ASTM D6109 – Flexural Properties of Plastic Lumber

Standard: ASTM D6109 Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastic Lumber and Related Products

Scope: Per ASTM D6109: "These test methods are suitable for determining the flexural properties for any solid or hollow manufactured plastic lumber product of square, rectangular, round, or other geometric cross section that shows viscoelastic behavior. The test specimens are whole 'as manufactured' pieces without any altering or machining of surfaces beyond cutting to length. As such, this is a test method for evaluating the properties of plastic lumber as a product and not a material property test method. Flexural strength cannot be determined for those products that do not break or that do not fail in the extreme outer fiber."

Products: Plastic lumber, wood-plastic composite (WPC) deck boards

Procedure: Per ASTM D6109: "A specimen of rectangular cross section is tested in flexure as a beam either in a flat, or 'plank,' mode (Method A) or edgewise, or 'joist,' mode (Method B) as follows: The beam rests on two supports and is loaded at two points (by means of two loading noses), each an equal distance from the adjacent support point. The distance between the loading noses (that is, the load span) is one-third of the support span…The specimen is deflected until rupture occurs in the outer fibers or until a maximum outer fiber strain of 3 % is reached, whichever occurs first."

Result: Test results such as flexural strength and stiffness may be reported.