Rheological, spectroscopic and microscopic assessment of asphalt binder ageing

Abstract

Asphalt binder ageing leads to significant changes in mechanical and physicochemical properties and often to premature cracking in asphalt pavements. A polymer-modified asphalt binder is repeatedly aged through laboratory techniques, i.e. rolling thin film oven test and pressure ageing vessel. The resulting properties of the aged binder are analysed using dynamic shear rheometer, Fourier transform infrared spectroscopy, atomic force microscopy and cryo-environmental scanning electron microscopy. Rheological, spectroscopic and macroscopic properties change progressively with the level of laboratory ageing. Surprisingly, this change shows approximately a linear trend. The first ageing step has the highest impact on the property change, whereas all the following ageing steps result in similar but reduced impact. Moreover, there is a strong interdependency between different mechanical and physicochemical properties. Hence, novel insights into the mechanics of asphalt binder ageing and into the search for ageing laws for asphalt binders.