Effect of Test Temperature on Hamburg Wheel-Tracking Device Testing

Abstract

This study outlines statistical analyses carried out to investigate the effect of test temperature on results from Hamburg wheel-tracking device (HWTD) tests. The Hamburg test database and aggregate properties database of the Texas Department of Transportation (TxDOT) were examined and merged to provide the basis for statistical analysis. Because the most significant effect of test temperature was on the binder component of the asphalt mixture, the effect of test temperature on the binder type was also investigated. Finally, the influence of test temperatures together with the combined interaction of binder and additive addition is studied. Of the three performance-graded (PG) binders that TxDOT predominantly uses for their surface mixes, this study determined that the influence of temperature on binder performance is most pronounced in PG 64-22 (causing a huge drop in success rate between 40 and 50°C from an 81% pass rate to a 35% rate), whereas PG 76-22 was the most resistant to temperature difference. Test temperature and average deformation were also found to have a positive correlation, and mixes with higher PG binder developed less deformation than low-grade mixes. Finally, this study concluded that in comparing antistripping agent additives, lime performed better than liquid antistripping additives, and liquid antistripping additives performed better than no antistripping agents in HWTD tests. This indicates that lime is the best additive type for stripping (deformation) resistance. It has a pass rate of 81.5%. The next best type is liquid with a 61.2% pass rate.