Low temperature characterization of bituminous binders with a new cyclic shear cooling (CSC) failure test

Low temperature cracking of asphalt pavements is associated to the thermal stresses created when asphalt binder changes from a ductile into a brittle state during cooling. Under repetitive traffic loads, this change of properties can become a significant problem, resulting in the formations of large cracks on the driving surface, thus requiring early pavement repair. Nevertheless, the conventional test methods for assessing low temperature properties of bitumen are often insufficient and subject to low reproducibility. Therefore, a reliable method is necessary to characterize the performance of bituminous binders at low temperature. This work presents the cyclic shear cooling failure test (CSC-failure test) as an alternative method based on a failure test with the dynamic shear rheometer (DSR) at decreasing temperature until fracture occurs. Operational parameters, like shear strain amplitude or loading frequency, have been analysed in order to develop a reproducible procedure applicable for different types of bituminous binders. Moreover, a failure criterion has been defined by analysing the different characteristic temperatures from the failure curves obtained in the test.