Preparation And Properties Of Asphalt Modified With Graphene Oxide/Polyurethane Composite

As an important engineering material,asphalt has been widely used in the fields of industry,transportation and infrastructure construction.With the rapid development of the national economy,new demands of the asphalt quality are constantly put forward and the traditional ordinary base asphalt can not fully meet their needs.From the research,production and application of polymer modified asphalt to polymer composite modified asphalt,and then nano materials and techniques applied in asphalt modification,the research of modified asphalt is deepening and evolving.However,the contradictions of various types of modifiers in the asphalt performance improvement and modification costs affect their promotion and application.Graphene oxide(GO)and polyurethane(PU)were prepared through pressurized oxidation method and prepolymer method respectively,and then used as modifiers to prepare GO/PU modified asphalt.Nano effects and polymer advantages were synergistically functioned to improve the properties of base asphalt and asphalt mixture.A melting method of GO aqueous dispersion to prepare modified asphalt was proposed,and the modifying effect of GO on base asphalt was studied by Fourier transform infrared spectroscopy(FTIR)and the modified asphalt composition variation.It was found that GO contained same functional groups with base asphalt and chemical reaction was not existed in modification process,GO affects the properties of base asphalt with its own nano features.Furthermore,GO sheets hindered the components conversion in asphalt under high temperature and oxygen condition,and restricted the asphalt gel transition in the aging process which maintaining the excellent adhesion and temperature stability.Polymer nanocomposite modified asphalt method was put forward to prepare GO/PU modified asphalt.Firstly,GO/PU composite was prepared by in-situ polymerization,and then well-dispersed GO/PU composite was re-dispersed in base asphalt to prepared modified asphalt.Finally,GO and PU were uniformly dispersed in modified asphalt and achieved both polymer and nano modification effects.Macroscopic properties and microscopic changes of GO/PU modified asphalt were studied from mechanics,thermotics,physical-chemical structure and asphalt SARA(saturates,aromatics,resins and asphaltenes)components.The relationship between structure and properties of modified asphalt system was discusses and found PU and GO played their roles to improve the properties of base asphalt from the ways of "alloying" and"compositing" respectively.From GO modified asphalt,PU modified asphalt and then GO/PU modified asphalt,the effect of properties of GO and PU and their systematic function on the properties of base asphalt were systematacially studied.It was found that nanomaterials agglomeration can be effectibely avoided by masterbatch dispersion method.Based on the colloid theory and polymer chemistry,the modification mechanism was revealed from the aspects of modified asphalt components,colloidal structures and microscopic properties.In addition,the composites modifier formulation and the asphalt modification process were obtained for instructing production applications.Based on the maximum density curve grading theory,a coarse dense structure asphalt mixture was designed according to AC-13 gradation.Low-temperature bending and ordinary-temperature stress-strain nonliner viscoelastic behavior of asphalt mixture were analyzed through Hooke’s Law and corrected Nelson rheological model.Additionally,Kelvin viscoelastic model and Maxwell viscoelastic model were used to investigate the asphalt mixture’s creep deformation and the relationship between the loading frequency and the pavement deformation.Finally,the modification effect of polymer and nanomaterial in asphalt was described in organizational structure and failure mechanism aspects of the asphalt mixture.