Research On Characterization Of Asphalt And Asphalt Concrete Of Ultraviolet Ageing

Road transportation is the lifeline of national economy and social development. Up to the end of 2008,over 60.3 thousand kilometers high-grade highway pavement in China has been opened to traffic,which has gradually formed a traffic system of "encryption into a network of the eastern part of west central connectivity".The demand for a high standard pavement performance during the service period of highway pavement is increasing.Meanwhile,the pavement performance is apparently deteriorating with asphalt aging,volatile attenuation,natural hardening and asphalt flow.Among them,sunlight and oxygen are the main reasons for the degradation of asphalt pavement performance.This paper explored the influence of UV elements on asphalt property,as well as the changing rules of chemical components and construction of asphalt or asphalt concrete under the condition of UV aging.Based on the conclusion of previous research,choosing based asphalt AH70 and SBS modified PG76-22 as objects,the paper examined the indoor and outdoor aging of road performance,chemical composition,chemical structure and rheological properties with analyzing methods of Brookfield viscosity, four-component analysis,Fourier Transform Infrared(FTIR),Atomic Force Microscopy(AFM) and Dynamic Shear Rheometer(DSR),etc.The findings are as follows:the rules of indoor and outdoor aging are almost the same;oxygen aging makes the viscosity of asphalt road performance incresed and temperature sensibility decreased,the light components in asphalt decreased and colloid,asphaltene increased;at the same time,the index of carbonyl and sulfoxide-base ascended remarkably,leads to the formation of more asphaltene with comparatively bigger molecular weight;in modified asphalt PG76-22,the content of butadiene functional group has reduced with the decomposition of SBS modified;the UV action contributes to the increment of asphalt complex modulus G* and the reduce of phase angleδand makes asphalt stiffer;asphalt aging rises proportionately to the asphalt thickness,aging time and aging intensity.The paper inspected the property changes during the aging process by low temperature three-point bending test and four-point bending fatigue test,with SBS modified asphalt PG76-22,compound AC-13 and SMA-13 gradation asphalt concrete as materials.By conclusion,we find that the bending intensity rose at first and then fell with the reinforcement of aging extend.The higher the aging degree is, the faster the falling of bending intensity.The bending stiffness modulus of indoor aging exhibits a nearly same variation law with aging time.By caculating the bending fracture energy of specimens,asphalt is proved to have the biggest bending strain energy in short time aging or around 12 months service.We also find that the anti-aging and anti-fatigue properties of SMA-13 are superior to AC-13 gradation construction by a comparing research based on phenomenology and dissipative energy fatigue theories.The cumulative dissipated energy of materials varies directly with fatigue life,while the latter becomes shorter with the increment of aging time and strain.