Study on Morphological Parameters of Hysteretic Curve of Dynamic Resilient Modulus

Abstract

The hysteresis curve of dynamic resilient modulus (DRM) is the load and deformation curve of asphalt mixture under dynamic loading, it can reflect the evolution rule of internal stress–strain state with load and temperature. Based on viscoelastic theory, three morphological parameters could be determined: slope k of major axis, eccentricity e of ellipse, and area S of HC, which characterizes DRM, viscosity, and energy dissipation capacity of asphalt mixture respectively. Thus the DRM tests under various temperatures and loads are carried out. The result shows that there is a significant difference in the morphological parameters of SBS and asphalt mixture No. 70 with the increase of temperature, and an inflection point exists at 15°C–20°C in both hysteresis curves, the values of k and S change regularly but e keeps unchanged as load level increases. It indicates that (1) asphalt quality has more influence on the property than grade, and the viscosity is unrelated to load size; (2) between 15°C and 20°C, the mechanical properties of asphalt mixture vary greatly, and their sensitivity to temperature are higher; and (3) different values of morphological parameters of HC reflect the performance difference of asphalt mixture, and three morphological parameters could be used to evaluate the basic mechanical performance of asphalt mixture include viscosity, fatigue durability, etc. Finally, based on the changing rule of test curves, the stress dependence model of resilience modulus which reflects the response behaviors of asphalt mixture under various stress level conditions is established, and the prediction results are close to the real state. The variable load cumulative dissipation energy prediction equation is derived based on the Miner linear damage criterion, and the fatigue equation based on the theory of energy dissipation is established. The morphological parameters S obtained by the dynamic modulus test can be used to predict the fatigue performance of asphalt mixture.