Evaluating the combined effect of photooxidation and thermal ageing of bitumen

Abstract

Up to date, mainly temperature or UV light is incorporated into laboratory bitumen ageing procedures. However, the impact of visible light showed some interesting results recently. Therefore, an unmodified binder was exposed to a combination of temperature and different sun and narrow UV and blue light lamps. The aged binders were analysed with Fourier Transform Infrared (FTIR) spectroscopy, dynamic shear rheometer (DSR) and SARA fractionation. The results showed synergistic effects between temperature and light. Surprisingly, different lamp intensities lead to almost the same level of ageing, indicating that merely a certain amount of photoenergy is needed. Lastly, comparing the UV and blue light domain to sunlight showed that while exposed to the same amount of photoenergy, its effect on rheology differs, where sunlight showed the most impact on ageing. This highlights the importance of sunlight to the ageing process to sufficiently understand its combination with other ageing inducing factors.