The Micromechanical Model Of Asphalt Mixture Considering Inter-Particle Interaction

Asphalt mixture is a special kind of heterogeneous composite consisting of asphalt binder, aggregates, asphalt-aggregate interphase, microcracks and voids. The mechanical properties of asphalt mixture are closely related to the complicate internal structure, which depends on the various raw materials’ properties, shapes, sizes and proportions. Traditional research techniques on the mechanical properties and damage mechanisms of asphalt mixture include the continuum mechanics and macroscopic tests. These macroscale based methods fail to reveal the microstructure related failure mechanism of asphalt mixture, such as the formation and propagation of micro-cracks, the micro damage caused due to the heterogeneous material, and the local failures caused due to the stress concentration. The micromechanical model of asphalt mixture can build up the quantitative relation of various macro performance and microstructure, and is of great significance to the multiscale analysis and detail design of asphalt pavement materials.In order to establish the exact micromechanical model of asphalt mixture in this paper, it first reviewed the advances in the micromechanics modeling of asphalt mixture and summarized the key technical problems in the modeling process as the solving of four mechanical problem, which were the particle effect, the size effect, the interface effect and the viscoelastic effect. Secondly, 5 common used micromechanical models were selected to conduct the multiscale applicability validation for asphalt mixture across the whole frequency domain. It also analyzed the importance of considering inter-particle interaction in the modeling process of asphalt mixture. Thirdly, it simplified the J-C model by introducing a parameter representing the overall strength of inter-particle interaction. And by virtue of elasticviscoelastic corresponding principle, it provided the effective complex shear modulus prediction model for asphalt mastics. Finally, it proposed two radial distribution assumptions to characterize the microstructure of asphalt mixture, which were the uniform distribution and the P-Y distribution, and deviated the effective modulus predicting formulas of J-C model under two different assumptions. By assuming asphalt mortar as the matrix phase and coarse aggregates and voids as the reinforcement phase in the asphalt mixture composite, and employing the stepping approach and elastic-viscoelastic corresponding principle, it established a two-step approach for the prediction of asphalt mixture effective dynamic modulus that capable of considering inter-particle interaction.Results show that compared with traditional models, the micromechanical models proposed in this paper have better accuracy for the prediction of effective viscoelastic modulus for asphalt mastics and mixtures. The establishment of the micromechanical model considering inter-particle interaction lays the foundation for further research improvements on asphalt mixture micromechanics.