Procedures currently used in the design of mixtures have several major deficiencies that affect the reliability of the designed mix. The results obtained from investigations of mix behavior in the gyratory testing machine (gtm) indicatethat deficiencies in mix design are primarily associated with the characteristics of the aggregates, particularly the gradation. Mixtures compacted in the gtm to simulate field compaction were tested at 60 deg c (140 deg f) in the gtm to simulate traffic densification. It was observed that high-quality aggregate blends (no significant rutting) exhibited low sensitivity to change in asphalt content and maintained high shear resistance except at the highest asphalt content. Gtm tests conducted on mixtures duplicating those observed to have early and excessive pavement rutting exhibited high sensitivity to asphalt content, lower shearresistance, and sensitivity to changes in gradation. The results obtained from this investigation indicated that the gtm can be used to evaluate the effect of aggregate characteristics on hot-mix properties and to develop procedures for mix design. This paper appears in transportation research record no. 1259, Chip seals, friction courses, and asphalt pavement rutting 1990.
Abstract