Influences by air voids on fatigue life of asphalt mixture based on discrete element method

The paper studied the impacts of different air void parameters on the fatigue life of asphalt mixture based on discrete element method (DEM). By using discrete element software PFC3D (Particle Flow Code in Three Dimensions), virtual three-dimensional fatigue test was built according to the laboratory four-point bending beam fatigue test with stress-controlled loading mode. And the feasibility of virtual fatigue test was confirmed by laboratory testing data. Based on virtual fatigue test, the influences by content, distribution, size and orientation of air voids on the fatigue life of asphalt mixture were evaluated. It is found that, higher air void content leads to lower fatigue life of asphalt mixture especially when the air void content exceeds the designed air void content of asphalt mixture, interconnected air voids with bigger size is more harmful to the fatigue life of asphalt mixture than the independent air voids with smaller size especially when the orientation of air voids is parallel to the fatigue loading direction, and the non-distribution of air voids within asphalt mixture specimen also has important influences on the fatigue life of asphalt mixture especially for the variation of the air void distribution within the central-bottom section of asphalt mixture specimen. Thus, to guarantee the fatigue durability of asphalt mixture, it is important to improve the content, distribution and microstructure of air voids within asphalt mixture.