Aging And Regeneration Of SBS Modified Asphalt Mixture

SBS modified asphalt mixture has been widely used in the construction of high grade highway.But in the course of road service,the function of environmental factors such as light,heat,oxygen will lead to the aging of mixture,which causes a series of diseases in the use of asphalt pavement.Therefore,the asphalt pavement needs repair or reconstruction after certain years,which will produce a lot of waste SBS modified asphalt mixture,how to deal with the waste SBS modified asphalt mixture has become a serious problem.In recent years,the aging and regeneration of waste SBS modified asphalt has become a hotspot in international road materials research.In this paper,SBS modified asphalt was treated with short-term thermal oxidative aging,long-term thermal oxidative aging and long-term Ultraviolet(UV)aging.Then regenerated with ordinary rejuvenator and reactive rejuvenator.Evaluate the effect of different aging and rejuvenator on properties of SBS modified asphalt through the test.SBS modified asphalt mixture was treated with the same conditions as SBS modified asphalt,then added the rejuvenator and new SBS modified mixture into the aged mixture.Evaluate the effects of different aging and regenerating methods on the road performance of SBS modified mixture.At last,the SBS modified asphalt binder was separated from those aged and regenerated SBS modified mixture.Physical properties of these SBS modified binder were tested.Infrared Spectroscopy and Fluorescence microscope were used to investigate the micro-structure of SBS modified asphalt binder.(1)The short-term thermal oxidative aging increase the viscosity,decrease the penetration,ductility and softening point of SBS modified asphalt.The long-term thermal oxidative aging and long-term UV aging increase the viscosity and softening point,decrease the penetration and ductility of SBS modified asphalt.The ductility decrease more than 80%.General rejuvenator and reactive rejuvenator can regenerate the physical properties of aging SBS modified asphalt,but under the same dosage,reactive rejuvenator effects significantly better than general rejuvenator,especially in ductility recovery.(2)Short-term thermal oxidative aging,long-term thermal oxidative aging andlong-term UV aging made the road performance of SBS modified asphalt mixture decreased.The water immersion stability,tensile strength ratio,flexural tensile strength and ultimate bending strength of SBS modified asphalt mixture decreased while the dynamic stability increased.immersion residual stability,strength ratio of freeze-thaw splitting,strength of flexural and decreases of ultimate flexural tensile strain,the moving stability increases.Short-term thermal oxidative aging has little effect on the road performance of SBS modified asphalt mixture.After the short-term oxidative aging,the water immersion stability decrease from 91.2% to 87%,while long-term thermal oxidative aging and long-term UV aging decrease to 61% and 68%.(3)After added into aged SBS modified asphalt mixture,the reactive rejuvenator can restore the road performance of the mixture.The road performance recovery tends to be stable when the dosage of reactive rejuvenator reach 12%.Regenerated the SBS modified mixture with 12% reactive rejuvenator,then mixed with newly prepared SBS modified mixture in different proportion.The road performance of regenerated SBS modified asphalt mixture increased with the increasing proportion of newly prepared mixture.The road performance of regenerated SBS modified mixture can meet the requirement of JTG E20-2011 when the proportion of newly prepared mixture was risen to 60%.(4)Seperated and tested the SBS modified asphalt binder of SBS modified asphalt mixture.Short-term thermal oxidative aging reduces the softening point,penetration,ductility and viscosity of SBS modified asphalt binder.The long-term thermal oxidative and long-term UV aging increase the viscosity and softening point while decrease the penetration and ductility of SBS modified asphalt binder.The reactive rejuvenator can significantly reduce the viscosity and softening point,improve the penetration and ductility of aged SBS modified asphalt and can restore the physical properties of SBS modified asphalt well;(5)The analysis of FTIR showed that in the aging process of SBS modified asphalt mixture,the characteristic peaks of C=C group decreased while the C=O group increased.After regenerated with reactive regenerator,the peaks of C=O group decreased while the peaks of S=O didn't change,the peakwhich indicates the C=O group in carboxyl had a reaction with reactive rejuvenator.(6)The Fluorescence Microscope analyses further show that the aging process of SBS modified asphalt mixture destroyed the structure of SBS modified asphaltbinder,the interface between SBS and asphalt disappeared.The the cross-link structure of SBS modified asphalt binder appear again.which indicates the reactive rejuvenator react with the oxidation product of SBS,restore the construction of SBS.