Study On The Modification Mechanism Of Graphene Oxide Modified Asphalt And The Road Performance Of Warm Mixed Asphalt Binder And Mixture

With their special size effect and surface effect,nanomaterials can effectively improve the performance of asphalt,which are conducive to the current heavy traffic conditions and complex environmental conditions.At the same time,nano-material modified asphalt well solves the problems of segregation and aging during the production,storage and use of the polymer modified asphalt,and has become a hot spot and frontier of asphalt material research at home and abroad.As a carbon-based nanomaterial,graphene oxide(GO)with rich oxygen-containing functional groups on its surface,making it easily compatible with polymers and improving its thermal,mechanical,and tensile properties.In this paper,GO is used as a modifier to modify AH-70#base asphalt and SBS modified asphalt,and their performance and mechanism are studied.This paper systematically studies the effects of different GO contents on the conventional and rheological properties of asphalt binders.At the same time,in order to analyze the mechanism of GO on different asphalts at the macro/micro perspective,the components,colloidal structure,chemical characteristics(FTIR),thermal properties(DSC)and micro-morphology(AFM)of GO modified asphalt were studied.The results show that GO can reduce the penetration,increase the softening point,little change in ductility,and increase viscosity of asphalt.They show that GO can improve the high temperature stability of asphalt,but it has little effect on the low temperature crack resistance.The rheological performance test results show that GO can significantly improve the rutting factor,failure temperature,viscoelasticity,and rutting resistance of asphalt.The optimal amounts of GO for base asphalt and SBS modified asphalt are 0.05%and 0.2%,respectively.In addition,the results of component analysis show that the addition of GO can adsorb light components in asphalt,aggregate and transform into colloid and asphaltene,and improve the stability of its colloidal structure,thereby increasing its high temperature stability.FTIR analysis founds that the modification mechanism of GO includes both chemical reactions and physical blending for the non-modified binder,but only physical blending for the SBS-modified binder.DSC analysis shows that addition of GO into asphalt will not remarkably effect on the low temperature crack resistance of asphalt,but can significantly improve their crosslinking degree.AFM test shows that GO can significantly change the "bee" structure of asphalt,form a stable flaky fold structure,and increase their surface roughness.In order to adapt to the concept of resource conservation and green development advocated by modern society,and to improve the limitation of the application of GO modified asphalt,the warm mix additives(Sasobit and waste cooking oil(WCO)were used to modify GO modified asphalt,and their performances and mechanism was conducted.The study found that the addition of 3%Sasobit can improve the high temperature stability and resistance to permanent deformation of GO modified asphalt,but it has a negative effect on the fatigue performance and low temperature crack resistance of GO modified asphalt,while the effect of WCO is opposite.The use of 3%Sasobit and 5%WCO alone or in combination can significantly reduce the viscosity of GO modified asphalt,thereby reducing the mixing and compacting temperature of the asphalt mixture.FTIR results show that the modification mechanism of the AH-70#matrix asphalt binder by both GO and warm mix additive(3%Sasobit,5%WCO,or the mixture of these two)includes both chemical reaction and physical blending,and the warm mix addition can alter the hydrogen bonding between asphalt molecules.In addition,DSC analysis found that although Sasobit can increase the crosslink degree of GO modified asphalt,it will adversely affect its low temperature crack resistance,while WCO can increase the crosslink degree and low temperature crack resistance of GO modified asphalt at the same time.The dense-graded of AC-13C asphalt mixture was used to study the road performance of GO and warm mix additive(Sasobit,WCO or the mixture of these two)modified asphalt mixture.The results show that the addition of GO alone or in combination with Sasobit can improve the shear strength,permanent deformation resistance,high temperature stability and water stability of the asphalt mixture,but it will adversely affect its low temperature crack resistance,which the addition of WCO has opposite effect.The 0.05%GO+3%Sasobit composite modified asphalt binder(mixture)with excellent high temperature performance is suitable for hot southern climates.The 0.05%GO+5%WCO composite modified asphalt binder(mixture)with excellent anti-fatigue cracking performance and low temperature performance is suitable for cold northern climates.And the GO+Sasobit+WCO composite modified asphalt binder(mixture)with excellent high and low temperature performance is suitable for all regions.