Study On Mechanical Properties Of Asphalt-Mineral Aggregate Interface Based On Molecular Simulation Technology

In the past 40 years,China’s road engineering construction technology has made significant accomplishments,and the national road network has been formed and is playing an important role.Durability of asphalt pavement is a particularly important and continuously concerned scientific problem in the course of road engineering.The mechanical properties of the asphalt-mineral interface play an important role in the road performance of the entire asphalt mixture.Moreover,asphalt-mineral aggregate interface is seriously damaged in the northern cold region,which has been an important research direction in the field of asphalt mixture durability for a long time.In this paper,a series of studies on the mechanical properties of asphalt-mineral aggregate interface were carried out at the atomic and molecular levels,aiming at analyzing the effects of asphalt aging and modifier types on the mechanical properties of asphalt-mineral aggregate interface.Combined with the macroscopic performance test of asphalt mixture,the adhesion property of asphalt-mineral aggregate interface,mechanical property and pavement performance of asphalt mixture under different low temperature conditions were analyzed.Furthermore,the key factors affecting the mechanical properties of asphalt-mineral aggregate interface in cold region are determined,which can provide effective support for improving the mechanical properties of asphalt-mineral aggregate interface in cold region.CNOOC 90# asphalt and Panjin 90# asphalt are selected as samples to conduct short-term aging and long-term aging treatment,respectively.SBS modified asphalt,rubber powder modified asphalt,and SBS/rubber powder composite modified asphalt with reasonable mixing amount are taken as the research objects.Based on the molecular simulation technology,the asphalt molecular model,modifier molecular model and mineral aggregate molecular model with different aging degrees were established,and the asphalt-mineral aggregate interface molecular model was constructed.Based on the calculation of micro-interface energy between each component of asphalt and mineral aggregate,the effect mechanism of asphalt component characteristics on the micro-adhesion of asphalt-mineral aggregate interface under different low temperature conditions was obtained.Secondly,the micro-interface energy of asphalt and mineral aggregate with different aging degrees and different modifier types was calculated.The adsorption law of asphalt and mineral aggregate was determined by the mean square displacement and concentration distribution of different asphalt on mineral surface.Based on the micromechanical properties of different asphalt,the elastic modulus,volume modulus and shear modulus were calculated,and then the influence of asphalt aging and the type of modifier on the microadhesion parameters of asphalt-mineral aggregate interface in cold region was determined.Through the contact angle test and low temperature trabecular bending test of asphalt mixture for six kinds of aging asphalt and modified asphalt,the adhesion work of asphalt-mineral system,bending tensile strength and bending strain of asphalt mixture are obtained to evaluate the adhesion of asphalt-mineral interface and the mechanical properties of asphalt mixture at low temperature.Grey correlation analysis and multiple regression analysis were used to explore the correlation between the micro-interface energy of asphalt-mineral mixture and the mechanical evaluation index of asphaltmineral mixture,and the relationship between the micro-factors and macro-variables was predicted,which further verified the feasibility of analyzing the mechanical effect of asphalt-mineral mixture interface with molecular simulation technology in cold region.