Fracture Energy Method for Determining Stiffness in Polymer Modified Asphalt Binders Using the Single Edge Notched Beam

Transverse cracking is a prevalent problem that occurs in asphalt pavement binders in cold climates and diminishes the integrity of the road as well as shortens the life span of the road leading to premature failure. Current specification for testing asphalt pavement binders for transverse cracking fails to accurately model the behavior of modified asphalt binders because it does not take into account the effects of physical hardening. Furthermore, current specification, which employs the use of the bending beam rheometer (BBR) and direct tension tests, was developed through the use of unmodified asphalt pavement binders and so it does not accurately model the behavior of modified asphalt pavement binders at colder temperatures. This study sought to come up with a new specification criterion for testing for transverse cracking as well as modeling the behavior of modified asphalt pavement binders at colder temperatures. This was achieved by the fracture energy method through the use of a single edge notched beam (SENB). The results showed that the fracture energy method proved to be an effective tool for modeling the behavior of modified asphalt pavement binders. However, when comparing the stiffness calculated from the SENB with that of the BBR we found that the stiffness in the SENB was much higher than that of the BBR. The increase in stiffness could very well be attributed to the differences in the way the samples are tested. Further research is necessary to come up with a way to compare the stiffness calculated from the SENB with that of the BBR before the fracture energy method can replace the BBR method