Plastic Lumber Rail Ties
A new ASTM International standard presents all the requirements needed so that plastic lumber materials can be appropriately specified for uses, such as main and secondary framing members, in which improved mechanical properties are essential. D7568, Specification for Polyethylene-Based Structural-Grade Plastic Lumber for Outdoor Applications, was developed by Subcommittee D20.20 on Plastic Lumber, part of ASTM Committee D20 on Plastics.
D7568 is applicable to solid, rectangular SGPL products in which polyethylene resin (non crosslinked) is the continuous phase and represents at least 50 percent of the product by weight. Fiber reinforcements used in SGPL products include manufactured materials such as fiberglass (chopped or continuous), carbon, aramid and other polymeric materials. The new standard provides criteria under which SGPL products can be produced. It also includes calculation equations for some parameters.
“Plastic lumber materials are alternatives to wood and wood/plastic composite materials, and structural-grade plastic lumber materials can be used in a variety of applications, including decks, bridges and railroad ties,” says Marcelo Hirschler, GBH International, and a longtime member of ASTM International. Plastic lumber is resistant to moisture, rot and insects, and does not need chemical treatments.
Plastic lumber products as covered by D7568 can be used as main framing members, including joists, stringers, beams and columns as well as secondary framing members, which would include planking, posts and bracing. In addition, the specification covers the use of plastic lumber in outdoor structures such as decks, boardwalks, docks and platforms.
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CONTACT Technical Information: Marcelo M. Hirschler, GBH International • Mill Valley, Calif. • Phone: 415-388-8278 | ASTM Staff: Alyson Fick • Phone: 610-832-9710 | Upcoming Meeting: Nov. 10-13 • November Committee Week • Jacksonville, Fla.
This article appears in the issue of Standardization News.