| With the rapid development of civil aviation and the increase of the aircraft movements in China,the runway pavement durability of the airport had been requested higher qulity.The natural factors such as the large amplitude of the seasonal climate changes and solar UV radiation,and other factors like high temperature flow air spewed from the engine of flight,accelerate the aging of the airport asphalt pavement with more and more high frequency of flights taking offs and landings.These made the asphalt binder to become dry,brittle,hard,and led to thermal cracking,which appeared such as surface cracks,loose,peeling,pits and other problems.These were important factors that affected the performance and the service life of asphalt pavement of airport.Nowadays,aging test research cannot accurately simulate the actual process of pavement aging at home and abroad,there was also no appropriate model to combine the aging experimental data information and airport pavement actual aging mechanism.It is urgent to study asphalt aging mechanism and characteristics deeply and systematically,and to take appropriate mesures to prevent aging in order to improve the performance and safety of runway.Based on the complexity and difficulty of asphalt aging process,this study collecte and analyz the relevant aging information at home and abroad to study asphalt aging properties and mechanism,in order to establish the prediction model and method of the anti-aging performance of asphalt binder,and provide the basis and reference to improve the anti performance of asphalt runway pavement.The main contents of this paper are as follows:(1)Based on task decomposition of Multi-Agent simulation techology and the main factors that affect the aing of asphalt pavement,aphlat aging process were studied from two aspects which were thermal oxidative aging simulation and phlto-oxidative aging simulation.The simulation test methods were determined,and the test parameters were determined from the experiment theory,equipment requirements and the purposes.(2)The simulation results of asphalt binders were analyzed.Using the Dynamic Shear Rheometer to do the dynamic frequency sweep test for different aged binders,it can obtain complex shear modulus and phase angle master curve of aphalt binders through the sigmoidal function and the nonlinear least squares method based on the Time Temperature Superposition.The asphalt materials information which was reflected from master curve of dynamic viscoelastic functions were analyzed.The crossover modulus of binders at different aging conditions can be obtained based on the mastercurve.Therefore,it would be found the relationships between the aging temperature and crossover modulus or the aging time and crossover modulus during analysis viscoelastic mechanical behavior in the aging process.(3)Based on the thermal oxidative aging simulation of asphalt,the aging path for unmodifed and modified asphalt binders and aging process were studied by dynamic frequency sweep test.Combined with the two stages reaction model and Arrhenius theory,the chemical group which are carbonly and cross modulus of asphalt binders at different aging temperature and time were analyzed.Therefore the fundamental reasons why asphalt viscoelastic properties were changing during the thermal oxidative aging were revealed.(4)The correlation between the carbonyl and cross modulus of asphalt binders was studied in order to find the relationship between the carbonyl and the crossover modulus.The crossover modulus oxidation model was established based on the crossover modulus of asphalt binders as the evaluation index of asphalt aging degree.(5)Based on the photo-oxidative aging simulation of asphalt,the aging of different kinds of asphalt binders at different intensity of UV radiation and aging time were analyzed and discussed.Therefore,the changing law of asphalt properties at UV radiation can be obtained,and the aging rate model can also be obtainded to predict anti ultraviolet aging properties of asphalt binders and provide theoretical basis and technical support.(6)Based on the asphalt aging performance simulation modeling technology,combined with model Christensen-Anderson of asphalt viscoelastic function master curve prediction research method,the asphalt master curve at different aging state can be obtained fast and simplely.It provided a reference for the evaluation and prediction of asphalt aging properties.The cracks of the asphalt pavement during aging can be further predicted,and the prediction of asphalt pavement performances such as rutting factor G*/sin?,fatigue factor G*sin?,asphalt mixture dynamic modulus E *,provided direction to improve the anti-aging performance. |
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