Transitions of component, physical, rheological and self-healing properties of petroleum bitumen from the loose bituminous mixture after UV irradiation

In the bituminous mixture, the petroleum bituminous film wrapped in the surface of aggregate is very thin, which is obviously different from the neat bitumen. In this research, the most commonly used dense bituminous mixture (AC-13) was designated for the ultraviolet (UV) irradiation simulation test. The loose bituminous mixture was exposed under the UV irradiation for 7, 14 and 28 days respectively, and the UV irradiation intensity was 21.0 w/m(2). After aging, the bitumen was recovered with the centrifuge separation method, the SARA components of the recovered bitumen (RB) was studied by the Thin-layer chromatography with flame ionization detection (TLC-FID). Meanwhile, the physical and rheological performance of the RB was investigated by the three major conventional indices and dynamic shearing parameters. In addition, the self-healing performance of bitumen was characterized by complex viscosity frequency-sweep test, capillary test and surface energy test before and after UV irradiation. The results show that with the extension of UV irradiation time, the chemical components of RB change obviously, which results in the deterioration of its colloid stability. Meanwhile, the physical and rheological performance of RB transitioned significantly (the decreases of penetration, ductility and phase angle of RB, and the increase of the softening point and complex modulus), indicates the RB becomes more embrittlement and hardening. Also, the worse flow behavior, the worse capillary fluidity and the lower surface free energy of RB result in the degradation of the self-healing performance of bituminous concrete.