Cynthia Teniers of EVAL Europe has been studying the use of ethylene-vinyl alcohol copolymers (EVOH) to reduce volatile organic compound (VOC) loss through geosynthetics. Liners are used to protect the environment by containing liquids and vapour emissions; however current monolayer membranes can permit VOCs to pass through. If a 2-4% EVOH layer is added to a PE or PP membrane, or even to the clay liner, it can greatly improve the barrier performance. During production of the multilayer polymer membrane an adhesive tie layer is needed.
H&R ChemPharm has developed a new liquid applied super absorbent polymer system, which forms a film coating and embeds in the substrate. It is currently in use in cables in a coated-yarn layer to protect optical fibres. The company has received enquiries from consultant geo-engineers about using this system in geomembrane applications as it blocks water and contaminants and is self-healing. The Technical University of Munich and Bolton Textile Institute have been studying the potential. The production method is simple – fabric is immersed in a bath of polymer and then pressed through heated rollers above 120C before being rolled up.
Fire performance is a critical requirement of building materials. Warrington Fire Gent carries out fire testing to look at factors like flame spread. The standards which apply to roofing include ENV 1187 (CEN TS 1187) and EN 13501-5. Protocols include placing a basket of wood wool onto the roof construction test sample and flaming for 30 minutes with the roof at different angles. Each European member state chooses a test method and level of safety.
The International Green Roof Association has highlighted the safety features for roofing including wind uplift, structural load bearing capability, fire regulations and drainage. It is particularly important to check the membrane joins and to test for leaks. A finished roof needs fall protection, which can be a rope and harness system for maintenance, or full fencing for a roof with public access. High rise gardens have been opened in Singapore and New York offering a park experience in the centre of the city.
In the late 1950s Fatra produced one of the world’s first PVC geomembranes for use in a dam in Dobsina. This Czech company now produces waterproof membranes for a variety of applications including ground waterproofing for new buildings, which need to act as a radon and moisture barrier. The advantage of synthetic membranes is the speed of installation, low labour, movement with the building minimising tears and cracks, and excellent chemical resistance. However, they are thin compared to bitumen and can be torn during installation. An active check system can be built in to show where leaks are occurring and to facilitate repair. It is much more critical to get ground waterproofing right first time, because of the difficulties of access and the consequences of failure. Leak detection systems are available from Sensor in Bratislava and permit remote monitoring of membrane installations.
The waterproof membrane market is growing worldwide and providing multifunctional components to the construction industry and aiding in the move to LEED certification, by incorporating cooling, gardens and alternative energy functions. The next AMI networking event for the industry, Waterproof Membranes 2011, is scheduled for 15-17 November 2011 at the Maritim Hotel, Cologne, Germany.
Market and technology trends for waterproof membranes