CAIT project no.: PA RU9247
Fiscal Year: 2005/2006
Rutgers-CAIT Author(s): Thomas Bennert, Ali Maher
Sponsor(s): USDOT, PA NY/NJ
The PANYNJ is moving towards performance-based evaluations of hot mix asphalt (HMA) to verify the cost new and innovative HMA mixes for use on the George Washington Bridge and on airports, such as Newark Liberty International. HMA mixes for the George Washington Bridge were evaluated using repeated load testing, the Asphalt Pavement Analyzer, Flexural Beam Fatigue, and Dynamic Modulus. The various mixes evaluated consisted of Epoxy-based HMA, asphalt-rubber HMA, Rosphalt (which is an asphalt rubber based mix), and a PG76-22 asphalt binder with fibers. Laboratory testing concluded that the Epoxy-based HMA provided excellent rutting and fatigue properties, however, the mix has a tendency “set-up” and cure at sometimes unpredictable times, thereby, not lending itself to traditional paving delays that occur. The Rosphalt mix performed almost as well as the Epoxy-based HMA, but without the “set-up” issues. All “innovative” HMA mixes tested outperformed the current in-place I-5 PG76-22 in both rutting and fatigue testing. Work conducted on the interface bond testing of HMA cores taken from Newark Liberty International Airport showed clearly showed that HMA with a granite-gneiss aggregate had lower repetitions to debonding than HMA with Trap Rock aggregates. The laboratory results were validated by field observations of debonding in areas where granite-gneiss aggregates were used. Testing was conducted used a bi-axial repeated load test to simulate the axial and shear stresses developed during airplane trafficking. Asphalt Pavement Analyzer (APA) testing of different a FAA #3 surface course mix with various PG-graded asphalt binders showed that, as expected, asphalt binders with higher PG grades are less susceptible to rutting. The results indicated that the fuel resistance asphalt binder, high PG graded at 94oC, accumulated half of the total APA rutting as the PG64-22.