Evaluating the aging and fatigue performance of in-situ asphalt mortar through multiple stress creep recovery and energy-based methods

Abstract

This study investigates the viscoelastic and fatigue performance of in-situ asphalt mortar under various aging conditions, utilizing the multiple stress creep and recovery test combined with energy-based methods. The objective is to analyze the stress-strain responses and energy dissipation characteristics of asphalt mortars from surface, middle, and bottom pavement layers. Hysteretic curves were constructed for each mortar, and both energy dissipation (enclosed area) and slope (the reciprocal of the unloading slope) were calculated. Results indicate as service life extends, the hysteresis curves shift leftward, and the enclosed area decreases, signifying a decline in performance. For a given type of mortar, prolonged service results in a leftward shift of the curves and a reduced enclosed area. Both the dissipated energy and the slope exhibit degradation with increased service age. Notably, this degradation is more pronounced in surface layer, which show greater decay than middle and bottom layer. The middle layer's aging rate is less than 54 % of the surface layer’s characterized by dissipated energy and slope, suggesting slower aging dynamics and better long-term durability for the middle and bottom layers. Both dissipated energy and slope are effective indicators of asphalt pavement degradation. However, the 69 % decay difference in slope for the surface layer offers a more sensitive compared to the 2 % decay difference in dissipated energy. This work highlights the utility of MSCR and energy-based methods in evaluating the long-term performance of asphalt pavements.