Implementation of Ultra-Thin Whitetopping in Florida

In 1996, the Florida Department of Transportation (FDOT) started a research project to evaluate design, construction and performance of the ultra-thin whitetopping on asphalt pavements. Three UTW test tracks were constructed at the FDOT research facility in Gainesville, Florida. The design of the UTW test tracks included thicknesses ranging from 50 to 100 mm, and joint spacings ranging from 0.92 m to 1.83 m. The UTW was constructed on 40 mm thick asphalt surface. Tests were performed to evaluate concrete strength properties and shearing strength at the concrete-asphalt interface. The test tracks were subjected to approximately 60,000 (80 kN) ESALs using a truck loaded with large concrete blocks. Falling Weight Deflectometer (FWD) tests were performed frequently during the 18-month loading period. Test results showed excellent bond between concrete overlay and asphalt surface. The FWD tests indicated significant improvement in the load carrying capacity of the composite pavement. Success of this research prompted the FDOT to implement the first UTW on a truck weigh station on Interstate 10 (I-JO) in northwest Florida. The objective was to place an UTW on an existing asphalt pavement which had suffered from severe rutting and cracking problems. Two UTW sections were designed using 80 mm and 100 mm respectively. Within each section two joint spacings were used, 1.2 m and 1.6 m. High strength concrete was designed for both sections. Polypropylene fibers were included in the concrete mixture for one section of the project. This paper discusses the research project, and implementation of the UTW including design, specification, construction and performance of the UTW on 1-10 weigh station in Florida.