Geosynthetics April/May 2020 - 15

SMOOTH VERSUS TEXTURED
GEOMEMBRANE ELONGATION
Q: According to the U.S. specification, we
must use smooth geomembrane at the base
or the bottom of tailing storage facilities
and textured geomembranes on slopes
with 79 mils (2 mm) HDPE thickness. In
the specification of our country, there is a
standard method called TS EN ISO 527 for
geomembranes break elongation that is
accepted up to 700% no separated, smooth
or textured. We use the 700% limit if we
follow ISO 527. But when we look at the GRI
GM13 standard specific test method and
frequency of smooth and textured HDPE,
there is the ASTM D6693 standard for smooth
geomembrane the parameter of break
elongation is 700% and for textured the
parameter is 100%.

SERVICE LIFE OF GEOMEMBRANE
Q: We have a client asking us the following
question regarding OIT results: "With the
report of the OIT being 30 minutes versus
the GRI GM13 spec of 100 minutes, would
you think the liner is past its service life?"
What would be the best answer? I have
also attached the OIT report/results.
A: The ratio of old to new is one-third;
therefore, you have had a 67% drop in
standard OIT ASTM D3895 in 15 years. This
is not unheard of and should be contrasted
with other properties of the polyethylene.
Specifically, elongation at break, which I
see is still between 700% and 800%. Based
on your elongation results at break, your
geomembrane still has service life. G

My question is, why is there a different
percentage break elongation between
smooth and textured geomembranes? Why
has the current standard been determined
that the break elongation of the textured
geomembrane is less? If you have these
standards and other documents about
this topic, please forward.
A: With most things in life, there are tradeoffs. If you want high friction (i.e., textured
geomembrane), then you will have lower
elongation at break (i.e., texturing causes
notching and irregularities). When GM13 was
written, a compromise was struck to establish
elongation at break of 100%. Please note,
most designs for polyethylene are based
on yield not break properties.

CHEMICAL RESISTANCE
OF HDPE TO CYANIDE
Q: Hope you are doing well. See if you can help
us. An agency in Mexico is worried about 79mil (2-mm) HDPE performance with cyanide (I
guess they are worried about degradation). Do
you happen to have a paper that we can use
to demonstrate and build a case?
A: There are numerous citations of the
chemical resistance of HDPE to cyanide.
Please also note that millions of square
meters of HDPE have been used in gold
mines throughout the world in the
application of heap leach mining.
See attached reference list.

GEOSTAR
Faster. Lighter. Smarter.

GEOSTAR with LQS - Automatic Data Acquisition,
Enhanced QC/QA for Field Streaming, Integrated
Wi-Fi and GPS for easy data transfer
www.leister.com

We know how.

www.GeosyntheticsMagazine.com

0420GS_cv2-15.indd 15

3/23/20 6:20 PM

http://www.leister.com http://www.GeosyntheticsMagazine.com

Geosynthetics April/May 2020

Table of Contents for the Digital Edition of Geosynthetics April/May 2020