Asphalt Mixture Quality Acceptance using the Hamburg Wheel-Tracking Test

Abstract

This paper investigates the applicability of the Hamburg wheel-tracking test (HWTT) for asphalt mixture quality acceptance using laboratory-compacted specimens and field-compacted specimens. Density distribution functions for rut depths, stripping inflection points, and rutting resistance index (RRI) values used in the HWTT were obtained for mixtures with different nominal maximum aggregate size (NMAS) values and binder performance grades. Clear distinctions among the rut depth distributions for the high-temperature performance grade mixtures were observed in the laboratory-compacted specimens. The RRI values for both the laboratory and field-compacted specimens increased with an increase in the binder performance grade. In addition, the RRI values showed clear differences for different binder grades among the mixtures with the same NMAS. The range of the RRI distributions for the laboratory-compacted specimens was narrower than that of the field-compacted specimens. The stripping inflection points of the field-compacted specimens increased as the binder grade was increased, indicating better moisture damage resistance for stiffer mixtures. HWTT results were significantly influenced by the air voids content of specimens. The relationship between air voids content and RRI can be used for understanding the critical effect of in-place density in pavement performance. The laboratory-compacted and field-compacted specimens offer advantages and disadvantages. The laboratory-compacted specimens were much easier to fabricate to standard dimensions, and the field-compacted specimens present inherent variability in relation to air voids content, diameter, and thickness.