Photodegradation of hot-mix asphalt

Photodegradation of asphalts must be considered in the study of the performance of asphalt pavement, especially in geographical regions where a high solar radiation intensity occurs. The aim of this work is to study asphalt ageing caused by the effect of xenon radiation, by using environmental tests. The spectral profile of a xenon arc is very similar to the solar radiation spectrum. Hot-mix asphalt samples were submitted to a weathering test, with cycles of exposure to a xenon radiation and humidity, and the sample degradation was evaluated using thermal analysis, Fourier transform infrared spectroscopy, and gel permeation chromatography. After the weathering test, the thermal stability of asphalt binder decreased. The qualitative analysis by using gel permeation chromatography indicated a decrease of the molecular weight of the asphalt binder after the weathering test. The results of the Fourier transform infrared spectroscopy analysis indicate an oxidation process of material, which occurred during the weathering test. The normalized absorbance of the peak associated to the CO group and OH group increased in relation to the total area of peaks for the hot-mix asphalt samples, after exposure to xenon radiation.