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Requirements for PE geopipes in German landfills with regard to stress cracking resistance and oxidation resistance

According to the European Landfill Directive, all components of the sealing system must fulfil their function over a very long period of time. The suitability of geopipes in landfills must be proven and their professional installation within the framework of quality management must be demonstrated. The SKZ/TÜV-LGA quality guideline represents here for the state of the art in Germany. PE geopipes must be made of PE 100 or PE 100-RC materials. PE 100-RC materials have a higher resistance to slow crack growth than PE 100 materials. PE 100-RC are therefore preferably be used in the basic sealing system.

In Germany, a service life of 100 years for continuous temperatures of up to 40°C is the requirement basis for permanent applications of drainage pipes as a function-determining element of the sealing systems in landfills. These characteristic values are determined by testing the long-term hydrostatic strength. Moreover polyolefins are also subject to ageing processes due to oxidation, media influences and temperature. Therefore, proof of the ageing resistance to thermal oxidative degradation and to the leaching of stabilizers must be provided by investigations in liquid media under oxygen pressure and elevated temperature in high-pressure autoclaves. Current research results of PE pipes with high thermo-oxidative resistance for applications at higher temperatures and long service lives prove the fundamental suitability of PE geopipes for this application. The verification method for the suitability of PE geopipes with high thermo-oxidative resistance for applications at higher temperatures and long service lives is presented here.

Within the scope of quality monitoring, tests are carried out on PE moulding compounds, tests on thick-walled and profiled PE geopipes within the framework of factory production control and control tests on the construction site. Accelerated testing methods such as oxidation resistance testing with high-pressure autoclaves and stress crack resistance testing with the strain-hardening method play an important part in this