance of our rawMAT membrane.

Harbour+Residences.jpg Furthermore, unlike the dry bentonite systems, the rawMAT does not have to be contained within a heavy geotextile, allowing the bentonite to migrate in to the area being waterproofed. This prevents the possibility of water tracking behind the membrane and ensures the bentonite migrates right into the concrete substrate filling all pores, cracks and voids. Without this geotextile fabric, the rawMAT pre-hydrated bentonite also allows bentonite-to-bentonite contact at each lap joint giving greater lap integrity.

Finally, being pre-hydrated, the bentonite is plasticene like, so no bentonite is lost when detailing the membrane. Pre-hydrated bentonite and it's waterproofing capabilities truly has revolutionised the marketplace, the benefits are unquestionable in every facet from specification through to installation - Waterproofing Systems are proud to be the suppliers of the only pre-hydrated system available in New Zealand, rawMAT.

Rawmat Pre-hydrated Bentonite is simple to install.

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