Geosynthetics August/September 2020 - 44

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GSI NEWS

Lifetime assessments for
B/C ratio evaluations is
an essential process to
all geosynthetic projects.
Definitive answers can
be elusive. However,
armed with decades
of case histories and
experimentation, the
geosynthetic community
is now better equipped
to make estimates on
service life based on
specific geosynthetic
materials performance.

44

are key "tells" that your geosynthetic is
reaching the end of its service life:
*	 Material thickness decrease of 30%
(Stark, Choi and Diebel 2005)
*	 Density increase in excess of 0.04 g/cc
(Haxo 1982; Hsuan and Koerner 1998)
*	 Oxidative induction time (OIT)
decreases to 1/3 of specification (33
standard and 133 min. high pressure)
(Hsuan and Koerner 1998; Koerner
2016; Rowe, Rimal and Sangam 2009)
*	 Stress crack resistance less than 150
hours (Hsuan, Lord and Koerner 1991)
*	 Change in melt flow index of 30%
(Benson and Dwyer 2006)
*	 Tensile elongation at break, decrease
of 50% (Apse 1991)
*	 Initial or break modulus, 30% stiffening (Zanzinger and Martin 2018)
*	 Change (pass versus fail) of impact
resistance (Rollin, Mlynarek and
Zanescu 1994)
Additionally, decreases in geosynthetic performance over time can
also result in observable surface degradation (chalking, flaking or cracking), as well as affect the feasibility of
maintaining or repairing the material
(seaming the material may no longer
be possible after a certain amount of
degradation occurs).
In conclusion, lifetime assessments
for B/C ratio evaluations are part of
an essential process to all geosynthetic
projects. Definitive answers can be elusive. However, armed with decades of
case histories and experimentation, the
geosynthetic community is now better
equipped to make estimates on service life based on specific geosynthetic
materials performance. These newer
estimates are usually adequate for economic predictions such as B/C. Finally,
it is important to note that a material
reaching the end of its service life does
not mean immediate failure of the system due to redundant safety and design

considerations implemented by the
project engineer. However, to ensure
dependability, safety and reliability of
the solution, replacement before end of
life is encouraged.
References
Apse, J. I. (1991). U.S. EPA computer code on Flexible
Membrane Liner Advisory Expert System (FLEX),
Cincinnati, Ohio, EPA Risk Reduction Laboratory.
Benson, C. H., and Dwyer, S. F. (2006). "Material
stability and applications." Chapt. 3 in Barrier systems
for environmental containment and treatment, ed. C. C.
Chien, H. I. Inyong, and L. G. Everett, CRC Press, Boca
Raton, Fla., 143-201.

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Haxo, H. E. (1982). "Effect on liner materials of
long-term exposure in waste environments." Proc.,
8th Annual Research Symposium: Land Disposal of
Hazardous Wastes, EPA-600/9-82-002, U.S. EPA,
Cincinnati, Ohio.

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Hsuan, Y. G., and Koerner, R. M. (1998). "Antioxidant
depletion lifetime in HDPE geomembranes." Jour.,
Geotech and Geoenvironmental Engineering, 124(6),
532-541.

NA

Hsuan, Y. G., Lord, A. E. Jr., and Koerner, R. M. (1991).
"Effect of outdoor exposure on a high density
polyethylene geomembrane." Proc., Geosynthetics
1991, IFAI, St. Paul, Minn., 287-302.

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AD

Koerner, R. M. (2016). "Lifetime predictions of exposed
geotextiles and geomembranes." Proc., GeoAmericas
2016, vol. 1, Miami Beach, Fla., 1-46.

ST

PH

Peggs, I. D. (2004). "Geomembrane liner durability:
Contributing factors and the status quo." Jour.,
Environmental Science, https://doi.org/10.1680/
gpte.32347.0001, Corpus ID:138299534.

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Rollin, A. L., Mlynarek, J., and Zanescu, A. (1994).
"Performance changes in aged in situ HDPE
geomembranes." In Landfilling of Waste: Barriers,
E&FN Sons, ed. T. H. Christensen et al. Chapman Hall,
London, 915-924.

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Rowe, R. K., Rimal, S., and Sangam, H. (2009). "Ageing
of HDPE geomembrane exposed to air, water and
leachate at different temperatures." Jour., Geotextiles
and Geomembranes, 27(2), 137-151.

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CR

Stark, T. D., Choi, H., and Diebel, P. W. (2005).
"Plasticizer retention in PVC geomembranes," Proc.,
GeoFrontiers 2005, ASCE, GSP, 130-142.

AC

Zanzinger, H., and Martin, A. (2018). "Evaluation tests
on PE-HD geosynthetic barriers after exposure tests,"
Proc., 11th ICG, Seoul, Korea. G

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Geosynthetics | August September 2020

0820GS_p38-cv4.indd 44

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Geosynthetics August/September 2020

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