Ravelling by traffic: Performance testing and field validation

The use of new types of asphalt mixtures for thin to very thin surface courses is seen as a cost-effective solution for reducing traffic noise in Belgium. However, ravelling is a major concern for this type of mixtures and there is a need for a standardized laboratory test to predict resistance to ravelling caused by shear forces (also known as “scuffing”). The Belgian Road Research Centre (BRRC) uses the Darmstadt Scuffing Device, an apparatus developed in Germany for testing porous asphalt. This paper describes the experience of BRRC with this test device. As a first step, it was verified whether the test is capable of discriminating between mixtures other than porous asphalt, the mixture type for which the apparatus was originally designed. The second step was to verify if the ranking of mixtures is in agreement with the observations on the road. Therefore, the test was applied to mixtures from different test sections that are being monitored at regular times, a work that will be continued in the coming years. While this work is going on, CEN TC 227 WG1/TG2 is in the process of drafting a European standard for the scuffing test (prCEN/TS 12697-50). The results of this research will be used to contribute to the development of a standard European test method.