What is the difference between plastic lumber and wood-plastic composites?
• Wood-plastic composites have at least 50% or more wood fiber, while plastic lumber can have less than 50% wood fiber. The standard for determining design values for wood-plastic composites is still being balloted in ASTM by committee D07 and is designated, Standard Test Methods for Evaluating the Mechanical and Physical Properties of Wood-Plastic Composite Products. Its scope states, “1.2 Because this Test Method is under the purview of Committee D7 (Wood), the scope is primarily applicable to WPC materials containing 50% or greater wood content by weight (oven dry basis).” The standard for determining design values for plastic lumber was developed by ASTM Committee D20 and is designated ASTM Test Method D6435-99 “Standard Test Method for Shear Properties of Plastic Lumber and Plastic Lumber Shapes.” Its scope states, “1.1 This test method covers the determination of the mechanical properties of plastic lumber and plastic lumber shapes when loaded in shear at relatively low uniform r
