Construction World October 2016

PRODUCTS AND SERVICES

WATERPROOFING new era in SA By Gordon Anderson, Waterproofing Consultant at a.b.e. Construction Chemicals.

For the past 30 years, the South African and European waterproofing markets have been dominated by factory- produced ‘Torch-on’ membranes, containing various modifiers. The usage of Torch-on membranes currently represents over of 70% of the local waterproofing market.

12 minutes. Polyurea is generally UV-re- sistant, has very good elongation charac- teristics and, in buried situations, is root resistant. Not all Polyureas are the same, however, and in this regard a.b.e. is fortunate to have Polyurea systems developed by the globally-respected German producer, VIP, at its disposal for local distribution. Polyurethane and hybrid waterproofing systems can usually be applied by brush, roller or low-pressure spray and are easier to apply and have more forgiving requirements when it comes to substrate strength and surface profiles but the end-result is never equivalent to a Polyurea system. That, briefly, sums up the waterproofing options available in South Africa today. But 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. Construc- tion Chemicals – which has been involved in waterproofing for over 80 years – and its holding company, Chryso SA, have the tech- nological experience and expertise to help in this regard. Modern waterproofing systems today offers both the traditional torch-on membrane coatings as well as the relatively new high- tech Polyurea roof and deck protection.

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However, in Europe, Torch-on systems are now declining in the USA, while Torch-on membranes have substantially lost ground to

ments where hybrid products are being formulated for possible use in the water- proofing industry but, for now, let us focus on Polyurea and polyurethane. A well specified, properly applied Poly- urea system invariably produces a first-class result but sometimes a Polyurea specification falls into the waterproofing section of the Bill of Quantities. The problem now is that not many traditional, long-established waterproofers own the necessary plant and equipment – or indeed the technical and mechanical skills – to achieve the desired end-result when applying a relatively complex Polyurea system. For this, application is made under high pressure with the heated components being brought together at the nozzle of the spray gun and sprayed to a defined thickness. Curing time can vary from seconds to

T.P.O. (thermoplastic polyolefin) membranes which now claims around 40% market share, followed by E.P.D.M. (ethylene propylene diene terpolymer) membranes. Torch-on membranes, in fact, represent only about 20% of the USA market. The South African specification market also seems to be changing with an increase in the use of additives to the concrete mixes and liquid waterproofing coatings. Some of these systems, which have been around long enough to have verifiable performance track records, are fast replacing the traditional Torch-on application. 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 areas of technology and products in this field: crystalline-based such as Chryso SA’s CWA 10 crystalline water- proofing admixtures, or the a.b.e. Construc- tion Chemicals Pore Blocking system, Fuge B, a hydrophobic additive applied during the concrete mix stage to block pores in the concrete to prevent water passage. There are benefits to be had from the correct application and in the appropriate situation with both these products – but it is important to fully understand the effects of the two systems before specifying or using these products. Crystalline-treated concrete will react when a crack occurs and is exposed to water by forming crystals in the crack and so, over a period of time, it will render the crack leak-free – as long as the crack is static. A dynamic crack would require further treatment. Pore blocking, as stated, restricts water ingress to the cured concrete among other advantages. Then there are also Polyurethane, Poly- urea and hybrid products making their pres- ence felt in both the international and local markets. So what is the difference between polyurethane and Polyurea? A waterproofing industry expert once aptly described Polyurea as ‘a polyurethane on steroids to provide an all-round superior performance’. There are ongoing industry develop-

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CONSTRUCTION WORLD OCTOBER 2016