Sealing is indispensable for environmental and groundwater protection and contributes substantially to the fitness for use and service life of buildings. Geomembranes of varying thickness, depending on the intended purpose, are used as barriers to liquids and gases mainly in landfills and tunnel construction and in hydraulic engineering. Typically,geomembranes manufactured of various polyethylene formulations (e.g.different densities) are used. Thicknesses are generally more than 1.0mm. Geomembranes are deployed and welded together by approved installers. In areas with reduced stresses, plastic sheets with thicknesses of 0.3 mm to 1.0 mm can be used. This would be applicable for non-permanent covers and, for example, pond applications. Geosynthetic clay liners are used in specific areas, with bentonite performing the sealing function.
In landfills HDPE geomembranes (thickness higher or equal 2.0 mm) are used nearly exclusively. In groundwater protection, mainly 1.0 mm thick HDPE geomembranes are used. In tunneling applications, mostly geomembranes with a signal layer are installed. Steeper slopes can be accommodated by installing a geomembrane with structured surfaces. Needle-punched geosynthetic clay liners with mechanically bonded nonwovens (300 g/m2) as cover and carrier geotextiles are especially suitable for steeper slopes because they normally achievehigher interface friction angles than other geotextiles.