| The aging process of asphalt will appear in the production and construction,and service under the impact of temperature,sunlight and oxygen after built up.Hardening of asphalt after aging bring about performance degradation and cracking and pits to asphalt pavement.Different thermal history and different combination of short-term and long-term history process,as well as two kinds of long-term aging process have different impact on performance of asphalt and its mixtures.So it’s of vital importance to study the influence of different thermal history on the property of asphalt for the prediction and prevention of asphalt pavement aging progress.The writer studied the change of SBS modified asphalt and its mixtures under different thermal history aging,and utilized macro and micro combined method to detect the variability and correlation of two kinds long-term aging way to the performance of asphalt.And the writer set different thermal aging conditions for the purpose of studying the evolution process of SBS modified asphalt,then predicted its viscosity after aging.The writer also studied the change law of integral SBS modified asphalt after different hot storage stability experiment time.The main conclusions of this paper is as follows:(1)Conventional technical indicators of SBS modified asphalt all decreased at a certain extent after different thermal history aging,specially for decline of ductility,increment of viscosity and decrement of fluidity.The aging degree of asphalt after PAV aging is obviously bigger than UV aging,and anti long-term UV aging property of SBS modified asphalt doesn’t show prominence evidently,SBS modifier has degraded seriously after UV aging.The average molecular weight increased after aging process,and bee-like structure on the surface of asphalt has been destroyed after aging.(2)It’s hard to accurately evaluate the property traits of asphalt after aging,and softening point isn’t proper for aging kinetics research any more.Aging kinetics model of SBS modified asphalt was obtained after kinetic parameter being substituted into the Arrhrenius equation,the viscosity obtained by aging kinetics model was accord with actual variation.(3)Integral ductility of SBS modified asphalt was better compared with blank sample after high temperature storage 48 h.And the anti-shearing deformation ability was enhanced by added the SBS modifier.The aging characteristics was not obvious after different storage time which is similar to the change of conventional technical indicators.(4)Synthesis of grading of AC-13 C was selected for asphalt mixture.The optimum asphalt content was 5.3% after asphalt mixture design experiment.Short thermo-oxidative ageing didn’t have much impact on the high and low temperature performance of SBS modified asphalt mixtures,and water stability decreased after aging process.Dynamic modulus of SBS modified asphalt mixture decreased with test temperature increased,and dependence of phase angle with temperature,loading frequency and degree of thermo-oxidative ageing is more complex. |
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