Plastic Lumber Technologyby Cristian Esparza

Material Science 3344-001

Dr. Larry Peel

September 24, 2008

Manufacturing Process• Making High Density Polyethylene (HDPE) Product

–Material preparation

– Grinding into chips

– Screw extruder

–Melting and Mixing

–Molding (finished product)

Application: Railroad Ties

• More durable than wood

• More cost effective in long term

• 15 million wood ties replaced yearly

• Textured for greater friction

• Comparable in weight to wooden ties.

Application: Plastic Bridge

• Fort Leonard Wood, Missouri (1998)

• First plastic bridge to support vehicle traffic

• 13,000 lb of recycled plastic

• Span of 25 ft

• Supports load of 100 lb/ft2

• Cost of $31,000

• Replaced wooden bridge

Physical Characteristics

• Less stiffness and less strength than wood under winter and summer conditions

• Becomes brittle at low temperatures

• Becomes soft at high temperatures

• Less axial strength than natural lumber under compression, flexure, and tension

• Holds conventional wood fasteners well

• Comparable weight to wood

• Density is between 0.64 and 0.68 g/cc

References

Carroll, D., Stone, R., Sirignano, A., Saindon, R., Gose, S., & Friedman, M. (2003, August). Structural Properties of Recycled HDPE Plastic Lumber Decking Planks. International Journal of Polymeric Materials, 52(8), 709-724. Retrieved August 26, 2008, from Academic Search Complete database.

Composite Railroad Ties Run Wood into the Ground. (1998, April). Civil Engineering (08857024), Retrieved August 26, 2008, from Academic Search Complete database.

Griswold, M. (2007, June 25). Advances in Lumber Hampered by Cost. Plastics News, pp.9.Retrieved August 26, 2008, from Lexis-Nexis Academic database.

Plastics Hit the Deck at Army Base. (1998, October). Civil Engineering (08857024), Retrieved August 27, 2008, from Academic Search Complete database.

Recycled Plastic Lumber. (2008, March 24). Retrieved August 26, 2008, from California Integrated Waste Management Board Web site: http://www.ciwmb.ca.gov/Plastic/Recycled/Lumber/RandD.htm

Trimbath, K. (2006, August). Lumber Made of Recycled Plastic Prevents Marine Borer Damage. Civil Engineering (08857024), 76(8), 28-28. Retrieved August 27, 2008, from Academic Search Complete database.