Assessment of Post-Flooding Healing and Fatigue Life of Damaged Asphalt Concrete Mixes

Abstract: Climate change is increasing the frequency of extreme weather events, raising concerns about the resilience of pavement infrastructures under flooding. While surface-level water interaction with asphalt concrete (AC) is an immediate concern, elevated water levels can also increase moisture at the asphalt-subgrade interface, especially in full-depth asphalt pavements, which are prevalent in Illinois. The impact of moisture may vary based on the existing damage level in AC layers, as more damaged AC could be prone to water penetration and moisture-induced deterioration, as well as the saturation level reached within the AC mix during the flooding event. To explore these interactions, two typical AC mixes were compacted into beams and subjected to four-point bending fatigue tests at strain levels that induced damage levels of 90%, 75%, and 50% of the initial stiffness within a limited number of cycles. Half of the specimens served as a control, stored at room temperature between tests, while the remaining specimens were submerged in water for 72 hours (to simulate typical field saturation levels) followed by a 1-day drying period. This conditioning cycle was repeated two times, followed by a third cycle involving extended submersion (7 days) to simulate a more extreme saturation scenario. Statistical analysis revealed that both the number of conditioning cycles and the saturation level reached during the submersion protocol significantly influenced the stiffness outcomes of fatigue tests. Additionally, mixture and testing variables, including asphalt binder properties, number of load repetitions, and strain levels, were also impactful. The degree of damage, however, did not consistently increase susceptibility to moisture infiltration during submersion. At the most severe damage level (50% SR), specimens can show variable macro-cracking levels, as this stage represents only the onset of crack propagation, potentially resulting in more random healing behavior. Further investigation is necessary to clarify the interactions among these contributing factors.