Structural and rheological characterization of wax modified bitumens

The research focuses on the use of waxes as asphalt modifiers. Bitumen/wax blends were produced by addition of controlled quantities of different type of wax to a 70/110 unmodified bitumen. Five different waxes were used, including synthetic hydrocarbons Fischer–Tropsch wax, Montan waxes and amidic-modified waxes. Blends were subjected to different rheometric and thermal testing to relate their characteristics with those of the wax in temperature ranges of technical interest. It was found that bitumen/wax blends have a peculiar and quite complex mechanical response, connected with the melting/crystallizing properties of the wax and the degree of residual crystallinity into the blend. The effects of wax on the binder rheology were found to be mainly controlled by the compositional characteristics of the wax. The experimental program carried out provides different indications for the development of the warm mix asphalt technology and for the general evaluation of wax modification of asphalt binders.