On 1 July 2024, the Australian Federal government Environmentally Sustainable Procurement (ESP) Policy came into effect. The policy focusses on goods that contain recycled content and can be recycled at the end of their useful life. Tenderers are encouraged to demonstrate within their bid how they will meet these focus areas sustainably.
For plastic stormwater pipes there are several products available in Australia that incorporate recycled materials and can be recycled at the end of their useful life. 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.
For PE stormwater pipes, one of the most critical failure modes is slow crack growth. 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 recycled materials, additional testing is required that is currently outside the scope of AS/NZS 5065.
In the USA, 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.
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 recycled materials have been successfully installed.