Effect of time–temperature, strain level and cyclic loading on the complex Poisson’s ratio of asphalt mixtures

Abstract

Complex modulus and complex Poisson’s ratio are two parameters which characterise the 3D linear viscoelastic properties of asphalt mixtures. Compared to the complex modulus, the complex Poisson’s ratio is more difficult to be measured because of the great accuracy needed for the experimental device. This investigation focuses on the complex Poisson’s ratio of asphalt mixtures and the effect of loading parameters on its values. The three loading parameters considered in the paper include the time–temperature, the strain level and the number of cyclic loadings. To fulfil the objective of study, complex modulus tests, fatigue tests combined with the rest time, large amplitude cyclic loading tests and cyclic permanent deformation tests are performed. The complex modulus tests are conducted at different temperatures, frequencies and strain amplitudes. Thanks to the fatigue tests, the large amplitude cyclic loading tests and the cyclic permanent deformation tests, the change in complex Poisson’s ratio with the number of cycle, the pre-deformation strain level of specimen and the accumulated permanent deformation (up to some %) respectively is also investigated. The obtained results show that the time–temperature and the number of cyclic loading have a clear effect on the complex Poisson’s ratio of asphalt mixtures. No significant change in the complex Poisson’s ratio is observed when varying the strain cyclic loading amplitude within the small strain domain. The change in the complex Poisson’s ratio becomes more important and is observed to be proportional with the norm of the strain deviator tensor when the axial strain is accumulated or pre-loaded up to some percent.