A description is presented of ongoing research by the Florida Department of Transportation on feasibility studies to use recycled plastic wastes for fence line posts and guardrail posts as mandated by a 1988 state law. All test work focused on acquisition of data for selected essential properties and characteristics, including durability; resistance to insects, soil microorganisms, and environmental exposure; water absorption; and flexural and tensile strength. Initial studies entailed property measurements of high-density polyethylene sheeting (milk bottles) used in A-frame bamcades. Low strain rate tests produced failure at a strain of approximately 1.0 for flawed material but did not fail for flawfree material at a strain of 2.6. Large-diameter posts showed major variations in composition and properties. Exposure tests showed warpage on posts with small cross sections. Flexure to failure whole post tests indicated that some posts were stronger than concrete and were possible candidates for guardrail posts. Resistance tests for soil microorganisms showed no effect. Boiling water and boiling saline had no effect on dimensional changes on most post discs. A11 discs absorbed liquid after 8 to 10 hr of exposure. Insect exposure tests (fire ants and termites) indicate that posts containing cellulosic material may not be suitable in termite-infested areas due to high weight loss. A fence post specification framework is proposed. Other components currently under testing and evaluation are listed.

It has been estimated that the construction, rehabilitation, and maintenance of the nation’s highways annually requires 350 million tons of construction materials (natural and manufactured). This includes 20 million tons of asphalt, 10 million tons of portland cement, and 320 million tons of natural aggregates, paving mixtures, coatings, and so forth (I). Many state agencies have developed or are developing and implementing procedures to include a variety of waste materials in construction and rehabilitation processes. This is in response to increasing environmental concerns about solid waste disposal, environmental hazards, and location of new disposal sites.