Cracks Classification using Acoustic Emission Technique on a Reinforced Concrete Beam

The usage of non-destructive techniques for structure's state assessment is highly desirable because they offer the possibility to monitor continuously and in a non-invasive manner the sign of failures of any structure. Among the several techniques proposed over the years, Acoustic Emission (AE) seems very promising. Such a technique, which applies to various materials, consents to the evaluation of micro-fractures generated during failure by detecting their acoustic emission through sensors located on the surface of the material itself. Concrete beam failure is suitable for such kind of procedure. It has been widely investigated through AE, but despite the many literature contributes, there still is a scarcity of practical applications on real structures, and no consensus on protocols. In this work, an AE technique has been paired with a four-point bending test to try and find a robust and reliable experimental setup for AE application on concrete beams. Results show a proper classification of the occurring cracks, which change according to different zones of the concrete beam and different load values. Axial crack signals exhibit different features concerning shear crack ones. In such a way, the categorization of damages can be performed and crosschecked with the theoretical expectations. All these results suggest that the proposed setup can be used as a possible protocol for practical AE measurements.