Multiscale Evaluation of Open-Graded Friction Course (OGFC) Asphalt Mixture Fatigue Damage

Research on the microscopic mechanisms of open-graded friction courses (OGFCs) is still in its early stages, and the specific effects of various factors on the fatigue performance of OGFCs have not been fully explored. This study investigates the effects of oil-stone ratios, void fractions, and maximum nominal particle sizes on the fatigue life of OGFCs at the macroscopic and microscopic scales. At the macroscopic level, indirect tensile fatigue tests were conducted on OGFC specimens. At the microscopic level, a three-dimensional (3D) reconstruction model of OGFC was developed using computed tomography (CT) and image processing techniques. Additionally, a 3D randomized aggregate model was developed using the Monte Carlo method and an aggregate random placement algorithm. Virtual splitting and fatigue tests were conducted to analyse the correlation between virtual and experimental macroscopic tests. The results showed that the splitting strength and fatigue life of the OGFC increased at higher oil-stone ratios but decreased at higher void fractions and larger nominal maximum particle sizes. The variation in the results of the virtual splitting fatigue tests derived from the CT reconstruction model and the experimental results was only 9–11%, indicating a strong correlation between the two approaches.