A large experimental campaign on the characterization of the linear viscoelastic behaviour of different bituminous materials was carried out. The goal was to establish the links between the linear viscoelastic properties (which are observed in the small strain domain) of binders and those of bituminous mixes. The linear viscoelastic behaviour of bituminous binders and mixes was studied by performing complex modulus tests at different temperatures and frequencies. A unique rheological model (called “2S2P1D model”) was developed for the modelling of linear viscoelastic properties of both bituminous binders and mixes. This model consists of a generalization of the Huet-Sayegh analogical model. Analyses on test data for five binders and different mastic and mix composition, show that the introduced model fits quite well the measurements. Finally, from our first results, a transformation that is independent of the introduced model allows the mix complex modulus to be predicted easily and efficiently from the binder complex modulus.

The mechanical behavior of bituminous mixes is very complex. It is also characterized by great thermal sensitivity. In the small strain domain (for strain amplitudes below approximately 10−4), it can be considered to be linear, therefore the linear viscoelasticity theory can be applied. In addition, the time temperature superposition principle (TTSP) may be assumed, with a good approximation. This has been widely verified regarding the unidimensional behavior of bituminous mixes in the viscoelastic linear domain. This paper provides an overview of TTSP for bituminous materials, and three-dimensional (3D) behavior and nonlinear domain are also considered. The 3D behavior is characterized by measurements of the complex modulus and complex Poisson’s ratio. For both parameters, master curves are plotted to check the validity of TTSP in 3D. Some experiments in the nonlinear domain (considering strains up to some percentages and some crack propagation tests) are also conducted in equivalent conditions o...

A new approach is proposed to determine the global response of an orthotropic bridge structure from the behavior of the constituent materials that are binders, aggregates and steel. Experimental results and modeling using constitutive models (2S2P1D and DBN) developed by ENTPE team are presented for the bituminous materials in the linear domain. From these results, a transformation that is independent of the introduced models allows the bituminous mix complex modulus to be predicted from the bitumen complex modulus. Then, the response of a 3D orthotropic steel deck bridge subjected to moving wheel loads is presented using numerical Finite Element Method (FEM). The influence of temperature and viscous behavior of surfacing layers on the structure response such as deflection and longitudinal stress are emphasized.

The present paper deals with the energy dissipation induced by the viscous behavior of bituminous materials constituting pavement. An approach to take into account viscous properties of bituminous layers and to quantify this dissipation is explained. First, the behavior of different bituminous materials is investigated. Linear viscoelastic modeling is then proposed using a rheological model previously developed at the Civil Engineering and Buildings Department (DGCB) of the University of Lyon / ENTPE (Ecole Nationale des Travaux Publics de l’Etat). Second, this model is implemented in a finite-element code, which enables simulation of the behavior of any pavement structures under any rolling load. In this paper, these developments, previously validated for orthotropic steel bridge and mix surfacing structures, are applied on a classical French pavement structure. In addition, the calculation of energy dissipation due to the viscous properties of the bituminous materials is allowed. Then an estimat...

In this study, cyclic tension-compression tests on cylindrical specimens are performed in order to investigate fatigue characteristics of bituminous mixtures. Sinusoidal loading is applied at 10 Hz in controlled axial strain mode at 10°C. Axial strain and axial load are measured as well as radial strain, thanks to a specially designed device. The evolution of Poisson’s ratio and volumetric strain is observed during fatigue tests. Fatigue test results are analyzed considering six different fatigue life criteria (using either classical complex modulus drop, nonhomogeneity of the strain field, or dissipated energy evolution, among others). During the first phase of fatigue tests, some skewing phenomena (e.g., thixotropy and heating) are predominant and create reversible effects that must not be interpreted as fatigue. A method to take into account these phenomena is also applied to obtain a corrected damage value at failure. This parameter is shown to be a constant intrinsic value. Based on this resu...