Plastic Lumber Technology

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