Investigating the effect of ultraviolet aging on the healing capacity of bitumen containing taconite tailings

Abstract

ABSTRACT Bitumen’s evolution during aging includes oxidation, aromatization, chain scission, and carbonation, which alter bitumen’s properties of diffusivity and thermal conductivity and consequently bitumen’s healing capacity. To improve bitumen’s healing capacity after aging, there is a need to revitalize aged bitumen and restore its properties. This study studies the effect of ultraviolet (UV) aging on the healing capacity of bitumen containing different dosages of taconite tailings (a material with metal oxide as its main component). In addition, it examines whether the healing capacity of aged bitumen can be restored post-aging with the help of a rejuvenator made from waste vegetable oil. A healing index was used to measure the evolution of healing capacity in bitumen samples during aging and rejuvenation, using rheometry and spectroscopy. The study results show that exposure to UV aging increases the chemical aging index and rheological aging index, which makes bitumen stiffer and increases bitumen's complex modulus. This study further shows that taconite tailings accelerate the aging process of bitumen and increase its thermal conductivity. It was found that despite the negative effect of taconite tailings on bitumen aging, the presence of taconite tailings increased the healing capacity of bitumen. Results showed the healing capacity of bitumen containing taconite after being exposed to UV aging for 100 h and 200 h was up to 55.09% and 53.53% higher than that of bitumen without taconite, respectively. The samples with a higher content of taconite showed a higher healing capacity. Also all samples regardless of taconite dosage had higher healing capcity when rejuvnetor was present.