ABSTRACT
Low temperatures decrease the ability of an asphalt mixture to relax after repeated traffic loading and therefore the probability of cracking is increased and becomes even more critical with ageing. In order to prevent cracking appropriate mix design with suitable aggregates and high quality bituminous binders are the prerequisites. Additionally, it is always important to study and understand the performance behaviour, which in this case is related mainly to temperatures below 0°C. For such assessment several test methods are presently available. This research compares two different destructive methods of asphalt testing in low temperature range with focus on flexural strength (three-point bending beam test) and crack propagation test. Three-point bending beam test according to the Czech technical specifications TP151 was performed on un-notched beams. In addition, half of the test specimens was tested after artificial laboratory long-term ageing according to pr EN 12697–52 (5 days at 85°C). The load-deformation diagram was used to calculate the fracture energy. At the same time SCB test according to EN 12697-44 was performed on notched semi-cylindrical test specimens. For some of the tested mixtures the same laboratory long-term ageing protocol was used and aged test specimens were tested again for the same crack propagation test. In both cases ageing index was defined and gained values for particular SMA mixtures compared.
