The influence of UV aging of a Styrene/Butadiene/Styrene modified bitumen: Comparison between laboratory and on site aging

During the service life in a pavement, neat bitumen and modified bitumen age as the result of the mixing with aggregates, the process of laying, the climatic conditions and the traffic. Laboratory methods for simulating the short-term and long-term ageing (RTFOT and PAV, respectively) are standardized. None of them takes into account the influence of UV radiations. In the particular case of a pavement located in south France, a comparison is drawn through Fourier Transformed InfraRed (FTIR) analysis. Three types of ageing are compared: the standard simulated ageings, the actual on site ageing after 12 and 26 months of road service and the ageing when UV exposure in a weathering oven follows RTFOT simulation. According to carbonyle function evolution by FTIR spectroscopy, this work shows that for all tested binders, the same ageing level as the one simulated by PAV is reached in a few hours when a thin film of binder is submitted to UV exposure after RTFOT. It is also to be noted that the level of the on site ageing of a SBS Polymer modified Bitumen (PmB) reaches the simulated PAV ageing after 12 months of pavement life.