Evaluation of fatigue behavior in asphalt mixtures using bidirectional splitting and indirect tensile testing

ABSTRACT Fatigue damage in asphalt pavements is a critical issue affecting the durability and safety of road infrastructure. Traditional fatigue testing methods, such as the indirect tensile fatigue test, fail to replicate the alternating tension-compression stress fields experienced in real-world conditions, leading to inaccuracies in fatigue life predictions. This study investigates the bidirectional splitting fatigue test as an alternative method to better simulate the stress state of asphalt pavements. Using cylindrical AC-13 asphalt specimens subjected to varying stress ratios (0.3, 0.4, 0.5, and 0.6) at 20°C and 10 Hz frequency, the research evaluates vertical displacement trends and fatigue life. Results reveal that bidirectional splitting induces a more realistic stress response, with reduced permanent deformation and slower fatigue progression compared to indirect tensile testing. At lower stress ratios, bidirectional splitting enhances material durability by leveraging compressive stresses for crack healing, whereas higher stress ratios lead to shear failures. These findings underscore the bidirectional splitting test’s potential to improve fatigue performance assessment, paving the way for more resilient asphalt mixtures. The practical implications of these findings lie in their potential application to real-world pavement design and maintenance. Future research should explore its applicability to various asphalt types and real-world loading conditions.