Study On Characteristics Of Asphalt Performance Under Different Ultraviolet Radiation Conditions

Asphalt as an organic pavement material is inevitably exposed to climatic conditions such as oxygen,water and sunlight in the period of the construction operation.These environmental factors will lead to a variety of physical and chemical reactions and the aging of asphalt.Aging makes asphalt became hard and brittle.Under the loading,it is easier to cause damage,which results in the decline of asphalt pavement performance and reduces the service life of pavement.However,the current understanding of the characteristics of asphalt performance variety under ultraviolet UV at home and abroad is still insufficient,which can not scientifically and accurately measure the impact of ultraviolet aging on asphalt pavement damage and damage.Therefore,it is necessary to systematically and thoroughly study the ultraviolet aging behavior of asphalt in order to better understand the aging mechanism of asphalt and provide decision-making basis for pavement maintenance management.This paper mainly studies the aging behavior of asphalt under different working conditions(different ultraviolet radiation intensity,different illumination time,different ultraviolet wavelength).Considering the adverse environmental effects during the operation of asphalt pavement,the coupling effects of UV-water,UV-salt and UV-acid are also studied in this paper.Firstly,the film oven test(TFOT)was used to simulate the short-term aging of asphalt material.And the aging samples of asphalt under different environmental conditions were prepared by the self-developed ultraviolet environment chamber.Then,dynamic shear rheological test(DSR),bending beam rheological test(BBR),four-component analysis and Fourier transform infrared spectroscopy(FTIR)were used to determine the rheological properties,composition and microstructure variety of aging asphalt in order to explore the characteristics of asphalt performance variety under different conditions.The results show that the complex modulus,rutting factor,and stiffness modulus(index)increase,the phase angle and creep rate(exponential)decrease after aging of asphalt under different conditions.The content of asphaltene in asphalt increases.And the content of aromatics and saturated fraction and colloid in asphalt decrease.It leads to the change from sol-type structure to gel-type structure,and the gel index increases.When chemical reactions occur in the molecules of the asphalt,carbonyl indexes and asulfoxide-based indexes increase in increasing of the carbonyl and sulfoxide-based absorption peak areas.The extension of UV radiation time and the increase of UV intensity accelerate the aging of asphalt.And the pattern of "the time and UV intensity equivalence" is followed in the process of aging of asphalt.Under the ultraviolet radiation,different water condition could accelerate the aging of asphalt.The test results under the given conditions in the paper show that the influence size is:UV-acid>UV-water>UV,UV-salt>UV-water>light.The shorter wavelength of UV radiation(365 nm)has a severer effect on the macro rheological performances,composition and microstructure of the asphalt.