Study On Shear Modulus Of Asphalt Mixture Based On Particle Contact Characteristics

With the further development of transportation industry,the proportion of large and heavy vehicles has increased significantly,and the rutting problem of asphalt pavement has become increasingly prominent.The main reason of rutting in asphalt pavement is the shear deformation of materials.Deformation of asphalt mixture by the contact between the mineral aggregate,interface friction and sliding constraints,this topic is based on laboratory test,uniaxial penetration test,uniaxial compression test,particle interface shear test,etc.)and digital image processing technology,based on the theory of granular material mechanics model,the internal structure of asphalt mixture pavement particles contact characteristics of quantitative research,The existing shear modulus mechanics model of the mixture was optimized,and the shear modulus prediction model of the mixture with skeleton structure,asphalt performance and asphalt film thickness as the main parameters was established.The main conclusions of this study are as follows:(1)The results of interfacial shear tests show that the pressure area is correlated with the gradation,asphalt type and asphalt film thickness as follows: under the same asphalt and asphalt film thickness,he pressure area of AC-13 gradation is the smallest,and the pressure area of SMA-13 gradation is the largest.With the same gradation type,S-HV high modulus asphalt >SBS modified asphalt >70# road oil asphalt;The pressure area increases with the increase of asphalt film thickness.(2)The proportion of factors affecting tangential shear stiffness was studied by using grey relational degree analysis method.The order of main interface parameters was as follows: asphalt film thickness,dynamic viscosity,penetration degree,fractal dimension and softening point.Among them,asphalt film thickness ranks the second,and decreases with the increase of asphalt film thickness,which accords with the slip mechanism between interface particles.The influence of bitumen type on it is reflected by dynamic viscosity and penetration degree,while the fractal dimension representing gradation has no significant influence on it.(3)The influencing factors of tangential shear stiffness were discussed by means of grey relational degree analysis.The order of the factors was as follows: interfacial shear modulus,thickness of asphalt film,dynamic viscosity,penetration degree,shear displacement,fractal dimension,equivalent friction ratio,peak shear force,mean shear force,softening point and area.Among them,asphalt film thickness ranks the second,and decreases with the increase of asphalt film thickness,which accords with the slip mechanism between interface particles.The influence of bitumen type on it is reflected by dynamic viscosity and penetration degree,while the fractal dimension representing gradation has no significant influence on it.(4)The uniaxial penetration test and uniaxial compression test of asphalt mixture were carried out.On the basis of the existing shear modulus dynamics model of asphalt mixture,the analysis of particle contact characteristics was added to put forward a modified model of normal elastic stiffness,and the prediction model of shear modulus of asphalt mixture based on uniform strain assumption was optimized.