For plastic stormwater pipes there are several products available in Australia that incorporate varying levels of PCR.  These are typically manufactured from polyethylene (PE) as this material is currently the most readily available waste stream.  The challenge for these products has been to not only meet a relevant Australian product standard but to also demonstrate a long service life without premature failure.

For PE stormwater pipes, one of the most critical failure modes is slow crack growth.  The Australian Standard for PE and polypropylene (PP) stormwater pipes, AS/NZS 5065 “Polyethylene and polypropylene pipes and fittings for drainage and sewerage applications”, includes test requirements for slow crack growth for pipes manufactured from virgin material.  For PE pipes that include PCR, additional testing is required that is currently outside the scope of AS/NZS 5065.

In the US, the un-notched, constant ligament stress (UCLS) test has been developed and embedded in ASTM standards to assess the slow crack growth of various blends of recycled and virgin PE materials.  The UCLS test is now included in PIPA POP208 “Specification and testing guidelines for recycled materials suitable for non-pressure plastic pipe applications. Polyethylene, Polypropylene and Rigid PVC” with a view to eventually being incorporated into Standards such as AS/NZS 5065.

There are clearly incentives for tenderers to include recycled PE stormwater pipe in their project.  It is equally important, however, that the checks and balances are in place to ensure that any installed product will have a long, failure-free service life equivalent or greater than that of product manufactured from virgin material.

This paper will examine UCLS test results from various PE stormwater pipes available in the Australian market that contain PCR.  It will also include a case study of a major road project where PE stormwater pipes containing recyclate have been installed.