Ultraviolet Radiation Ageing of Asphalt: A Critical Review

Ageing of asphalt is an inherent characteristic of the asphalt. During mixing, transportation, and compaction, asphalt undergoes short-term ageing, while during service life it is subjected to long-term ageing. Ageing of asphalt is simulated in the laboratory as thermo-oxidative ageing using a rolling thin film oven (RTFO) and pressurized ageing vessel (PAV). However, during service life, asphalt is subjected to UV radiations and oxygen, due to which, it gets oxidized. This ageing is referred to as photo-oxidative ageing and is not reversible. India is subjected to severe UV radiations throughout the year, but there are no test methods available to assess the UV-ageing susceptibility of binders. In this article, a critical review has been carried out on the UV ageing of asphalt considering various factors including test methods, sample preparation, ageing mechanism, and influence of anti-ageing additives. The review concludes by providing a sound scope for future research and a brief introduction of the work being carried out by the authors in the domain of UV ageing of asphalt.