A micromechanics-based approach as an alternative to the experiment to characterise the fatigue behaviour of pavement materials

Pavement materials feature a heterogeneous microstructure, consisting of differently-graded granules randomly distributed in the material domain and/or connected by a binder matrix. This microstructural feature significantly contributes to the complicated fatigue behaviour of the materials when subjected to traffic loadings. Existing experimental methods for pavements have faced difficulties in controlling the material microstructure and its effects on the macro-behaviour. This results in scattered experimental data often observed in the fatigue tests of pavement materials, making it hard to characterise the material behaviour and quantify parameters for practical design. This paper presents a micromechanics- based numerical approach for characterising the fatigue behaviour of pavement materials. This numerical approach can physically reproduce the heterogeneous microstructure of the materials with different gradations thanks to the application of Discrete Element Method (DEM). Moreover, the incorporation of a damage-plastic contact model enables DEM to capture the fatigue behaviour of pavement materials. Through several numerical examples, the numerical approach is shown to predict well the fatigue behaviour and real crack development in pavement materials. Given its better controllable and cost-saving features, this numerical approach can be an effective alternative (to experiments) to assist engineers in the design of road pavements.