Comparison of Different Micromechanical Models for Predicting the Effective Properties of Open Graded Mixes

ZOAB (Zeer Open Asphalt Beton) is the most widely used asphalt mixture in the Netherlands. As a type of open asphalt mixture, it is known to suffer from raveling distress. In order to analyze the propensity of raveling, micromechanical models are considered effective. However, most of the research work about micromechanical models has focused on dense asphalt mixture and the application of these models on ZOAB mixes has not been paid adequate attention. Therefore, in this research study, the performance of various micromechanical models for predicting mechanical properties of ZOAB was evaluated. The predicted results were compared with the measured values from a dynamic uniaxial compression test. The analysis results showed that none of the applied micromechanical models could obtain acceptable predicted results of the dynamic Young's modulus and phase angle of ZOAB. On one hand, the Dilute model, the Mori-Tanaka model, the generalized self-consistent model and the Lielens' model provided lower values of dynamic Young's modulus and higher values of phase angle, whereas, for the self-consistent model, the predicted results of dynamic Young's modulus were higher, and the values of phase angle were lower. On the other hand, the shapes of the predicted master curves of both dynamic modulus and phase angle of ZOAB could not match well with the experimental results. The further research on the differential scheme method showed that at lower frequencies the predicted mechanical properties of ZOAB mixes by the applied micromechanical models could not be improved even by following this scheme.