Study On The Microscopic Mechanism Action Of Rejuvenator And Aged Asphalt

With the increasing of highway in China,highway maintance works have been greatly increased,and a large mount of reclimated asphalt pavement is produced during this process.The asphalt pavement regeneration technology which can reuse reclimated asphalt pavement could produce good social and economic benefits.However,the incomplete congnition to the mechanism of the action between rejuvenators and aged asphalt still restricts the application of regeneration technique,thus further study need to be executed to further understand the mechanism,and to improve the quality of recycled asphalt mixture.In this paper,artificial aged asphalt was used,and rejuvenated asphalt was preparation by adding rejuvenators to the aged asphalt.Dynamic shear rheometer(DSR),Fourier transform infrared spectroscopy(FTIR),gel permeation chromatography(GPC),surface free energy and atomic force microscopy(AFM)were used to study the change of rheological properties,chemical composition,adhesive and microstructure between the aging and rejuvenation process of asphalt.The research results show that the asphalt due to volatilization of smaller molecules and oxidation reaction in the process of aging,its molecular weight to the migration of large molecules,and generate material containing polar functional groups,results in the decrease of asphalt complex modulus increases,phase angle,namely becomes hard and brittle,and the adhesion between aggregate and reduced,water damage occurred more frequently.By adding the rejuvenator can adjust the molecular weight distribution of asphalt aging,enhance the capacity of asphalt molecular motion,thus reduce complex modulus of asphalt aging and phase Angle is reduced,and can effectively enhance the interface adhesion between asphalt and aggregate and spalling resistance,significantly enhance the water stability of asphalt mixture.The results of the atomic force microscope also show that the regeneration of asphalt can be regarded as the reverse process of aging at the micro level,and the nano adhesion force can be used as an index to evaluate asphalt adhesion.The three kinds of the rejuvenators used in this paper can be divided into two kinds by different mechanism of rejuvenation: one kind is light oil,through their own small molecular properties,filling the aging asphalt between macromolecules,lubrication,to enhance of the sport ability of the aging asphalt;the other is surfactant,which forms a layer of "interfacial film" between the soft asphalt and the asphaltene,thus achieving the aim of enhancing the mobility of the asphalt molecules.