Type and Manufacture of Surface Textures

An internal and a gas-infused external layer of geomembrane material or two gas-infused external layers on both sides of the internal layer are co-extruded through a multi-slot co-extrusion die. On emerging from the die, the gas bubbles in the hot material burst on and just beneath the sirrface of the gas-infused external layers and a coarse surface, covered with small craters, develops. This is the so called coextrusion method. 

With the textures applied in a second process step, the base geomembrane of the textured product has identical properties to a smooth geomembrane. However, the above mentioned questions arise of how effective the adhesion of the texture particles is and of their speeific long-term behaviour, i.e. the question of the long-term shear strength of the textured surfaces (Sect. 3.2.18). The problem of stress crack resistance must also be 

Texture manufactured by the co-extrusion process (Process 3) is quite uniform and it offers good friction values in combination with fine grained mineral materials. The texture is evenly distributed over the surface, but their friction resistance cannot be varied or at least only to a small extent. The problem of stress eraek resistance must be considered as with the other textures. Sinee the geomembranes are usually textured throughout the whole surfaee, two textured areas must be welded for each hot wedge weld seam. For the individual co-extruded textures as well as for impinged or laminated textures proof must be provided showing that this is possible without any loss of quality in the properties of the weld seams (Sect. 10.3). 

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