Evaluation of stiffness to predict fatigue life of hot-mix asphalt - A Canadian case study

This study reports the relationship between the stiffness and fatigue life of hot-mix asphalt. Six different types of hot-mix asphalt mixtures were produced. The Superpave mix design method was followed for five mixtures; the remaining one mixture was designed using the Marshall method. The asphalt mixtures were tested for stiffness and fatigue life. The stiffness was measured with respect to resilient modulus and dynamic modulus. The dynamic modulus test was carried out at six different loading frequencies (0.1, 0.5, 1.0, 5.0, 10.0 and 25 Hz) and five different temperatures (-10, 4.4, 21.1, 37.8, and 54.4 °C). The fatigue life was determined by conducting the repeated flexural bending test. The regression analyses were performed to examine the relationships of resilient modulus and dynamic modulus with fatigue life. The results of regression analyses based on the data obtained through laboratory testing showed that resilient modulus did not have a strong relationship with fatigue life. In contrast, dynamic modulus showed a strong relationship with fatigue life for a number of loading frequencies and testing temperatures. It is also notable that the strong relationship between dynamic modulus and fatigue life was observed at higher testing temperatures of 37.8 and 54.4 °C. The overall findings suggest that the dynamic modulus at 5.0-25.0 Hz and 37.8 °C can be used to predict the fatigue life of hot-mix asphalt mixture.