On the existence of wax-induced phase separation in bitumen

In previous research efforts, it has been shown that at elevated temperatures, the wax content in bitumen does not have a significant impact on the rutting behaviour of asphaltic mixes. However, the presence of wax in bitumen does cause a physical hardening effect at lower temperatures, which encourages the propagation of cracks. Using waxy bitumen, asphalt mixtures tended to exhibit a higher fracture temperature. The study implied that the effect of wax on bitumen quality and asphalt mixture performance depended on many factors, such as precise chemical composition of the bitumen and particularly the nature of the wax. In the current paper, the discussion of the effect of wax on bitumen is continued. In this paper, atomic force microscopy and neutron scattering techniques are utilised to confirm the appearance of wax-induced phase separation and a new hypothesis is developed for its effect on the cracking and healing potential of the bitumen.