Study Of Micromechanical Parameters Of Asphalt Mixture With Vacuum Compaction Condition

Compaction is one of the main influencing factors for low asphalt pavement performance and short service life.The compactness and smoothness of asphalt pavement are relied on different compaction technologies.In order to improve the quality of asphalt pavement compaction, a vacuum compaction technology is put forward and based on the asphalt pavement compaction mechanism.To evaluate application advantages of vacuum compaction technology used in asphalt pavement compacting process,this paper has studied and constrasted the micromechanical parameters of asphalt mixture in vacuum compaction condition and conventional compaction condition(non vacuum compaction) based on discrete element method.Firstly, this paper analyses the contact characteristics of aggregate element and asphalt element in asphalt mixture based on the discrete element method and the theory composition structure of asphalt mixture.And then the two-demensional discrete element models of asphalt mixture are established by the paralle-bond model,and the initial mechanical properties of asphalt mixture model are analyzed.Secondly,the volume parameters of asphalt mixture under the different vacumm degree compaction conditions are determined through test. The vacumm compaction specimen and conventional compaction specimen are distinguished by using void and voids in mineral aggregate as standard,and then the vacumm compaction specimens and conventional compaction specimens are optimized.They are the contrast samples,the vacuum degree is respectively 0.08 MPa and 0 MPa.Through the asphalt mixture splitting test,the macro-mechanical behaviors of contrast samples are compared and evalulated.Finaly,the discrete element method simulation models of vacumm and conventional compaction asphalt mixture based on volume parameter are established.and the splitting test and uniaxial compression test of asphalt mixture model are simulated.The mechanics characteristics of asphalt mixture model are researched and compared,which include the particle movement characteristics of the model,the properties of contact force chains between particles,the properties of parallel bond force chains between particles,the change rules of model internal crack and the rule of stress and strain in model.The research results indicate that different vacumm degrees have different impact on volume parameters and splitting properties of asphalt mixture.The simulation results indicte that the relative mechanical parameters of vacuum compaction model are superior to conventional compaction model’s corresponding mechanical parameters.And the mechanical properties and movement rules of aggregate element in vacuum compaction model and conventional compaction model are visually analyzed.