Effect of Rest Period on the Fatigue Characteristics of Unmodified and Modified Bitumen

Bituminous binders are susceptible to structural damage caused by repeated traffic loading. However, these binders have demonstrated a remarkable ability for self-healing during the resting periods that follow loading, wherein they partially regain their initial stiffness and strength. This highlights the importance of the rest period in influencing the fatigue performance of bituminous pavement. Despite numerous research discussions focusing on investigating fatigue in bituminous binders with a rest period, the topic still needs to be explored. Therefore, a laboratory investigation was conducted to examine the fatigue of the binder under the influence of a rest period of loading. One unmodified binder of VG30 grade, one plastomer-modified binder, and one elastomer-modified binder were used for the experimental investigation. A time sweep test was performed at different strain amplitudes and temperatures on both unaged and long-term aged samples, incorporating a rest period, to demonstrate the impact of strain amplitude, temperature, and modifiers on the healing potential. The healing capability of bituminous binders is assessed through healing indexes obtained from experimental results. A comparison of fatigue life is conducted, examining the impact of rest periods using the normalized modulus. Aged binders exhibit a lower healing index than unaged binders. The healing index decreases with an increase in strain amplitude. The healing index decreases with decreasing temperature, signifying that the beneficial effect of the rest period diminishes as the temperature decreases.