1. Scope

1. Scope

1.1 This test method presents a technique for determining the strain hardening modulus of HDPE geomembranes, based on ASTM D6693 testing.
1.2 This test method can be used for testing smooth HDPE geomembrane of thickness between 0.5 and 5 millimeters (20 and 200 mils)
1.3 This test method is used to develop a test method from which the susceptibility of unaged HDPE geomembrane sheet material to stress cracking under a constant tensile load condition and an accelerated environmental condition can be predicted using strain hardening modulus value.
1.4 The test method will facilitate comparison of characteristics of similar materials by standardizing the method for deriving the onset, modulus, and break point on the stress-strain curve from an HDPE Dog Bone Tensile Test. Strain hardening data can be appropriate for assessing the stress crack susceptibility of HDPE geomembranes. However, it should be very clearly stated that this method shows a good correlation between strain hardening modulus and stress crack performance within a specific formulation (resin type plus master batch). In addition, this method shows very poor correlation between strain hardening modulus and stress crack performance across different formulations. As such, this method is a useful manufacturing quality control (MQC) tool but is not appropriate for setting specification criteria by engineers to compare different geomembranes. To this end, if formulations are compared, they should be of the same supplier, grade, and density.
1.5 The values stated in SI units are to be regarded as the standard. The values given in imperial units (in parentheses) are for information only.
1.6 This test method does not purport to address all the safety concerns, if any, associated with its use. It is the responsibility of the user of this test method to establish appropriate safety, health, and environmental test methods and


determine the applicability of regulatory limitations prior to use.
1.7 This test method was developed in accordance with
Internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides, and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
1.8 The strain hardening modulus testing procedure specified by this test method differs significantly from the strain hardening modulus testing procedure specified by ISO 18488. Departures include but are not limited to the following.
1.8.1 This test is performed on specimens cut from manufactured geomembranes rather than 0.3 mm compression molded coupons.
1.8.2 This test utilizes cross head movement rather than deflection data from an extensometer for elongation determinations.
1.8.3 Test is conducted at standard laboratory temperature rather than at elevated temperature.

Keywords

14. Keywords 14.1 Strain hardening modulus; high-density polyethylene; stress cracking

Rationale

New Test Method to compliment ASTM D5397 on evaluating HDPE geomembrane stress crack resistance

The title and scope are in draft form and are under development within this ASTM Committee.