Acoustic Emission and Ultrasound for Damage Characterization of Concrete Elements

The acoustic emission (AE) technique is widely used for real time damage detection in concrete. It uses stress waves emerging front nucleation and propagation of cracks recorded on the surface of the material by suitable sensors. In the present study, AE is used to monitor the deterioration progress of reinforced concrete beams subjected to four-point bending. The specimens consist of two layers of plain and fiber concrete. At different loading steps, ultrasonic pulse velocity measurements were also conducted to obtain the transient three-dimensional tomographic reconstruction of the internal structure. The AE source location is in good agreement with. the velocity structure visualization and the results are confirmed by visual observation of the actual cracks developed. The results show that the AE technique and velocity tomography are useful tools to study the failure progress of concrete.