ELIMINATING STRESS CRACKING (SC) IN HDPE AND PP GEOMEMBRANES – A SURVEY
Eliminating Stress Cracking (SC) in HDPE and PP Geomembranes – A Survey
Ian D. Peggs
I-CORP INTERNATIONAL, Inc.
Can SC be eliminated altogether? Probablynot. But it can still surely be reduced if we understand its causes a little better.
We have made great improvements (specified NCTL times from 200 to 1000 hr) since the 1980s when there were extensive slow crack growth (SCG) and rapid crack propagation (RCP) or “shattering” failures in exposed HDPE geomembranes. However, neither SCG nor RCP have totally gone away.
Recently I have seen SC events that I have never seen before after quite short service periods. For instance, while I have seen many SCs along the peaks of wrinkles I had never seen SCs across wrinkles as shown in Figure 1. It is believed that complex cyclic stresses caused these accelerated breaks after only 2 years in service. Nor had I seen isolated patches of four or five SCs in geomembrane panels with no cracking at adjacent welds, as shown in Figure 2, after only 6 months in service. There has also been an RCP shattering event in Canada this year.
If anyone has seen anything similar to these three SC events some photographs and background information would be welcome.
Figure 1.Transverse SC on wrinkle.
Figure 2.Four isolated stress cracks (adjacent to white lines).
Given sufficient time I hope to submit a paper to the 10th International Geosynthetics Conference in Berlin that will list basic details of SC events that have occurred internationally since the start of 2010 and would ask anyone who knows of a stress cracking event to complete the attached questionnaire and to send it to me. We will identify the predominant causes of SC events and define how they may be prevented. We may come back to you for more detailed information which will be treated as confidential.
QUESTIONNAIRE RE WORLD WIDE STRESS CRACKING EVENTS
IN HDPE AND PP GEOMEMBRANES SINCE START OF 2010
Name:______
Company:______
Email:______
DATA / HDPE / PPMonth/year of failure
Month/year of installation
SCG on seam / Yes No / Yes No
SCG in panel / Yes No / Yes No
RCP/shattering / Yes No / Yes No
Service temperature high / °C °F
Service temperature low / °C °F
Low temperature at failure / °C °F
Rapid temp drop at failure / Yes No / Yes No
Photos/figures attached / Yes No / Yes No
Please complete and return to Ian D. Peggs at by the end of April 2013.
This is a general interest study, not a paid consulting project.
Thank you.