The Development of a Fatigue Failure Prediction Model for Bitumen Based on a Novel Accelerated Cyclic Shear Test

Fatigue failure of bitumen significantly influences the durability and service life of asphalt pavement. Current fatigue tests have drawbacks such as long durations, unrealistic traffic loading simulations, and difficulties of identifying failure mechanisms. Similarly, existing prediction models are often overly complex and inaccurate. To solve these drawbacks, in this study, a novel accelerated cyclic shear test in stress-controlled mode using a dynamic shear rheometer was introduced to evaluate the fatigue performance and reveal the fatigue failure mechanism of bitumen. The sigmoidal function was applied to develop a simplified fatigue failure prediction model for bitumen through stress and temperature shifts. The results demonstrate that bitumen's response under the newly proposed loading method aligns consistently with behaviour characteristic of a plasticity-controlled failure mechanism. The variable parameter load ratio significantly influenced the bitumen's time-to-failure, which increased as the load ratio decreased. Bitumen exhibited the longest time-to-failure when the load ratio (minimum stress/maximum stress) was 0.1. The developed model effectively predicted the time-to-failure of bitumen across different load ratios and under various temperature and stress conditions.