Combined usage of acoustic emission technique and ultrasonic pulse velocity test to study crack classification in reinforced concrete structures

This article aims to improve the knowledge on ‘crack classification’ in reinforced concrete (RC) beams using acoustic emission (AE) testing and ultrasonic pulse velocity (UPV) test. The present study reports on usage of AE and UPV testing methods on fracture mode in RC structures. Gaussian mixture modelling (GMM) method was used for crack classification. Support vector machine (SVM) method was used for separating AE data related to tensile cracking and shear cracking. It was observed that the UPV along the span of the RC beam reduced at places where cracks were formed. The locations in the RC beam where the cracks developed, an increase in the travel time between receiver and transmitter was observed. More AE hits were observed at locations where UPV value was less. It was observed that at 60–100% of the load, the RC beam with shear reinforcement exhibit higher shear hits (e.g. approximately 20–30%) while the beam without shear reinforcement exhibit much less, showing the effect of the shear stirrups. The RC beam without shear reinforcement failed more like a plain concrete beam due to tension. The observations made in this study provide a reference for conducting non-destructive testing of large RC structures.