Effect of PG binder grade and source on performance of superpave mixtures under Hamburg Wheel

Rutting and stripping of hot-mix asphalt pavements continue to be major problems even after the Superpave mixture design has been implemented. In this study, the effects of Performance Grade (PG) binder and source on the Superpave mixtures used on a project on US-169 in Kansas have been studied with the Hamburg wheel tester. The objective of the study was to assess whether the PG binder grade (and its source) used on this project had any impact on the premature rutting observed. The effect of compaction of the Superpave mix before wheel testing was also investigated. The test results were statistically analyzed using the Analysis of Variance (ANOVA) technique. The PG 70-28 binder grade appeared to perform better than all other PG binders used in the study. The Superpave mixtures showed significant difference in performance in terms of the numbers of repetitions to reach maximum 20 mm rut depth and to show stripping when compared by the binder source. Mixture compacted with lower air voids performed much better than the mixtures compacted with only two percent higher air voids. This implies that better compaction is a prerequisite for better performance of the Superpave pavements. Key words: binder hot-mix asphalt pavementwheel testin