A new approach for the evaluation of time–temperature superposition effects on the self-healing of bituminous binders

The experimental work described in this paper investigated the coupled effects of rest time and rest temperature on the self-healing potential of bituminous binders. A set of neat and polymer-modified materials were subjected to self-healing tests that included two oscillatory shear loading phases separated by a single rest period. Multiple testing conditions were analyzed by combining various rest times and rest temperatures. Self-healing was quantitatively assessed by introducing two healing indices, based on the magnitude of stiffness and fatigue endurance gain, in which time-dependent artefacts were properly quantified and removed. Experimental results were found to be consistent with the kinetics of self-healing phenomena and underscored the importance of considering rest time coupled with rest temperature for a reliable evaluation of true self-healing properties. A new model was proposed to describe the self-healing performance of bituminous binders and self-healing charts were constructed from generalized logistic functions incorporating the effects of both rest time and temperature.