Assessment of ZSV in Asphalt Concrete Using Shear Frequency Sweep Testing

This study elaborates on methods for assessing the material property called zero shear-rate viscosity (ZSV) in asphalt concrete based on shear frequency sweep testing. The purpose of ZSV assessment is for linear viscoelastic permanent deformation modeling. The basic approach was to fit parameters of the Laplace-transformed Burger’s model to the measured shear dynamic modulus data. This method produced multiple solutions, although an approximate measure of the minimum ZSV could be estimated. Therefore, extrapolation was necessary to assess the frequency-independent ZSV based on the measured frequency sweep data. The method was complemented with the simplified Cross extrapolation model that was successfully fitted to the measured data. The extended method also produced multiple solutions, although the minimum ZSV could be assessed unambiguously. The results were in accordance with expectations based on measured dynamic shear modulus and phase angle.