rawMAT Bentonite Tanking | Waterproofing Systems NZ

The rawMAT Pre-hydrated Bentonite system provides high level waterproofing protection to below ground structures in the most demanding situations.

The advantage of our pre-hydrated bentonite system is that the initial bentonite hydration occurs under factory controlled conditions. Unlike the dry bentonite systems, which are prone to shrinkage and cracking, the Rawmat Pre-hydrated bentonite is highly resistant to the effects of water contaminants. These contaminants induce cationic exchange in dry bentonite systems causing them to have a reduced swell, shrink and crack as the clay converts from sodium bentonite to the calcium form.

The advantages of rawMAT bentonite is that it can be installed directly onto compacted sub-bases, concrete substrates or applied to sacrificial shutters and steel piles. It also self-heals when damaged and can be installed on wet substrates. The rawMAT bentonite tanking system is the premier tanking system and used in high hydrostatic pressure situations.

How does bentonite work?

The natural sodium bentonite clay will absorb water and expand up to 16 times its dry volume when in contact with water. When confined, e.g. between the ground and the floor slab, this tendency to swell generates substantial swell pressures preventing the passage of water. When correctly installed, the rawMAT bentonite system acts as an effective hydrostatic seal. An important factor affecting the amount of swell achieved is the quality of water hydrating the bentonite.

Why you should use rawMAT pre-hydrated bentonite

Unlike dry bentonite systems the rawMAT bentonite membrane system is resistant to chemical degradation (cationic exchange), are easy to install and also have the ability to withstand minor movement in the structure.

Additionally the rawMAT bentonite system:

  • Can be installed on damp and uncured substrates, and in inclement weather
  • The bentonite requires no priming
  • The bentonite can be nailed to the substrate
  • Lose no bentonite when handling, folding or cutting the bentonite
  • The bentonite is highly resistant to chemicals and hydrocarbons
  • Are natural products with an indefinite life
  • The bentonite be installed onto a variety of substrates including; concrete, rock-face, compacted sub-base, shutters etc. Also onto uncured or wet substrates, in any weather
  • The bentonite will self heal when cut or damaged
  • Britisih Board of Agrément (BBA) Approved (Cert. No. 97/3337, 2nd Issue)

Installation Advantage of rawMAT bentonite

Joining two sheets of rawMAT bentonite could not be more simple.

The nature of rawMAT bentonite enables a self sealing joint to form at all laps without the need for the addition of bentonite between the joints.

The bentonite membrane can be simply trimmed and cut with a utility knife to fit around pipes, inlets, posts and other protrusions. rawMAT bentonite has a unique solid form which can be cut without any loss of bentonite, ensuring a secure seal in all cases. Furthermore, rawMAT bentonite can be installed on damp substrates.


Rawmat is a HDB (High Density Bentonite) the only prehydrated bentonite available in the world. Rawmat is also the only bentonite system which is 100% waterproof immediately during installation and the only bentonite system which remains permeable holds the swell pressure when in contact with salt water, petrol, diesel oil, landfill leachate, Ethylene Glycol and highly resistant to hydrocarbons making the system an exceptional a standalone bentonite system. There is no loose bentonite when cutting or folding Rawmat every lap is a direct bentonite to bentonite bond making the whole installed system a homogeneous membrane system no other bentonite system has this feature. Rawmat has a BBA (British Board of Agreement) and is accepted by all local consenting authorities.


Rawmat under expansion merges with and into the exposed face of the concrete substrate becoming part of the wall system preventing any water tracking down through the face of the wall something that cannot be avoided with all the alternative bentonite systems. Rawmat can be installed on green concrete directly onto compacted fill saving construction time. Rawmat prehydrated bentonite will have the life span of the life of the building providing protection the too structure against moisture ingress.

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Featured Projects


Specifier: Hulena Architects Brand/Product: rawMAT Type P Applicator: Auckland Waterproofing Size/Area: 2000m2 Region: Coatesville, Auckland

Detail Drawings

B-RAW00 - Lap Joint

b-RAW00 - Lap Joint.pdf

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