Evaluation on Stress Cracking Resistances of Various HDPE Drainage Geonets

Specimens from each geonet were placed under various compressive loads in a vessel containing a solution of 10% surface-active agent and 90% water at a temperature of 50°C. Then the surface morphology study of the specimen was performed after 500 hours test duration. The results show that all of these geonets did not appear any kind of stress cracking in the condition of 400 kPa, which is a typical landfill’s loading condition. However, in the case of bi-planar geonet there were some deposits on the surface of geonet’s strand and it is expected that this phenomena is due to the results of chemical clogging. On the other hand, in the case of the tri-planar and circular type bi-planar geonets, it maintained very clean flow channels until the end of the test. For high normal pressure some environmental stress cracks were detected for the circular type bi-planar geonet. The results show that the resistance to the environmental stress cracking is related to its polymer density, crystallinity and also rigidity not its mechanical properties.