Development of simple relationship between asphalt binder and mastic based on rheological tests

The relationship between the different phases of asphalt materials, from asphalt binder to mastic and mixture, has received significant interest over the years. The Shift-Homothety-Shift in time-Shift (SHStS) transformation developed by the research team of the École Nationale des Travaux Publics de l’État has been found to provide a very effective tool to relate the rheological properties of binders to those of the corresponding mixtures. In this paper, the possibility of using the SHStS transformation to link the behaviour of asphalt binder to that of mastic is investigated with the objective of proposing a simple expression of the SHStS transformation parameter, α, as function of the filler content in the mastic. First, an experimental campaign consisting of dynamic shear rheometer tests is conducted on a set of binders and mastics to obtain the material response at different temperatures and frequencies. Then, the rheological 2S2P1D (2 springs, 2 parabolic elements, 1 dashpot) model is used to evaluate the experimental measurements. Finally, a simple relationship associating the characteristic times of asphalt binder and mastic as function of the filler content is developed. The proposed expression allows to easily and efficiently predict the complex modulus of mastics from the binder complex modulus and vice versa.