Development of a tribological test for asphalt
Résumé
The measurement framework allowing for analyses on standard products, such as dense hot-mix asphalt, must be completed to analyse the behaviour of porous cold-mix asphalts. Such soft materials need time to stabilise its performances and short-term loading can drive to large deterioration of the applied layer. The effects of wheel tread turning and rubbing on asphalt surface have to be understood. In order to do that, the tribological behaviour of an asphalt surface is studied using an apparatus that can load a sample surface simultaneously in compression and torsion. The paper describes the technical details and the design of the apparatus, followed by a description of the adopted experimental test protocol. Tests are realised with imposed normal load and rotation rate of a disc. The adhesion and friction stresses are calculated from torque measurement. The displacement of sample surface during torsion is recorded. The value of this parameter at the end of the test appears as a useful degradation indicator. Performing tests during ageing of sample enlighten us on the stabilisation of the performances. The interpretation of results is illustrated by tests carried out on porous cold-mix asphalt that is particularly sensitive.