Estimation of the SHStS transformation parameter based on volumetric composition

The Shift-Homothety-Shift in time-Shift (SHStS) transformation, derived from the 2S2P1D model, represents one of the most convenient and simple solution for describing the rheological behavior of asphalt materials, when the transformation parameter α is known. In this paper, a simple expression for predicting the SHStS transformation parameter α is proposed. First a set of binders and eighteen different mix designs are used together with the Hirsch model and the 2S2P1D model to derive a regression equation linking α to the binder content and to the fractal dimension of the aggregate gradation. Then, a second set of binders and mixtures is used to experimentally verify the prediction of the α parameter obtained with the newly proposed formulation. It is found that the values of the transformation parameter are in relatively close agreement.