Abstract
The Florida Department of Transportation utilizes an open-graded friction course (OGFC), called FC-5, on all multi-lane roadways with a design speed of 50 mph or greater, except for curb and gutter sections, to enhance safety by minimizing hydroplaning. However, FC-5 layers on high-speed multi-lane suburban roadways experience premature raveling owing to high lateral stresses caused by turning, rapid acceleration, and braking activities. Currently, the FC-5 mixture is designed with a 12.5 mm nominal maximum aggregate size (NMAS) gradation and a polymer-modified PG 76-22 binder. To improve the durability of the FC-5 mixtures, alternative OGFC designs using 9.5 mm NMAS gradation and High Polymer-modified (HP) Binder were evaluated. The experimental plan included eight OGFC mixtures designed with three variations: (1) using granite and limestone aggregate sources, (2) using 12.5 mm and 9.5 mm NMAS gradations, and (3) with PG 76-22 and HP binders. The laboratory tests included the Cantabro test, Permeability test, Drainability test, Circular Track Meter test, Dynamic Friction Test, Overlay Test (OT), and Hamburg Wheel Tracking Test, which characterized the mixture’s durability, permeability, drainability, texture, friction, cracking resistance, and rutting resistance, respectively. Note that Cantabro and OT specimens were tested before and after conditioning at Accelerated Weathering System to evaluate the aging resistance of OGFC mixtures. The test results showed that using the 9.5 mm NMAS gradation and HP binder significantly improved the durability, cracking, and aging resistance of the FC-5 mixture without compromising the permeability, drainability, rutting, and friction resistance.
Keywords
Get full access to this article
View all access options for this article.