Ten-Year Performance Evaluation of Asphalt-Rubber Surface Mixes

Abstract

In 1988, the Florida legislature passed a bill directing the Florida Department of Transportation (FDOT) to investigate the feasibility and potential use of ground tire rubber (GTR) in asphalt-concrete mixtures. To address this legislative mandate, the FDOT planned and constructed three test projects to define performance that would allow for rational decisions about the use of GTR in Florida. A major finding of a 10-year performance evaluation of these test sites is that the wet process addition of rubber improved the crack resistance of surface mixtures. State Road 16 test sections with wet process rubberized mixes showed about 1 to 6 percent cracked areas, depending on the amount of rubber, whereas those with virgin asphalt or dry-mixed asphalt rubber showed about 30 percent cracked areas. In addition, the cracking data collected during this evaluation appear to suggest that an effective optimum rubber content is within the 10 to 15 percent range. The long-term performance evaluation program of the three test projects is described here and its findings are discussed.