Viscoelastic Modeling of Straight Run and Modified Binders Using the Matching Function Approach

Two models are proposed to describe the rheological behavior of straight run and modified binders in the linear viscoelastic region. These models characterize the absolute value of the complex shear modulus (| G *|) and the phase angle ( i ). They allow for the establishment of master curves based on measurements made at a limited number of loading times and temperatures. A matching function approach was used to develop the models, which were validated experimentally by characterizing the dynamic mechanical properties of polymer-modified and straight run binders at intermediate and high service temperatures. There was good agreement between the measured and predicted values for the complex shear modulus. The phase angle model describes unmodified binders with less than 5% error. Although the model does not simulate the plateau region observed for polymer-modified binders, the error in this case was less than 10%. The models were successfully used to estimate other viscoelastic functions such as the storage and loss shear moduli, and the relaxation spectrum.