RAWMAT® HDB pre-hydrated natural sodium bentonite membranes are manufactured by Rawell Environmental Ltd for use in a wide range of construction, industrial and environmental uses.

In Structural Waterproofing Applications the materials act as a barrier to the passage of water and vapour. The material is supplied in rolls 1m wide for ease of handling and 2m wide for maximum coverage and are quick and simple to install.

The RAWMAT® HDB membranes differ from traditional “peel and stick” or “torch applied” bitumen membranes in that they can be nailed to the structure they are applied to. Furthermore the swellable nature of the volcanic clay core enables them to withstand minor movement in the structure and maintain a waterproof seal. The natural sodium bentonite in RAWMAT® HDB membranes and RAWSEAL® waterstops is pre-hydrated with a patented polymer solution which provides a permanent protection to the ionic fingerprint of the clay protecting it from exchange and subsequent breakdown in ground contaminants, a drawback widely associated with other bentonite systems. As a result the RAWMAT® HDB will perform its function of waterproofing the structure to which it is applied for the life of that building.

A major advantage of the RAWMAT® HDB membranes is the sealing of the sheets at overlaps. The membranes, regardless of the product type, allow intimate self sealing joints at the overlap. The membranes can be used in almost all underslab applications regardless of complex penetration details, lift pits or piling.

No wicking of liquid occurs through the overlap or through the geotextile carrying fabrics. In addition the choice of the geotextile carriers ensures that a bentonite seal is created between the membrane and the structure to which it is applied, thus preventing the tracking of liquid in the unlikely event of the system being compromised. The plasticine like central core ensures that there is no movement of clay between the geotextiles in handling and no loss of the bentonite when the sheets are cut.

For vertical applications such as property line construction, sheet and secant pile construction and traditional in-situ designs, RAWMAT® HDB membranes and RAWSEAL® waterstops provide a fast and effective method of providing high security waterproofing. The swelling properties of the pre-hydrated High Density Bentonite enable it to accomodate irregular surfaces and substrates.

Installation is swift and is not weather dependent. The materials can be applied to "green" concrete and without the need for primers, adhesives or protection boards. The sheets are simply nailed to the concrete and are flexible enough to be easily sealed around corners and penetrations.

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