Modification of four-point bending test control system and development of laboratory asphalt mix fatigue prediction model

In this paper, the four-point bending beam fatigue test control system was modified after analyzing the factors affecting the accuracy of test results. Subsequently, a fractional factorial experimental design method named "uniform design" was applied on the development of laboratory asphalt mixture fatigue prediction model. The regression models expressing the relationships between the influence factors and initial flexural stiffness and fatigue life were established. It is pointed that the clamp load will significantly influence the four point bending fatigue test results. A changeable clamp load is also recommended in laboratory asphalt mix fatigue test. The regression results indicate that the consideration of asphalt content and air void in the asphalt fatigue prediction model is necessary.