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1. Plastic Lumber Technology

2. Manufacturing Process
• Making High Density Polyethylene (HDPE) Product
– Material preparation
– Grinding into chips
– Screw extruder
– Melting and Mixing
– Molding (finished product)

3. 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.

4. 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

5. 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

6. 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