Acoustic emission monitoring of the chloride-induced corrosion process in reinforced concrete

One of the main causes of deterioration in reinforced concrete (RC) structures is corrosion of the steel rebars. Therefore, efficient and reliable monitoring techniques are crucial to assess the damage. The acoustic emission (AE) technique is a promising non-destructive technique (NDT) to obtain such results. The initiation of new cracks and propagation of active cracks is accompanied by a release of energy, detected as an AE event, which contains information about the source. Damage can therefore be identified and located inside the concrete, even before cracks have reached the surface. Firstly, a brief state of the art review concerning AE-based corrosion monitoring in RC structures is presented. Parameterbased aswell as a signal-based approaches are reported. Secondly, an experimental program is presented that investigates a corroding RC beam with a length of 5 m. Chloride-induced corrosion of the rebars is achieved by an accelerated corrosion setup. The results of AE monitoring show the difference between the onset of corrosion and concrete cracking. Additionally, the corrosion level of the extracted rebars and leakage of corrosion products are linked to AE parameters and the location of the AE sources