Analysis Of Diffusion Fusion Mechanism Of Rubber Modified Asphalt Based On Molecular Dynamics Simulation

Rubber modified asphalt has been highly concerned by the road industry because of its good high and low temperature performance,skid resistance,good environmental benefits and low construction cost.With the rapid development of physics,chemistry and other related disciplines and the significant improvement of computer data processing ability,molecular simulation technology is more and more widely used in the research of asphalt materials.Considering the limitations of traditional analysis methods,this paper studies the diffusion and fusion mechanism of rubber powder modified asphalt from the microscopic point of view with the help of molecular dynamics simulation technology and micro observation methods.This paper takes rubber modified asphalt as the research object.Based on the four component experiment of asphalt,this paper constructs the molecular models of 70 matrix asphalt and 90 matrix asphalt with the help of Materials Studio,and constructs three rubber molecular models of SBR 1,SBR 2 and SBR 3 with styrene butadiene rubber,natural rubber and butadiene rubber in different proportions.After constructing the molecular model of matrix asphalt and rubber,the accuracy of the model is verified,and the asphalt-rubber diffusion model is constructed.The effects of total simulation time,asphalt type,different rubber composition types,temperature and asphalt four components on the diffusion behavior and compatibility of rubber modified asphalt are analyzed.At the same time,the effects of asphalt components,colloidal structure and other parameters on the diffusion and fusion process of rubber modified asphalt are analysed by means of scanning electron microscopy(SEM),fluorescence microscopy(FM),Fourier infrared spectroscopy(FTIR)and gel permeation chromatography(GPC)and so on.The results show that:at 180℃,the diffusion rate of 70 matrix asphalt is faster than that of 90 matrix asphalt,and the compatibility between 70 matrix asphalt and rubber is better than that of 90 matrix asphalt;at 180℃,the diffusion coefficients of the three rubbers in order of magnitude is SBR1>SBR2>SBR3,and in order of compatibility with the matrix asphalt is SBR1>SBR2>SBR3;the diffusion rate of the asphalt-rubber diffusion system generally increases with the increase of temperature,and the compatibility between matrix asphalt and rubber fluctuates with the increase of temperature;at 180℃,the order of diffusion coefficient of four components of asphalt is saturated>aromatic>colloid>asphaltene,and the order of compatibility with rubber is colloid>aromatic>asphaltene>saturated According to the results of the microscopic observations,the rate of desulphurisation and degradation of the rubber increases with increasing temperature;since the colloidal instability index of 70 matrix asphalt is lower and contains fewer benzene rings and branched chains,its diffusion rate is faster than that of the 90 matrix asphalt。...