Three Dimensional, Axi-Symmetric Geomembrane Tension Test

Presented in this paper are details of a three dimensional, axi-symmetric, tension test used to determine the stress-vs-strain behavior of geomembranes. From this data the modulus, strength and elongation can be obtained. After evaluating the effect of load rate, the accuracy of the test was illustrated by a series of 10 tests on VLDPE geomembranes. This test series resulted in a standard deviation of approximately ± 10%. A variety of different HDPE geomembranes were evaluated with only nominal differences resulting from different manufacturing processes. Lastly, a variety of different geomembrane types were tested and compared to one another. All of these test results show a marked contrast to the usually performed one dimensional tension tests and result in substantially different behavioral trends. The test details and procedures are presented along with the theory that is required to convert the pressure-vs-deflection readings into stress-vs-strain values. The test is recommended for the type of out-of-plane loading conditions that occur at the bottom of reservoirs and landfills, and for liners used for covers over subsiding landfills and other compressible subgrade materials.