Ultraviolet Aging Mechanism of Asphalt Molecular Based on Microscopic Simulation

In order to reveal the nature of the Ultraviolet aging(UV-aging) behavior of asphalt molecules, simulation by Materials Studio software. The effect of UV aging on the transformation, aggregation and motion state of asphalt microstructure is analyzed by the changes in energy, density of dispersive phase, glass transition temperature and viscosity of the asphalt molecular system. The results show that UV aging enhances the bonding degree of asphalt molecules by increasing the heavy components in the asphalt molecules and increasing the distribution width between the asphalt molecule components, which improves the high-temperature resistance of asphalt. At the meantime, the UV aging causes the asphalt molecular movement state to solidify at low temperature so that the rheological behavior is difficult to occur by reducing the lightweight component and free volume of the asphalt molecule and increasing the glass transition temperature, which reduces the low-temperature resistance of asphalt. In addition, among the factors affecting the viscosity of asphalt molecular, the degree of influence of the molecular structure and molecular weight is significantly greater than the molecular activity. The addition of short branched chain hydrocarbon molecules to the UV-aged asphalt molecules could effectively reduce the viscosity of the asphalt molecules and improve the flowability of the asphalt molecules. The results of the study contribute to the understanding of the characteristics of changes in the microstructural pattern and dynamic behavior of asphalt molecules during UV aging, and achieve interpretation and prediction of changes in asphalt properties at the microscopic level.

Physical and anti-aging characteristics of nano-TiO2/irganox 1010 composite modified asphalt

Asphalt aging is the main cause of fatigue failure from asphalt pavements, and it can be divided into thermaloxidative and ultraviolet (UV) aging. In this study, nano-TiO2/Irganox 1010 were added to neat asphalt to simultaneously improve the aging phenomenon of asphalt in a variety of complex conditions of asphalt. We then analyzed and discussed physical properties of nano-TiO2/Irganox 1010 modified asphalt composites. In addition, MSCR (Multiple Stress Creep Recovery) and DSR (Dynamic Shear Rheometer) rheological tests were performed on nano-TiO2/Irganox 1010 modified asphalt with different contents. Aging simulation of nano-TiO2/Irganox 1010 modified asphalt was conducted through the TFOT (The Thin Film Oven Test) and UV test, and microstructure of UV aging was analyzed through scanning electron microscopy. Data analysis showed that the nano-TiO2/Irganox 1010 increased softening point and reduced penetration (25 °C) and ductility (5 °C). The nano-TiO2/Irganox 1010 also improved the creep resistance and rheological properties of the composites. Finally, the analysis of test results under different conditions showed that the addition of nano-TiO2/Irganox 1010 significantly enhanced the ability of asphalt to deal with aging in a variety of complex environments.

Study on Ultraviolet Aging Mechanism of Carbon Nanotubes/SBS Composite-Modified Asphalt in Two-Dimensional Infrared Correlation Spectroscopy

In order to explore the influence mechanism of carbon nanotubes on the ultraviolet (UV) aging properties of the SBS-modified asphalt binder, the changes of functional groups in the one-dimensional infrared spectrum and two-dimensional infrared correlation spectrum are studied in this paper. The results show that the UV aging process of the SBS-modified asphalt binder is the process of alkane chain cleavage and reorganization, the formation of oxygen-containing functional groups and decomposition of SBS. The incorporation of carbon nanotubes can reduce the mutual conversion of methyl and methylene functional groups, inhibit the decomposition of butadiene and the destruction of C = C double bonds in SBS. The degradation of SBS during the process of UV aging leads to the change of many functional groups and acceleration of the aging of the SBS-modified asphalt binder. The addition of carbon nanotubes can effectively alleviate the degradation of SBS and the formation of oxygen-containing functional groups at the early stage of UV aging, and reduce the influence of these two changes on other functional groups; thus, improving the anti-aging performance of the SBS-modified asphalt binder.

Aging Characteristics of Asphalt Binder under Strong Ultraviolet Irradiation in Northwest China

Asphalt pavement is significantly affected by ultraviolet (UV) aging. Therefore, the establishment of an asphalt UV aging evaluation system is desirable for highway construction in areas which experience strong UV radiation. In this study, Dunhuang City in Gansu Province (northwest China) was used as the research site. Base and SBS modified asphalts were selected, and their performance changes before and after UV aging were studied. An asphalt UV aging evaluation system was established, including the conditions for an indoor, accelerated UV aging test as well as evaluation indicators. The results showed that the adverse effect of UV aging on asphalt performance was greater than that of RTFOT and PAV, and that the low-temperature performance of asphalt degraded most rapidly. SBS modified asphalt was more resistant to UV aging than base asphalt, while 60/80 pen grade base asphalt was found to be unsuitable for use on pavements which are exposed to strong UV radiation. The residual penetration, penetration attenuation index at 25 °C, and residual ductility of the asphalt were used as indicators to characterize the aging of asphalt, while the fracture energy method was used as a supplementary evaluation method.