Surface Characteristics of Ageing Asphalt Binder Coupling Thermal Oxidation and Ultraviolet Radiation

Abstract

In this study, styrene-butadiene-styrene (SBS) modified asphalt binder was aged by thermal oxidation coupled with ultraviolet (UV) radiation. Fluorescence microscopy (FM), scanning electron microscopy (SEM) with energy dispersive x-ray (EDX) detector, surface free energy, optical technology, Fourier transform infrared spectroscopy, and dynamic shear rheometer were used to explore the surface characteristics and trace the chemo-rheological evolution of the asphalt binder at various durations of aging. Both FM and SEM could observe two phases of degradation of the polymer under thermo-oxidation. The surface of UV-aged asphalt binder produced more cracks, observed by FM and SEM, and bulged along these cracks and some fragmented blocks appeared. EDX results indicated that the oxygen content of the surface of the asphalt binder increased with increasing aging duration, leading to more oxygen-containing compounds, more carbonyl and sulfoxide groups, increasing polarity, and decreasing contact angle of water droplets on the surface of the asphalt binder. Coupled aging increased the reflectance in all regions from 200 nm to 2,500 nm, while thermo-oxidative aging alone increased the reflectance from 200 to 400 nm and produced the opposite result in the other region. With increased aging duration, UV-aged asphalt binder becomes brighter and thermo-oxidative aged asphalt binder becomes darker. The asphalt binder samples did not discolor much with varying aging duration, and the color difference was more similar than opposite. The results of testing chemo-rheological properties indicated that the addition of UV radiation significantly increased the stiffness and elasticity and produced more obvious effects on the surface characteristics of variously aged binders.

Effects of Environment-Friendly Rejuvenator on the Rheological Properties and Microstructure of Aged Asphalt

“…Compared with the continuous yellow-green fluorescence in modified asphalt, the SBS content in aged SBS-modified asphalt has been reduced to a very low level, and the number of SBS modifiers after aging has been greatly reduced. It can be inferred that the SBS triblock copolymer underwent severe chain scission after asphalt aging, which is consistent with the findings of previous studies ( 27 – 31 ). As shown in Figure 5 c , the SBS particulates in regenerated SBS-modified asphalt are significantly restored, and the distribution is closer to that of the original SBS-modified asphalt, where the SBS particulates are basically restored to the level when they were not aged.…”

“…The aging process of styrene-butadiene-styrene (SBS)modified asphalt involves both the aging of the matrix asphalt and the degradation of the SBS modifier, in which the oxidative degradation of the SBS modifier is an essential factor leading to the deterioration of modified asphalt performance (27)(28)(29)(30)(31). While the physical properties of SBS-aged asphalt can be improved to some extent by waste soybean oil, degraded SBS modifiers cannot be restored.…”

The Effect of Wetfix and Nanohydrated Lime Additives on Bitumen Aging and the Cohesion and Adhesion Failure Mechanisms of Hot Asphalt Mixtures

“…where Pa is air void in the asphalt mixture (%), Va is the void volume of the asphalt mixture (cm 3 ), E is the sample volume (cm 3 ), B is the weight of the saturated sample with a dry surface after saturating the sample with a vacuum pump (gr), and S is the sample saturation percentage (%). The samples were saturated and then transferred to an isolated plastic bag.…”

“…The thermaloxidative aging of bitumen occurs from the mixing stage to the end of pavement life. There are two phases for the thermal-oxidative aging of bitumen: one is short-term aging and the other is long-term aging [3]. Short-term aging occurs during asphalt mixture construction, while long-term aging happens during the pavement's service life.…”

Rheological Properties and Microscopic Characterization of Delayed Decay-Modified Asphalt Based on UV Ageing

“…Most of them are added to modifed asphalt to enhance its performance. Tere are relatively many studies on adding certain kinds of antiultraviolet additives to modifed asphalt to enhance its anti-ultraviolet ability, and there are many kinds of additives currently used to achieve the UV ageing resistance performance of asphalt [7,8]. Te study found that the addition of 0.8% carbon black can maximize the antirutting factor of asphalt [9,10].…”