Brice Delaporte

Linear viscoelastic behaviour of bituminous materials: From binders to mixes

ABSTRACT 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.

Linear Viscoelastic Properties of Bituminous Materials Including New Products Made with Ultrafine Particles

ABSTRACT An experimental campaign has been performed at the ENTPE laboratory in order to measure the linear viscoelastic properties (shear complex modulus G*) of mastics with a specifically developed device (annular shear rheometer). Different fillers have been used to design mastics, among which a new type of filler only composed of ultrafine particles. The use of these ultrafine particles induces a significant increase in the complex modulus of mastics at high temperature in comparison to mastics with classical fillers. The potential for reinforcement of fillers is quantified by the complex reinforcement coefficient RM* introduced in this paper. The ultrafine particles have also been used in bituminous mixtures. As it is observed for mastics, an important increase of the modulus is observed at high temperature for the mixtures made with ultrafine filler. Finally, simulations of the linear viscoelastic behaviour of bituminous materials with 2S2P1D model developed at the ENTPE are proposed. Simulations fit quite well experimental results.

Effect of Ultrafine Particles on Linear Viscoelastic Properties of Mastics and Asphalt Concretes

A new type of filler, composed of only ultrafine particles (silica fumes), has been used to design mastics and asphalt concretes. An experimental campaign on mastics and mixtures, performed at the ENTPE/DGCB laboratory, compares the effect of the ultrafine particles to that of “classical” fillers. The linear viscoelastic properties (shear complex modulus G*) of mastics have been measured with a specifically developed device (annular shear rheometer) presented in this paper. The potential for reinforcement of fillers is quantified by the complex reinforcement coefficient RM* introduced in this paper. The results show that the use of the ultrafine particles greatly increases the complex modulus of mastics at high temperature, in comparison to mastics made with classical fillers. In the low-temperature region, the complex modulus is little affected by the filler characteristics. The effect of ultrafine particles has also been analyzed for asphalt concretes, which have been tested using a tension compression test on cylindrical specimens, in the small-strain domain. The analysis reveals that the complex modulus E* is higher for the materials containing ultrafine particles at high temperature, as observed for mastics.

A thermo-viscoplastic model for bituminous materials

This paper introduces the 3D formalism of the DBN (Di Benedetto, Neifar) model developed at ENTPE (Ecole Nationale de Travaux Publics de l’Etat). This model is an attempt to describe with a unique formalism the different types of behavior observed for bituminous materials. The DBN model is very versatile. The proposed formulation can be simplified or adapted following the required property to be introduced. The law can then be very simple and easy to use (linear viscoelastic or even elastic) or more complicated (introduction of non linearity, permanent deformation or fatigue). Considering the thermo-sensitivity of bituminous materials, the temperature influence is always considered.