The objective of this paper is to investigate the relationships among the measured density of an asphalt mixture in the mix design, during quality control (QC) of the mixture (laboratory compaction of a field-produced mix), after initial compaction (after construction and before traffic), after densification by traffic (ultimate density), and after recompaction. Of primary concern is the relationship among density after traffic, mix-design density, and density of laboratory-compacted samples during construction. Eighteen different pavements from six states were sampled. Thirteen were rutting prematurely; five were performing satisfactorily. Construction history, including mix-design data, QC or quality assurance data or both, traffic data, and laboratory data of the physical properties of the pavement cores were analysed from each site. The results show that in-place air-void contents below 3% greatly increase the probability of premature rutting and that the in-place unit weights of the pavements after traffic usually exceed the mix-design unit weight, resulting in low air voids and hence premature rutting.
Abstract