| The aging and moisture damage of asphalt pavement in the process of construction and service are the main diseases that seriously affect the service life of the pavement.Based on the excellent anti-aging properties and strong adhesion properties of dopamine(DA),this paper explored the anti-aging properties of DA and the improvement of the adhesion between asphalt and aggregate,which was of great significance for prolonging the service life of asphalt pavement.In this paper,the DA modification conditions of montmorillonite nanocomposites were optimized first,and the effect of montmorillonite on the aging resistance of styrene-butadiene-styrene copolymer(SBS)modified asphalt under DA modification was studied under three aging modes.Then,the conditions of DA modification were optimized,and four kinds of modified asphalt were aged in different ways to study the effect of DA on the adhesion of asphalt aggregate system.The main conclusions of this study are as follows:(1)DA modification conditions affected the performance of montmorillonite.The results show that the distance between montmorillonite layers increased by 0.27-0.79 nm,and a layer of poly dopamine(PDA)film was attached to the surface and interlayer of montmorillonite by hydrogen bonding.After comprehensive comparison,the best modification conditions of DA modified montmorillonite were the concentration of 3mg/ml and the modification time of 0.4 h.(2)The rheological and anti-aging properties of SBS/montmorillonite modified asphalt show that three kinds of montmorillonite delayed the aging of asphalt and the degradation of SBS.Compared with SBS modified asphalt,the rutting factor aging index of SBS/dopamine modified montmorillonite(PMMT)composite modified asphalt decreased by 9.9%-31.0%under the aging effect,which was superior to other two kinds of montmorillonite composite modified asphalt.(3)The effect of DA modification conditions on aggregate performance.The results of scanning electron microscope(SEM)and X-ray diffraction(XPS)show that PDA film was formed on the surface of the aggregate after DA oxidation,and the thickness of PDA film increased with the increase of the concentration and time of modification.After comprehensive comparison,the optimum modification conditions of DA modified aggregate were selected as the modification concentration of 3 mg/ml and the modification time of 4 h under common deposition conditions.(4)The effect of DA on the adhesion performance between asphalt and aggregate.The results of photoelectric colorimetry and surface free energy test show that aging could increase the surface free energy of asphalt and accelerate the tendency of asphalt peeling off from the aggregate surface.DA could improve the adhesion between asphalt and aggregate.After DA modification,granite(G)could achieve the adhesion of unmodified limestone(L),which was conducive to the selection of aggregate types in the construction process.Based on the above analysis,the application of DA to asphalt and aggregate modification could effectively improve the anti-aging and adhesion properties of asphalt aggregate system,which is of great significance for prolonging the service life of asphalt pavement. |
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