Study On The Mechanism Of 3D Porous Graphene In SBS/Crumb Rubber Blend-Modified Asphalt

Styrene-butadiene-styrene block copolymer(SBS)/crumb rubber blendmodified asphalt has been widely concerned by many road researchers due to its great environmental and economic benefits,but the inherent incompatibility of SBS and crumb rubber in the matrix of asphalt leads to inevitable phase separation,which extremely reduces the pavement performance and seriously restricts its development and application in pavement engineering.Graphene is a two-dimensional carbon nanomaterial with excellent performance,while its special structure and physical and chemical properties are expected to solve the shortcomings of SBS/crumb rubber blend-modified asphalt.Although graphene has been proved to significantly improve the pavement performance of modified asphalt,the mechanism of graphene is still unclear due to its different structure and surface chemical state,which has become a key scientific problem restricting the application of graphene nanomaterials in road engineering.Therefore,in this work,we focused on the complex blending system of SBS/crumb rubber modified asphalt and systematically investigate the mechanism of 3D porous graphene(3DPG)in SBS/crumb rubber blendmodified asphalt using a multi-scale analysis.First of all,five asphalt samples of SBS/crumb rubber blend-modified asphalt with different porous graphene contents were prepared.Secondly,the pavement performance and rheological properties of these composite modified asphalts were comprehensively measured by dynamic shear rheometer and bending beam rheometer.And then,the many advanced microscopic characterization equipment,such as Scanning Electron Microscope(SEM),Fluorescence microscope(FM),Atomic Force Microscope(AFM)and so on,were used to characterize the micromorphology,microphase structure and nanomechanical properties of these asphalt samples.Finally,combined with macroscopic mechanical tests and microscopic characterization tests,molecular dynamics simulation and first-principles calculations were conducted to reveal the enhancement mechanism of 3D porous graphene for SBS/crumb rubber blend-modified asphalt.The results of pavement performance tests and rheological tests demonstrate that incorporating 3DPG can effectively improve the compatibility of SBS and crumb rubber in asphalt and thus significantly enhance the high and low temperature performance and fatigue resistance of the modified asphalt,compared with that without 3DPG.Theoretical calculations further reveal that the nanopores in graphene can endow graphene with electrophilic property,providing a capability of absorbing nonpolar molecules in asphalt while the nonpore part in graphene can interact with polar molecules by conventional π-πstacking.The two forces within graphene can break the original colloidal structures of asphalt,which is conductive to the homogenous formation of SBS network and swelling of crumb rubber in asphalt,significantly promoting the pavement performance of the modified asphalt.This work presents the great potential of 3DPG as new additive to solve the inherent incompatibility of SBS/crumb rubber blend-modified asphalt for high-grade pavement engineering,while propose a new insight of the appalment of 3D porous graphene in polymer composite materials.