Intrinsic resistance to non-reversible deformation in modified asphalt binders and its relation with specification criteria

The research reported herein deals with the use of different rheometrical approaches to evaluate the damage-related properties of modified asphalt binders at high service temperatures. Starting from the basic assumption that binders damage behavior at high temperatures can be described by separating delayed elastic phenomena from viscous deformation mechanism, static and repetitive creep experiments were performed to associate specific characteristics of the binders’ time-dependent response to the materials damage resistance in conditions of incipient failure. In any case, the viscous component of the creep compliance calculated by linear modeling was found to be the most important factor which controls and predicts the binder resistance to the propagation of viscous flow. Nevertheless, the analysis of binder response in creep experiments shown that several inconsistencies with theoretical fundaments arise when modified binders with high delayed elasticity are considered. In these cases, the ratio of the material retardation time to the experiment time scale does not allow the achievement of a steady-state and a correct description of the mechanical response cannot be easily achieved. The influence of rheometrical aspects on the reliability of the measurements was consequently studied in order to attain a reduction of the necessary approximation. The concept of intrinsic resistance to non-reversible deformation was then proposed to outline performance-based criteria for technical qualification of modified asphalt binders.