Effect of Coarse Aggregate Angularity on Rutting Performance of HMA

摘要

Permanent deformation (rutting) is one of the major distresses in hot-mix asphalt (HMA) pavements. Coarse aggregate angularity (CAA) has an important effect on the rutting characteristics of HMA. More angular coarse aggregates can increase the stone-on-stone interlocking and consequently reduce the rut-susceptibility of mixtures. However, the current specification of CAA is not based on systematic laboratory experiments. The present study related the CAA to the laboratory rutting performance of a dense-graded surface wearing mixture. Mixtures with different levels of crushed gravel were evaluated through the Asphalt Pavement Analyzer (APA) for their rut-resistance. Coarse aggregate properties were characterized through fractured surface counts, direct shear, and resilient modulus tests. Two types of asphalt binder (PG64-22 and PG76-22) were selected for the mixtures. The results from this study indicated that CAA has significant effects on the rutting performance of HMA when the binder grade is critical to the environment. The effect of CAA of less angular coarse aggregate on the rutting performance of HMA was closely related to the depth of the mixtures.