A three-year study of corrugated high density polyethylene pipe used for drainage underneath a commuter rail line in Pennsylvania found "no discernible differences" in performance between the pipe made from virgin resin and one made from recycled material.
Pipe experts say the results of the field and lab evaluation mark an important step toward validating the use of pipe manufactured with recycled plastic for railroad applications and most likely highway uses, too.
HDPE pipe with post-consumer materials has been used for decades in agricultural applications but railroad specifications require pipes be made with 100 percent virgin materials. The big concern has been that the service life of the pipe could be compromised by the presence of contaminants in the recycled content.
However, to incorporate more sustainable and cost-effective practices, the transportation industry has expressed interest in using pipes made with recycled content — if the long-term performance is equivalent to pipes made with virgin materials, according to Michael Pluimer, who worked on the study while earning his doctoral degree at Villanova University in Philadelphia.
Villanova conducted the study with the Southeastern Pennsylvania Transit Authority (SEPTA) on HDPE pipe made from 49 percent post-consumer content as part of SEPTA's sustainability initiatives. The university funded the study along with the National Cooperative Highway Research Program (NCHRP).
Starting in October 2013, Pluimer and a team of university engineers monitored the performance of pipe installed underneath the passenger rail line near Doylestown. Then, they evaluated the pipes' service life in terms of fatigue and stress cracking based on an accelerated lab study.