Study On Aging Characteristics Of SBS Modified Asphalt And Mixture In High Temperature And Rainy Area

Although SBS modified asphalt is widely used,it has durability problems in the use period,and especially in high temperature and rainy areas.Aging deteriorates the technical performance of SBS modified asphalt,which ultimately has a great adverse impact on the road performance of asphalt mixture.In this paper,the aging characteristics of SBS modified asphalt and mixture in high temperature and rainy area are systematically studied through experiments.The effects of content of modifiers,machining parameters,types and contents of additives on the aging resistance of modified asphalt were analyzed through experiments.On this basis,thenon-linear differential aging equation and the aging rate equation were established.The aging rate parameter r is proposed to evaluate the anti-aging performance of the modified asphalt.According to the analysis of grey-catastrophe theory,under the condition of delayRTFOT test at 163℃,all technical indexes of SBS modified asphalt changed suddenly within 100 minutes of aging time,and different indexes had different sensitivity to asphalt aging.The Arrhrenius equation with viscosity as a parameter was established and it was found that the activation energy of the reaction increased with the extension of aging time.Through fluorescence analysis and IPP software quantitative processing,it was found thatthe area ratio and average diameterof SBS increased at first stageand then decreased with the extension of aging time.FTIR test showed that the main occurrence of asphalt aging wasoxygenation reaction,which results in BI index decreasing,CI and SI index increasing,and CI index had a good linear relationship with brookfield viscosity at 135℃.Through the DSR test,it was found that the rutting actor（G*/sinδ）increased signi icant y with the extension of aging time.The grey relation entropy methodanalysis found that the content of sulfoxide group and carbonyl group had a great influence on rheological properties of SBS modified asphalt.The results of DMA analysis showed that glass transition temperature T_g can be used as an evaluation index of low temperature performance of modified asphalt,and had a good linear relationship with ductility.The aging of asphalt results in the decrease of adhesion,which can be quantitatively evaluated by photoelectric colorimetry and surface free energy theory.With the extension of aging time,the adhesion rate of SBS modified asphalt and aggregate gradually decreased,The contact angle between SBS modified asphalt and test liquids increases gradually,and the surface free energy and its component decreases gradually.According to the change of the peak at 3300cm^-1assigned to hydroxyl stretching vibrationof the water molecules in modified asphalt,the diffusion process of water in asphalt film is divided into two stages,and aging caused the diffusion coefficient of the first stage to gradually increase.With the deepening of the aging degree of SBS modified asphalt mixture,the dynamic stability and complex stability index,maximum load,flexural tensile strength and bending stiffness modulus are gradually increased,the maximum bending strength,residual stability andintensity ratio of frozen and melted is gradually decreasing.The fatigue properties of asphalt mixtures with different aging degrees can be characterized by fatigue equation g-n/s.The fatigue life of the aged asphalt mixture is more sensitive to the change of the stress ratio,and the durability is deteriorated.