XR-5 Geomembrane during installation
over EPS Geofoam on Ohio’s Interstate 75.
Seaman Corporation Photo
Permeability for geomembranes is actually measured in the laboratory as vapor (water) or solvent transmission rather than a flow of water, which is the measurement used for materials such as clay. The most common test method is ASTM International’s Active Standard D814 (ASTM D814). Some plastics have very low measurable vapor transmission, but those values are theoretical laboratory measurements. Whether the value is measured at 10-9 or 10-12 cm/sec, it is essentially zero. As a reference, compacted clay is on the order of 10-6.
But to achieve such a low vapor transmission rate, the material cannot have holes. It must be constructable. With geomembranes, puncture is a common concern, and puncture resistance is laboratory measured according to ASTM D4833.
This test uses a probe that continuously adds load until a breech occurs. Puncture strength, a good indicator of geomembrane survivability, increases with added weight of the reinforcing fabric and/or polymer thickness. Field workability, on the other hand, decreases with polymer thickness and/or stiffness of the membrane. These are critical considerations, as very low permeability is only effective if the geomembrane can be constructed properly and operated in a secure manner to prevent punctures.
Geomembrane field puncture test samples on light table.
Top photo: Room light on Bottom Photo: Room light off
Seaman Corporation Photos