Performance of Corrugated Pipe Manufactured with Recycled Polyethylene Content

The corrugated drainage pipe market in the United States consumes in excess of a billion pounds of virgin high-density polyethylene (HDPE) annually. At the same time, millions of pounds of recyclable HDPE are generated each year. Industry-funded research has demonstrated the feasibility of blending recycled and virgin HDPE to manufacture corrugated drainage pipe. The working hypothesis is that good quality pipe can be manufactured from such blends if critical material properties that affect pipe performance and durability, such as strength and structural properties, density, melt index, environmental stress-crack resistance, and thermal stability, are consistently maintained at specified levels in the blends. At present, AASHTO specifications do not permit the use of recycled HDPE in the production of corrugated drainage pipe. Research is needed to (1) determine if there are blends of virgin and recycled HDPE that meet the current material property requirements specified by AASHTO and defined in ASTM D3350; (2) perform postproduction tests on pipe manufactured with blends of virgin and recycled HDPE to assure its long-term stress-crack resistance and antioxidant effectiveness are equivalent to that of pipe made from virgin HDPE, as currently specified in AASHTO M294 or M252; (3) identify whether contaminants such as polyolefins and hydrocarbons present in recycled HDPE will adversely affect the long-term service life of finished pipe; (4) to the extent possible, evaluate the performance of existing installations of corrugated drainage pipe produced from blends of virgin and recycled HDPE; and (5) if warranted, develop specifications and test methods to support the use of recycled HDPE in the manufacture of corrugated drainage pipe. The objective of this study is to develop specifications and test methods for (1) recycled high-density polyethylene intended for use in the manufacture of corrugated drainage pipe and (2) corrugated pipe manufactured from blends of virgin and recycled high-density polyethylene. In accomplishing this objective, the research will examine the structural and service capabilities of corrugated drainage pipe manufactured with recycled high-density polyethylene in typical transportation applications, and evaluate the applicability of existing design and performance standards for corrugated drainage pipe manufactured with virgin high-density polyethylene to that containing recycled high-density polyethylene.