Rheological characterization of wax-modified asphalt binders at high service temperatures

Abstract

The research reported herein focuses on the rheological characterization of wax-modified asphalt binders used in warm mix asphalt (WMA) technology. Wax-modified asphalt binders were produced by adding controlled quantities of different types of wax to a 50/70 unmodified bitumen. Five different kinds of wax were used, including synthetic hydrocarbons Fischer–Tropsch wax, Montan waxes and amidic-modified waxes. All the blends were subjected to different rheometric tests to assess their mechanical response at high service temperatures. The viscous deformation mechanism was analyzed with reference to static and repetitive creep loading; it was found that the viscous deformation is strongly affected by the presence of both hydrocarbons and amidic-modified waxes. Wax-modified binders exhibited an effective improvement in intrinsic resistance to non-reversible deformation, even in high applied stress and cyclic loading conditions. It was observed that the chemical composition and the consequent physical characteristics of the wax are the most important factors regulating the final behavior of wax-modified asphalt binders at high service temperatures. The final contribution of the experience performed is related to the technical evaluation of wax-modified asphalt binders and to the general development of WMA technologies for pavement applications.