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Cement-stabilized macadam is a type of heterogeneous and discontinuous material. To study the mesomechanical behavior of cement-stabilized macadam particles, a discrete-element model of cement-stabilized macadam is constructed according to the random distribution theory and certain porosity and gradation. The constitutive relations of contact between particles may be linear contact, linear bonding, and linear parallel bonding. The stress–strain, crack propagation, particle velocity, stress transfer, and force chain distribution of cement-stabilized macadam were analyzed after comparing the results of simulated uniaxial compression with laboratory tests. The results of uniaxial compression calculations for cement-stabilized macadam were in good agreement with the experimental data. At the beginning of loading, the upper/lower particles moved toward the middle; at the peak loading stage, the particle movement was mainly in the vertical direction; and at the final of loading, the particles mainly moved to the sides. With the increase in loading, the contact force between particles became larger and larger. At the loading peak, the contact force between particles reached the maximum value, and the normal and tangential contact forces of particles were not evenly distributed. Microcracks at each stage were mainly vertical cracks, most of which were located at 70–110°. In this paper, the uniaxial compression test of cement-stabilized macadam was dynamically simulated using discrete-element theory, and the mesoscopic structure and dynamic variation process of parameters were analyzed. It provides references for the study of damage of heterogeneous and discontinuous quasi-brittle materials. [ABSTRACT FROM AUTHOR]

Water can cause a certain degree of damage to cement-stabilised macadam (CSM), and the degree of damage is greater if CSM is immersed in water for a long time. In order to study CSM damage after lengthy water immersion, a discrete-element model of CSM was established. The Weibull distribution function was used to simulate the heterogeneous contacts between particles. The parallel bond model was used to simulate the material constitutive relationship. The microscopic parameters of CSM were obtained by trial-and-error method. The stress–strain curve was obtained from immersion tests. The micromechanical behaviour of the CSM after immersion was analysed. The results showed that the contact area and strength of the CSM immersed for 30 days were, respectively, 31.4% and 46% less than those of the non-immersed macadam. The force chains between particles were evenly distributed. At peak loading, the normal contact force between particles was much larger than the tangential contact force, and the vertical force chain was much larger than the transverse force chain. The distributions of cementation energy, friction energy and impact energy were not uniform in the middle/peak loading stage. [ABSTRACT FROM AUTHOR]

Cement-based composite is a kind of heterogeneous and discontinuous material. It is not appropriate to conduct stress analysis on a model constructed by continuous mean theory when subjected to external loads. A granular flow model based on discrete element theory is constructed to simulate the dynamic process of cementstabilized macadam during uniaxial compression test in this article. The appropriate contact bonding model is selected, and the contact parameters are calibrated. After the uniaxial compression test in the laboratory, the relative displacement, stress transfer process and crack propagation between aggregate particles in the structure are verified by the results calculated by the model. It can be seen from the research results that the parallel bond model can well reflect the mechanical characteristics of cementstabilized macadam. In the process of the specimen being loaded, the vertical displacement between particles leads to the specimen being compacted, and the horizontal displacement between particles leads to the crack. The displacement angle of cementitious particles in the upper model is larger than that of coarse aggregate. The displacement angle of cementitious particles in the lower model is less than that of coarse aggregate. The particle displacement angle generally shows a decreasing trend. [ABSTRACT FROM AUTHOR]