Asphalt mixes deformation sensitivity to change in rheological parameters

An algorithm for determining the rheological parameters of asphalt mixes in the creep test in the Nottingham Asphalt Tester (NAT) is presented. It was found that the smallest errors in identification of the rheological parameters are made for the third cycle of loading. The determined rheological parameters were verified by testing the mixes in the French Pavement Rutting Tester (FPRT), for which a rutting test model based on the finite-element method (FEM) was developed. Also the deformability of the asphalt mixes tested in the FPRT is analyzed. It is found that the viscosity coefficient eta(1), and the delayed elasticity coefficient E-2 have a significant effect on rut depth in the rutting tester model. An analysis of the deformation sensitivity of the viscoelastic courses in a pavement structure model shows that the binder course's rheological parameters, especially the viscosity coefficient eta(1), contribute most to rutting in the pavement. The deformation of this course is determined by the duration of the load. The deformation of the wearing course is influenced by the delayed elasticity modulus E-2, and it depends mainly on the time between cycles of loading.