Performance Factors That Influence Geomembrane Materials

Polymeric Geomembranes

The large number of commercially available geomembranes (or polymeric geosynthetic barriers) can make it challenging to select which geomembrane has the most appropriate combination of performance properties for a given application.  Each type of geomembrane material has different characteristics that affect its installation procedures, durability, lifespan and overall performance. It is therefore necessary to match the project performance criteria with the right combination of properties of a particular geomembrane.

Geomembrane materials are generally selected for their overall performance in key areas of chemical resistance, mechanical properties (elastic modulus, yield strength, puncture/ tear resistance), weathering resistance, product life expectancy, installation factors and cost effectiveness.  The properties of polymeric geomembranes are determined mainly by their polymer structure (architecture of the chains), molecular weight (i.e. the length of the chains) and the crystallinity (packing density of the chains).  Polymer crystallinity is one of the important properties of all polymers.  Polymers exist both in crystalline and amorphous forms.

Common geomembranes can be classified into two broad categories depending on whether they are thermoplastics (i.e. can be remelted) or thermoset (i.e. crosslinked or cured and hence cannot be remelted without degradation) (see Table).  Since thermoset geomembranes are crosslinked, they can exhibit excellent long-term durability.

When selecting a geomembrane for a particular application, the following aspects need to be considered:

Main plastic classifications for common geomembrane types

Thermoplastic Geomembranes Thermoset Geomembranes

Combinations of thermoplastic and thermoset

HDPE, LLDPE CSPE (crosslinks over time) PE-EPDM
fPP EPDM rubber PVC-nitrile rubber
PVC Nitrile rubber EPDM/TPE (Trelleborg)
EIA Butyl rubber Polymer-modified bitumen
TPU, PVDF Polychloroprene (Neoprene)
  • choice of polymer
  • type of fabric reinforcement
  • color of upper ply (e.g. white to maintain lower temperatures for sun exposed applications)
  • thickness
  • texture (e.g. smooth or textured for improved friction angles)
  • product life expectancy
  • mechanical properties
  • chemical resistance
  • ease of installation
Source: Guide To Polymeric Membranes
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