Effect of binder type, aggregate, and mixture composition on fracture energy of hot-mix asphalt in cold climates

Detrimental effects of low-temperature cracking of asphalt pavements and overlays have motivated new work in fracture testing of hot-mix asphalt (HMA). Recent work has indicated that the fracture behavior of asphalt concrete at low temperatures can be accurately predicted with a testing and modeling system that, along with viscoelastic bulk material properties, relies simply on fracture energy and material strength. In this study, the disk-shaped compact tension test is used to measure fracture energy of 28 HMA mixtures designed for cold climates. Four parameters are investigated: aggregate type (limestone and granite), temperature (three temperatures, encompassing the Superpave® performance graded binder low temperature grade for each binder tested), asphalt content (Superpave design asphalt content and Superpave design content plus 0.5%), and air voids (4% and 7% ). A statistical analysis of results demonstrates the significance for fracture energy of binder content at higher temperatures, aggregate type, and temperature. The air void levels selected and binder content at lower temperatures, however, did not lead to a significant difference in fracture energy. An extrapolation technique is presented that was found to present a rational means for interpreting data from tests that were not finished because of equipment constraints.