Recovery of asphalt mixture stiffness during fatigue loading rest periods

Asphalt is a self-healing material that has the ability to restore part of its stiffness and strength during rest periods and elevated temperatures, leading to a significant extension in service life. The self healing of asphalt mixtures has been investigated in this paper using a modified tension-compression fatigue test. Asphalt mixture specimens, prepared with different binders (neat and SBS polymer modified) and gradations, were sinusoidally loaded in strain control mode, with a rest period being introduced at the end of each loading period. Rest period temperatures varied at 0, 10 and 20 degrees C. This loading-rest sequence was repeated three or four times. For some tests, the samples were loaded to complete failure after the final rest period. The asphalt mixture with the polymer modified asphalt had much better resistance to fatigue loading compared to the samples with neat binder. The stiffness of the sample represented by the norm of complex modulus (vertical bar E*vertical bar) showed an increase during the rest periods. The fatigue life in terms of number of loading cycles was higher with an increase in rest time temperatures. Moreover, the fatigue life values of the samples with rest periods were significantly higher than for continuously loaded samples loaded under the same conditions. (C) 2017 Elsevier Ltd. All rights reserved.