Long-Term Performance of Superpave in Specific Pavement Study 9A

As part of the Long-Term Pavement Performance Program, an experiment identified as Specific Pavement Study 9A (SPS-9A) was established to evaluate the long-term performance of the Superpave® mix design methodology. At each project location, three main test sections were constructed, incorporating the conventional agency mix design, the Superpave Level I mix design with a 98% reliability performance-grade (PG) asphalt binder, and Superpave with an alternative PG binder to evaluate rutting or thermal cracking performance. Further supplementary test sections were constructed at most projects to evaluate the use of other PG asphalt binders with the Superpave mix design. This paper provides a performance comparison and paired T-test analysis of the Superpave Level I mix methodology with conventional agency mix methodology based on the SPS-9A experiment test sections. In addition, the performance impact of PG asphalt binder grades and the use of reclaimed asphalt pavement in Superpave was assessed by statistical analysis of field distresses. Field distresses evaluated in the study include fatigue cracking, thermal cracking, and rutting. Although some trends were identified, overall there was no statistically significant difference in performance between the considered PG asphalt binder grades and mix design types. These results would indicate that asphalt binder and mixture properties probably play a larger role in performance than binder and mix design classification. However, because of the level of asphalt binder and mixture property data in DataPave Release 20.0, a more detailed evaluation of binder and mixture properties on performance was not possible.