The Single Point-Notched Constant Load Test: A Quality Control Test for Assessing Stress Crack Resistance

The stress crack resistance of some geosynthetics, such as high density polyethylene geomembranes which are made from semi-crystalline polymers, must be properly evaluated to justify their long term performance. The newly adopted ASTM D 5397 notched constant tensile load test can be used to make a proper assessment of stress crack resistance. From the results of a notched constant tensile load test, a minimum time to reach the beginning of the brittle portion of the response curve can be established. Unfortunately, the test takes too long to generate the required data (on the order of weeks or months) for it to be considered as a quality control or conformance test. This paper presents a single point version of the notched constant tensile load test, called the single point-notched constant tensile load test. If the appropriate stress level, testing temperature and incubation medium are selected a much shorter testing time of approximately 24 hours can be achieved. Thus, the test can be used as a quality control, or conformance test.