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3 CHAPTER 1 Introduction The corrugated drainage pipe market in the United States 3. Identify whether contaminants present in recycled HDPE consumes in excess of a billion pounds of virgin high-density will adversely affect the long-term service life of finished pipe; polyethylene (HDPE) annually. At the same time, millions of 4. To the extent possible, evaluate the performance of existing pounds of recyclable HDPE are generated each year. Industry- installations of corrugated drainage pipe produced from funded research has demonstrated the feasibility of blending blends of virgin and recycled HDPE; and recycled and virgin HDPE to manufacture corrugated drainage 5. If warranted, develop specifications and test methods to pipe. The working hypothesis is that good quality pipe can be support the use of recycled HDPE in the manufacture of manufactured from such blends if critical material properties corrugated drainage pipe. that affect pipe performance and durability, such as strength and structural properties, density, melt index, environmental The objectives of this study were to stress-crack resistance, and thermal stability are consistently maintained at specified levels in the blends. 1. Determine the availability, properties, and consistency of At present, AASHTO specifications do not permit the use recycled HDPE intended for use in the manufacture of of recycled HDPE in the production of corrugated drainage corrugated drainage pipe; pipe. Research was needed to 2. Prepare blends of recycled HDPE with virgin corrugated pipe resins and determine the properties of the blends; 1. Determine if there are blends of virgin and recycled HDPE 3. Select candidate resin formulations containing recycled that meet the current material property requirements spec- HDPE and manufacture 12-in.-diameter, dual wall, cor- ified by AASHTO and defined in ASTM D3350; rugated pipe from the blends; 2. Perform post-production tests on pipe manufactured with 4. Determine the short- and long-term properties of the blends blends of virgin and recycled HDPE to assure its long-term and evaluate if the currently used design standards can be stress-crack resistance and antioxidant effectiveness are used for recycled-containing pipe; and equivalent to that of pipe made from virgin HDPE, as cur- 5. Prepare specifications and standard test methods for resins rently specified in AASHTO M294 or M252; and pipe that contain recycled HDPE.