Healing during fatigue in 4 point dynamic bending tests

Describes a project concerning the healing phenomenon in the 4 point bending test during a fatigue test in controlled displacement mode. Rest periods between loadings (denoted as load blocks) ought to enlarge the fatigue life considerably. After a resting period the stiffness modulus is largely restored. If, instead of complete resting periods (no loading at all), pseudo resting periods (denoted as rest blocks) are used with a smaller load amplitude, it is shown that during these pseudo rest periods the stiffness modulus will initially increase. Depending on the duration of the pseudo rest period and the height of the amplitudes of the loadings within the rest blocks, this increase will be followed by a decrease in stiffness modulus. These findings confirm the opinion that healing already takes place during the fatigue process and should be taken into account in the interpretation of the fatigue measurements and the characterization of the fatigue properties. Based on the dissipated energy concept a model is proposed taking into account the healing phenomenon. This model should enable a more fundamental description of the asphalt fatigue properties including healing.