Error message

Deprecated function: The each() function is deprecated. This message will be suppressed on further calls in menu_set_active_trail() (line 2405 of /home/geomec5/public_html/rail/includes/

NCHRP Project 4-39 Field Performance of Corrugated Pipe Manufactured with Recycled Content

Lead Sponsor: 
National Cooperative Highway Research Program
Project PI: 
Michael Pluimer (Leslie McCarthy, co-PI)
Lead Institution: 
Project Description: 
Corrugated high-density polyethylene (HDPE) pipes are an attractive product for culvert and drainage applications in the railroad industry due to their resistance to corrosion and abrasion, long service life, and flexibility. Railroad specifications currently require these pipes to be manufactured with 100% virgin materials. However, corrugated HDPE pipes manufactured with a blend of recycled and virgin materials have been used successfully for decades in the agricultural and private land drainage industries. Incorporating recycled content into corrugated HDPE pipe offers both economic and environmental benefits. From an economic standpoint, recycled materials can cost up to 20 percent less than virgin materials. While the lower cost can be partially offset by reduced manufacturing efficiencies, there still can be an economic benefit to using these materials. There are also significant environmental advantages in the production of the pipe, as the production of the virgin raw materials is one of the largest contributors to the overall environmental impact of the pipe system when performing a cradle to grave analysis. Substituting recycled polyethylene for virgin materials in the raw material stream used to manufacture the pipe will reduce the environmental impact associated with production, as the refining process inherent in the production of virgin raw materials will be minimized. For these reasons, the railroad industry would benefit from using corrugated HDPE pipes manufactured with recycled content. The primary concern with using corrugated HDPE pipes manufactured with recycled materials for railroad applications is the durability with regards to repeated live loads. Specifically, there are concerns that contaminants in the material stream could act as stress risers that could cause fatigue-related cracking over time. To evaluate the performance of corrugated HDPE pipes made with recycled content in rail applications, a pilot study was conducted with the Southeastern Pennsylvania Transit Authority (SEPTA). The study was funded cooperatively by SEPTA and the National Cooperative Highway Research Program (NCHRP) Project 4-39. Two 30-inch diameter corrugated HDPE pipes, one manufactured with 100% virgin materials and one manufactured with post-consumer recycled content, were installed underneath a regional commuter rail line in northeast Philadelphia with 2 feet of cover from the top of the pipe to the bottom of the railroad tie. The pipes were instrumented with strain gages and extensometers to record live-load data and monitor the pipes over time. A laboratory study was also developed to assess the long-term durability of pipes made with recycled content with regards to cyclical live loads. The pipes have been in service for over 1.5 years and are performing as designed, with no change in performance since the date of installation. Additionally, test specimens with various blends of recycled and virgin materials have been tested in the laboratory to over 2 million cycles. The research indicates that fatigue-related failures do not appear to be a concern for properly installed corrugated HDPE pipes manufactured with recycled content, and the service life of these pipes with regards to fatigue cracking should exceed 50 years.