By Gordon Anderson, waterproofing consultant at a.b.e. Construction Chemicals
Factory-produced “torch-on” membranes, containing various modifiers, have been the waterproofing system of choice over the last three decades and currently represent over 70% of the local waterproofing market.
However, the South African specification market is now seeing an increase in the use of liquid waterproofing coatings and additives to render concrete mixes waterproof and watertight. Some of these systems, which have been around long enough to build verifiable performance track-records, are fast replacing the traditional torch-on application.
Globally speaking, torch-on systems are declining in Europe, and currently they only represent about 20% of the USA market.
The use of additives in a concrete mix to render the mix waterproof and watertight has proven successful in both below ground and water containment environments.
There are two principal technologies in this field:
– Crystalline-based, such as Chryso SA’s CWA 10 crystalline waterproofing admixtures.
– a.b.e. Construction Chemicals Pore Blocking system, Fuge B, a hydrophobic additive.
Crystalline-treated concrete will react when a crack is exposed to water by forming crystals that, over a period of time, will render the crack leak-free – as long as the crack is static. A dynamic crack though, will need further treatment. Pore blocking, on the other hand, restricts water ingress to the cured concrete.
Polyurethane, Polyurea and hybrids
Polyurethane, Polyurea and hybrid products are also making their presence felt in both the international and local markets.
While polyurethane and hybrid waterproofing systems are easier to apply, either by brush, roller or low-pressure spray, and more forgiving when it comes to substrate strength and surface profiles, it is never equivalent to a Polyurea system. A waterproofing industry expert once aptly described Polyurea as “a polyurethane on steroids to provide an all-round superior performance”.
A well specified, properly applied Polyurea system invariably produces a first-class result, but sometimes a Polyurea specification falls into the waterproofing section of the Bill of Quantities. The problem is that not many traditional waterproofers own the necessary plant and equipment – or indeed the skills – to achieve the desired end-result when applying a relatively complex Polyurea system.
Polyurea systems are applied under high pressure with the heated components being brought together at the nozzle of the spray gun and sprayed to a defined thickness. The curing time can vary from seconds to 12 minutes. Polyurea is generally ultraviolet (UV) resistant, has very good elongation characteristics and, in buried situations, is root-resistant.
Experience and expertise
Waterproofing is a rapidly changing and complex environment, so to avoid confusion and disastrous results it is always wise to consult the experts before specifying or starting any project. Both a.b.e. Construction Chemicals and its holding company, Chryso SA, have the technological experience and expertise to help in this regard.
a.b.e. Construction Chemicals
Tel: 011 306 9000
Caption: Modern waterproofing systems include traditional torch-on membrane coatings as well as the relatively new high-tech Polyurea roof protection.