The role of temperature and binder type on the fracture resistance of asphalt mixtures at low temperatures

In the past decade fracture mechanics concepts have been introduced to the study of the fracture behavior of asphalt mixtures. One of the main goals was to obtain reliable fracture properties that could be used in the selection of crack resistant material and in the development of performance models. This paper presents the results of an investigation of the low temperature properties of asphalt mixtures using a testing protocol and analyses based on the semi circular bend test. The load, the load-line displacement, and the crack mouth opening displacement were recorded during the test and used to calculate the stiffness, the fracture toughness, and fracture energy of three asphalt mixtures used in three test sections at MnROAD facility. The statistical analysis of the experimental data shows that both the fracture toughness and fracture energy are significantly affected by the type of asphalt binder used and the testing temperature. For all three mixtures the fracture energy decreased as the temperature dropped However, the fracture toughness evolution showed a maximum value at approximately the PG low temperature limit of the binder.