3D creep behaviour of asphalt mixtures: Experiment and modelling from complex modulus tests

Abstract

The linear viscoelastic properties of asphalt mixtures can be characterised by the complex modulus or the creep compliance. This paper focused on the creep behaviour of asphalt mixtures and the relationship between the creep behaviour and the complex modulus of asphalt mixtures. 3D complex modulus tests, in which the complex modulus E* and complex Poisson’s ratio ν* were measured, were performed on three asphalt mixtures at six temperatures and five frequencies. The creep tests including loading at fixed constant stress of 0.5 MPa and recovery periods were carried out at three temperatures 15 °C, 30 °C and 60 °C. In addition to the axial strain, the radial strain was also measured in the creep test. The 2S2P1D model was used to simulate the E* and ν* of tested asphalt mixtures and then to calibrate the 3D generalized Kelvin–Voigt model. The evolution of axial and radial strain in the creep – recovery tests were modelled using the creep compliance function obtained from 3D generalized Kelvin–Voigt model. The results showed that the E* and ν* curves generated by 2S2P1D and GKV models fit well with the experimental ones. The transformation from 2S2P1D to generalized Kelvin–Voigt model respected the time–temperature superposition principle. The simulation of 3D creep tests can be established from generalized Kelvin–Voigt model and gives the similar results to experimental data for both loading and recovery period. The evolution of axial and radial strain in the creep – recovery tests respects the time–temperature superposition principle and can be modelled from the E* and ν* of tested asphalt mixtures.