Corrosion of the reinforcement is a major degradation mechanism affecting durability and safety of reinforced concrete (RC) structures. As the corrosion process starts internally, it can take years before visual damage can be noticed on the surface, resulting in an overall degraded condition and leading to large financial costs for maintenance and repair. The acoustic emission (AE) technique enables the continuous monitoring of the progress of internal cracking in a non-invasive way. However, as RC is a heterogeneous material, reliable damage detection and localization remains challenging. This paper presents extensive experimental research aiming at localizing internal damage in RC during the corrosion process. Results of corrosion damage monitoring with AE are presented and validated on three sample scales: small mortar samples (scale 1), RC prisms (scale 2), and RC beams (scale 3). For each scale, the corrosion process was accelerated by imposing a direct current. It is found that the AE technique can detect damage earlier than visual inspection. However, dedicated filtering is necessary to reliably localize AE events. Therefore, AE signals were filtered by a newly developed post-processing protocol which significantly improves the localization results. On the smallest scale, results were confirmed with 3D micro-CT imaging, whereas on scales 2 and 3, results were compared with surface crack width measurements and resulting rebar corrosion levels.

中文翻译：

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通过 3D 定位钢筋腐蚀和相关混凝土开裂的钢筋混凝土退化监测

钢筋腐蚀是影响钢筋混凝土 (RC) 结构耐久性和安全性的主要退化机制。由于腐蚀过程从内部开始，可能需要数年时间才能在表面上发现视觉损坏，从而导致整体状况恶化并导致维护和维修的大量财务成本。声发射 (AE) 技术能够以非侵入性方式连续监测内部裂纹的进展。然而，由于 RC 是一种异质材料，可靠的损伤检测和定位仍然具有挑战性。本文提出了广泛的实验研究，旨在定位 RC 在腐蚀过程中的内部损伤。使用 AE 进行腐蚀损伤监测的结果在三个样本尺度上呈现和验证：小砂浆样品（尺度 1）、RC 棱镜（2 级）和 RC 梁（3 级）。对于每个鳞片，通过施加直流电来加速腐蚀过程。发现 AE 技术可以比目视检查更早地检测到损坏。但是，需要专用过滤才能可靠地定位 AE 事件。因此，AE 信号由新开发的后处理协议过滤，显着提高了定位结果。在最小尺度上，结果通过 3D 显微 CT 成像得到证实，而在尺度 2 和 3 上，结果与表面裂纹宽度测量和由此产生的钢筋腐蚀水平进行了比较。专用过滤对于可靠地定位 AE 事件是必要的。因此，AE 信号由新开发的后处理协议过滤，显着提高了定位结果。在最小尺度上，结果通过 3D 显微 CT 成像得到证实，而在尺度 2 和 3 上，结果与表面裂纹宽度测量和由此产生的钢筋腐蚀水平进行了比较。专用过滤对于可靠地定位 AE 事件是必要的。因此，AE 信号由新开发的后处理协议过滤，显着提高了定位结果。在最小尺度上，结果通过 3D 显微 CT 成像得到证实，而在尺度 2 和 3 上，结果与表面裂纹宽度测量和由此产生的钢筋腐蚀水平进行了比较。