Influence of the Degradation on the Stress Cracking Values of High Density Polyethylene (HDPE) Geomembranes After Different Exposures

 

Fernando Luiz Lavoie

Civil Engineering, MSc; Department of Geotechnical Engineering, São Carlos School of Engineering, University of São Paulo (USP), Avenida do Trabalhador Sancarlense 400, 13.566-590, São Carlos (SP), Brazil; e-mail: fllavoie@yahoo.com.br

Benedito de Souza Bueno

Full Professor, PhD; Department of Geotechnical Engineering, São Carlos School of Engineering, University of São Paulo (USP), Avenida do Trabalhador Sancarlense 400, 13.566-590, São Carlos (SP), Brazil; e-mail: bsbueno@sc.usp.br

Paulo César Lodi*

Associate Professor, PhD; Department of Civil Engineering, UNESP – São Paulo State University, Av. Eng. Luiz Edmundo C. Coube 14-01, 17.033-360, Bauru (SP), Brazil; e-mail: plodi@feb.unesp.br

* Corresponding Author

 

 ABSTRACT

This paper presents results from stress cracking (SC) tests performed in both fresh and exposed high density polyethylene (HDPE) geomembranes (GM). The HDPE GMs were exposed to ultraviolet radiation, thermal aging (air oven) and tested for chemical compatibility with sodium hydroxide. Stress cracking tests in both fresh and degraded samples were performed in accordance to ASTM D5397: Notched Constant Tensile Load Test (NCTL) and Single Point-Notched Constant Tensile Load Test (SP-NCTL). The results of the NCTL showed that the geomembrane degradation process can be considered to be a catalyst for the phenomenon of SC because it caused a 50% to 60% reduction in stress crack resistance. The most resistance reduction was observed for the sample under chemical compatibility with sodium hydroxide. For the SP-NCTL, the results showed that the samples maintain the same trend verified in the NCTL. The largest resistance reduction was evidenced in samples undergoing ultraviolet degradation.

Keywords: Stress Cracking, HDPE Geomembranes, Degradation.

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