Bentonite Proves Resistant to Drying Out and Cracking

Myth 1: Bentonite Dries Out

This one is perhaps the most misunderstood of all. Firstly, 'dry' bentonite has a 25% moisture content — it's actually very hard to dry bentonite out. So hard in fact, that it took BRANZ over three whole days (using an industrial oven set at over 200°C) to remove the moisture from a hydrated sample of Volclay Bentonite and return it to a granular state.

Interestingly, bentonite can be re-hydrated and dried an infinite number of times without losing its original swelling capacity. It can similarly be frozen and thawed repeatedly without losing its ability to swell.

For more information, please read over Volclay's Branz appraisal.

Myth 2: Bentonite Cracks

The sodium bentonite that makes up the Volclay system is over 100 million years old. Sodium bentonite is most widely known for its ability to swell. It can absorb up to five times its weight in water and at full saturation may occupy a volume 12 to 15 times its dry bulk. When bentonite absorbs water it takes on a gel-like consistency which is resistant to fracturing or cracking. When installed correctly, the sodium bentonite will form a watertight barrier for the life time of the structure.

A common misconception is that bentonite is prone to drying out. There are two important aspects to consider in the wet / dry cycle of bentonite. Firstly, bentonite creates a strong suction force that will in most situations prevent it from losing water once it hydrates. Secondly, any water that could theoretically be lost through evaporation will be quickly regained through absorption from a sub-grade or saturated zone in an attempt to achieve equilibrium conditions.

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Volclay Swelltite

Allco Waterproofing Solutions

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Volclay Swelltite is a bentonite waterproofing membrane designed for below grade masonry block, split-slab deck and plaza construction.

Swelltite is designed for waterproofing below-grade vertical and horizontal structural surfaces, as well as, above grade split-slab construction used with plaza areas, parking garages and sports stadiums.

Swelltite is excellent for:

Below-grade masonry block walls
Split-slab Plaza Deck Construction
Cut & Cover Tunnels
Masonry Block Foundation Walls
Concrete Foundation Walls
Earth-covered Structures

Installation:

Ready for use and requires no set-up
Does not require torching or priming
It can be applied in all weather conditions to green concrete
Can be installed in temperatures below freezing

In the opinion of BRANZ, the Volclay Waterproofing System if designed, used, installed and maintained in accordance with the statements and conditions of this Appraisal, will meet the following provisions of the NZBC:

Clause B2 DURABILITY: Performance B2.3.1 [a] not less than 50 years. the Volclay Waterproofing System meet this requirement. See Paragraph 14.1.
Clause E2 EXTERNAL MOISTURE: Performance E2.33. the Volclay Waterproofing System meet this requirement. See Paragraphs 16.1 - 16.3.
Clause F2 HAZARDOUS BUILDING MATERIALS: Performance F2.3.1. the Volclay Waterproofing System meet this requirement and will not present a health hazard to people.

BRANZ Appraisal is of an Alternative Solution in terms of New Zealand Building Code compliance.

BRANZ Appraised

Volclay Voltex DS & DS/SWR

Allco Waterproofing Solutions

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Bentonite-Geotextile waterproofing system with Integrated Polyethylene Liner, used as a damp-proofing or waterproofing membrane below ground to protect basements and other underground structures against water penetration and water vapour transmission from the ground.

The Volclay Waterproofing System has been appraised for use as:

an external waterproof tanking membrane to in-situ concrete, precast concrete and concrete masonry basement constructions subject to hydrostatic pressures of up to 2 bar (20 metres); and,
a damp-proof membrane (DPM) to slab-on-ground and basement constructions; and,
a waterproof membrane to plaza deck roof structures

Clause B2 DURABILITY: Performance B2.3.1 (a) not less than 50 years. The Volclay Waterproofing System meets this requirement. See Paragraph 14.1.
Clause E2 EXTERNAL MOISTURE: Performance E2.3.3. The Volclay Waterproofing System meets this requirement. See Paragraphs 16.1 – 16.3.
Clause F2 HAZARDOUS BUILDING MATERIALS: Performance F2.3.1. The Volclay Waterproofing System meets this requirement and will not present a health hazard to people.

This is an Appraisal of the Volclay Waterproofing System as an Alternative Solution in terms of New Zealand Building Code compliance.

BRANZ Appraised

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