Comparison of PVC and HDPE Geomembranes

Product Specification

PVC and HDPE are generally preferred for most of the geomembranes applications but each type of geomembrane material has different characteristics which affect installation procedures, lifespan and performances. PVC and HDPE have different mechanical and physical properties, as well as, field applicability. However, depending on specific application, both have been widely used in many applications. Some of the major differences between the two materials are:

  • PVC geomembranes are flexible and relatively easy to handle, while HDPE geomembranes are tough and non-flexible. In cold weather conditions the handling of HDPE geomembranes is a big handicap.
  • HDPE geomembranes tend to exhibit a sharp peak in their stress-strain curve and therefore, tend to undergo a relatively abrupt failure whereas PVC undergoes a very large amount of elongation before failure.
  • It is universally recognized that the field seaming is potentially the most problematic aspect for liner construction. Due to its flexibility, it is possible to do a majority of the PVC seams under controlled factory-conditions because they can be folded easily. HDPE geomembranes, however, still need to be seamed in the field. A PVC liner may require as low as 20 percent the field seams required by a HDPE liner.
  • PVC is very difficult to puncture than a rigid geomembrane because PVC has a high elongation characteristic. Flexibility is the most desirable property of a PVC geomembrane, offering no re-alignment of the molecular chains when elongated. It conforms easily to sites, and in most applications does not require reinforcement.
  • Much of PVC's deformation (up to the break strain) is recoverable. In HDPE strain in excess of about 12% (the yield point) is not recoverable. HDPE is also elastic, but only through elongation up to it’s yield point, at about 12%. Then the material becomes plastic. When the yield point is exceeded, HDPE is no longer the same material. It is no longer elastic and changes to a plastic state. Once the HDPE material has elongated beyond the 12% yield point, it can no longer function as a geomembrane. Since PVC is an amorphous material, it does not have a yield failure point like crystalline materials. PVC is an elastic material. It remains elastic throughout its elongation all the way up to the break point. Therefore, the failure elongation for PVC is the break point, which is 380% for 30 mil PVC. Engineers can safely design using strain limits two or three times higher by using PVC geomembrane
  • PVC has excellent ductility. PVC conforms to sub-grade better than HDPE.
  • HDPE has higher apparent strength but PVC conforms better and maintains an impermeable barrier.
  • 30 mil smooth PVC geomembrane is functionally equivalent to 60 mil textured HDPE geomembrane.
  • Textured polyethylene liners were originally developed in order to compete with the slope stability characteristics of smooth PVC, much the same as Low Density Polyethylene (LDPE) liners were developed to compete with the flexibility characteristics of PVC. Smooth PVC geomembranes are inherently able to provide much higher residual friction angles and to provide stability with soils and other geosynthetics on much steeper slopes than smooth HDPE, and in many cases, textured HDPE.
  • Since PVC geomembrane is an amorphous material, it is not subject to environmental stress cracking. Nor does PVC geomembrane stress crack when exposed to multi-axial stresses.

Polyethylene geomembranes are crystalline plastic and are subject to environmental stress cracking. The higher the density of the resin, the more likely the sheet is to stress crack.

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