In the recent years rheology has been taking an increasing importance in the characterization of bituminous materials. Rheological parameters are suggested by many studies as good indicators of the performance of these materials and tools to efficiently predict the performance and durability of asphalt pavements. Bituminous materials exhibit a non-linear mechanical response beyond a certain level of sollicitation. This behaviour is important as it is a source of error in linear stiffness measurements. Fatigue tests on bituminous materials are typically performed in the non-linear region. ln the present study, non-linearity of bituminous binders and mixtures was investigated through strain sweeps and fatigue tests. The development of non-linearity was described and quantified. It was found the strain level effect has the same impact on mechanical properties as the accumulation of cycles. A phenomenological description of this behaviour is proposed, based on the destruction of supra-molecular structures.
