Relationship between low-temperature KIc and KIIc values of bitumen with different performance grades and comparison with naturally solid materials

Abstract

As a visco-elastic material, asphalt binder acts as a brittle material under sub-zero temperature. The brittleness of this material at low-temperature conditions may result in sudden failure of asphalt pavements by passing the traffic loads. Utilizing the edge notched short bend beam (ENSBB) specimen, critical modes I and II stress intensity factors (KIc and KIIc values) of three bitumen materials (with performance grades 76–16, 64–22 and 82–28) are determined experimentally in this research at two low temperature (-12 and −24 °C) conditions. It was shown that KIIc is noticeably less than KIc for the whole fractured asphalt binders and testing temperatures. The ratio of fracture resistance (KIIc/KIc) that varies from 0.45 and 0.65 for the tested binder materials was estimated using minimum strain energy density, maximum hoop stress and maximum hoop strain failure theories. The low temperature fracture behavior of tested binders (including ratio of KIIc/KIc and cracking path) was in agreement with the behavior of natural solid materials such as Perspex, marble rock and gypsum.