Prediction of bituminous mixes fatigue behavior during laboratory fatigue tests
Résumé
Fatigue performances of bituminous material are evaluated using laboratory fatigue tests. Classical interpretation is based on the specimen fatigue life for a given damage criterion. The loading amplitude effect is given by the Wöhlen curve but it does not integrate the damage rate along the material history. A continuum damage mechanics approach is proposed here to describe the material loss of stiffness under cyclic loading. The local Young moduluss loss is modelled introducing a scalar damage variable. The damage law can be fitted using the uniaxial tension compression fatigue response. For a given material and fixed testing conditions, agreement between experimental data and computed values is obtained for tension compression, bending. In a second step the model is applied on two bituminous mixes leading to very much different fatigue behaviour in laboratory to test the model relevance. Effect of the binder nature is expressed through the damage evolution parameter values.