Fatigue damage monitoring and analysis of aged asphalt concrete using acoustic emission technique

This paper presents an Acoustic Emission characterisation of the damage behaviour of asphalt concrete subjected to bending fatigue loading. An experimental campaign is carried out on an old asphalt concrete extracted from an in-service highway pavement, built-in 2001. Tests were performed in strain-controlled mode with an amplitude of 175 µstrain, a frequency of 25 Hz, and at 10°C. Failure criteria based on modulus decrease are analysed to determine the fatigue lifespan. Acoustic emission measurements are used to investigate the damage and failure processes. A network of eight piezoelectric sensors was used to acquire the acoustic signals. Therefore, different fatigue stages are identified based on the temporal evolution of acoustic activity. Hence, the event’s spatial location is presented to show the crack path propagation. The results show that sensors located at the bottom of the sample register more acoustic activity. The locations of acoustic events were in good agreement with the mechanical background calculations.