Geoysynthetics August/September 2023 - 40

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By George R. Koerner
Need for substitute surfactant
for ASTM D5397
t has been brought to our attention by the ASTM task group regarding ASTM
D5397, Standard Test Method for Evaluation of Stress Crack Resistance of Polyolefin
Geomembranes Using Notched Constant Tensile Load Test, that the surfactant used in
this experiment (Igepal CO-630) is a regulated substance in some countries (i.e., EU
Registration, Evaluation, Authorisation and Restriction of Chemicals [REACH] directive).
For this reason, many labs throughout the world are requesting a substitute-alternative surfactant
for determining the stress crack resistance of High Density Polyethylene (HDPE).
Our industry continues to search for an alternative surfactant for ASTM D5397 that is
effective and available globally.
Improved stress cracking resistance in HDPE geomembranes has been a quest of our
industry for many years, and our industry has made great strides in improving the stress
crack resistance of HDPE geomembranes. The Geosynthetic Institute's (GSI) GRI-GM13
standard specification for HDPE geomembranes has improved the ASTM D5397 (appendix)
single-point notch constant tension load results as follows:
May 15, 2003: Increased minimum acceptable stress crack resistance time from 200
hours to 300 hours.
November 14, 2014: Increased minimum acceptable stress crack resistance time from
George R. Koerner, Ph.D.,
P.E., CQA, is the director of
the Geosynthetic Institute
in Folsom, Pa.
300 to 500 hours.
Much work has been put into the effort to improve stress crack resistance, and we
need to build upon it and not lose ground regarding this important durability property
of HDPE geomembranes. With this in mind, a group of alternative surfactants were used
for this investigation. The group included four surfactants indicated below, which were
chosen based on efficacy and availability.
* Solvay: IGEPAL CO-630 (10% by volume) at 50°C
* Solvay: Rhodasurf LA-9 (10% by volume) at 50°C
* DOW: Tergitol 15-S-15 (5 % by mass) at 70°C
* BASF: Dehyton PL (10% by volume) at 70°C
In addition, we implemented a group of five geomembranes for this investigation into
the round-robin test program. The geomembranes were chosen based on their association
with the Geosynthetic Accreditation Institute-Laboratory Accreditation Program (GAILAP)
proficiency test program. Each had a known stress crack resistance that was developed
by multiple accredited international laboratories for the single-point notch constant
tensile load test (SP-NCTL) appendix " A " of ASTM D5397.
In total, we conducted three sets of round-robin tests in 10 different laboratories. The
results of the round-robin tests are presented in Table 1.
In summary, the results look poor outside of Igepal CO-630. As Table 1 demonstrates,
there is little consistency beyond Igepal CO-630. During the testing, we discovered that
Tergitol at 70°C is a bit of a challenge to work with. At room temperature, Tergitol is a solid

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Geoysynthetics August/September 2023

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