Waterproof membranes are used in a wide range of civil and building applications. Around 750,000 tonnes of polymer will be used in building membranes in Europe in 2008 according to Jon Nash, Strategic Research Manager at Applied Market Information. He was speaking at an industry forum, 3-5 November 2008: Waterproof Membranes 2008, in Cologne, Germany. The primary material used in membranes worldwide is polymer-modified bitumen. Polyethylene accounts for around 50% of the rest of the market, followed by polypropylene, PVC, and EPDM and butyl rubber. Romania, Poland and Slovenia are showing the highest rates of construction industry growth in 2008, whereas Western European markets are declining.
In Russia the construction market is growing rapidly, however it can be a difficult business arena with issues like economic corruption. NTC “Gidrol –Krovlja” quotes membrane production in 2005 at 545 million square meters, rising to 625 in 2007. This is sufficient to meet local demand and around 75 million square meters was exported in 2007 with low levels of imports. 97.5% of the membranes are bitumen-based, compared to 70% in the European Community. TechnoNICOL is the largest producer. PVC comprises 72% of the small polymeric membranes market.
Water Seal Company LLC is based in the United Arab Emirates. Roof in the region receives considerably less rainfall and the membrane is expected to last for the life of the building. Basement waterproofing is more important because the water table is very high. Until recently, the market share was primarily modified-bitumen with around 5% EPDM, and 10% other systems (PVC and liquid waterproofing). HDPE is now making inroads. The overall trend is towards Green Roofing Systems.
Wolfram Sparber of EURAC described the use of roofing for solar power generation – the aim is to create zero energy buildings. Flexible photovoltaic cells have been made with a PTFE/glass fabric backing. These have been incorporated into roofing membranes in projects with UniSolar, Geovest, Solar Integrated and Yuma Solar. These solar roofs are produced by companies such as Solar Integrated, which uses membrane from Sika and integrates photovoltaics from United Solar Ovonic. It is a very lightweight system.
Optigruen provides expertise in living, green (growing) roof systems. These assist with sealing and insulation, reducing the effects of extreme temperatures. A root proofing system is required and drainage is a very important consideration. The Tokyo Institute of Technology is evaluating root resistance of joints in membranes. Solvent welding was more resistant than using double-coated adhesive sheet. A simple test is proposed of needle penetration.
Grace Construction Products has looked at basement waterproofing. Groundwater can be high in chemicals, particularly in the Gulf, and contamination enters buildings by the wick effect and diffusion. Solutions include bentonite clays on a HDPE carrier; PVC sheets with welded waterstop sections; adhesive and pressure sensitive adhesive (PSA) membranes, such as Bituthene; pre-applied adhesive membranes such as Preprufe with a tough film combined with a PSA and a protective coating.
Davis-Standard is a leading supplier of production equipment including extrusion coating and laminating machinery for reinforced membranes. Dow is heavily involved in the membrane market and has developed polyolefins for different applications including Inspire PP, Versify PBE and Engage POE for roofing and geomembranes; Elite EPE and Dowlex LLDPE for pitched roofs and geomembranes; Nordel EPDM for single-ply and reservoir liners; and Tyrin CPE for single-ply.
GSE Lining Technology has examined the lifetime of HDPE membranes: the primary factors are UV ageing, thermal ageing and environmental stress cracking. Buried membranes are predicted to last for 260 years (GRI), or 300 years (BAM). UV exposure is being tested at sites in Germany, Spain and Iran: the additive package, material quality and thickness are all critical and the oxidative induction time (OIT) is proving a useful test for ageing. AGRU Kunststofftechnik has extensive experience in membranes for tunnel sealing – the geomembrane is laid over the inner concrete in combination with a geotextile. BAM has been testing these VLDPE membranes and predicts a 127 year lifetime.
The Center for Environmental Innovation in Roofing has looked at the environmental impact of membranes: EPDM, TPO and PVC are very similar in global warming potential. The service life is a big factor in the calculation. EPDM membranes retain physical properties at around 25 years in both exposed and covered applications, with a predicted service life of 50 years.
Flag has described the earliest use of membranes in pond linings in the 1960s. The preparation of the subsurface is critical, often requiring a geotextile. One Flag project was the Dubai International Airport; another was the Metropolitana Milanese which used 20 million square meters. Deltares has worked on typical Dutch tanking constructions, which are crossings below the water level such as roads and canals, requiring geomembrane waterproofing. The biggest problem is detecting and repairing leaks. The Institute of Geotechnical Engineering has examined membranes and lining structures for reservoirs: texturing adds significantly to strength.
Performance is critical in roofing. BRE Global is working on fire test methods to match the European Construction Products Directive (CPD), which aims to harmonise standards across member states. There are four test procedures involving burning brands, wind, and supplementary radiant heat. Chemtura supplies REACH approved stabilisation packages into the PVC membrane markets. Ciba has UV stabilisers for PVC and TPO membranes.
Waterproof membranes have a vital role in a range of environmental applications from water conservation, to greening of the cities, insulation and reduction of storm water runoff with roof gardens, to active energy production with built in solar cells. An international forum is held in November each year in Cologne by Applied Market Information to debate these developments.