Kinematics of Corrosion Damage Monitored by Acoustic Emission Techniques and Based on a Phenomenological Model

Yuma Kawasaki, Tomoe Kobarai and Masayasu Ohtsu Journal of Advanced Concrete Technology, 10, 160-169, 2012 Corrosion of reinforcing steel bar is a critical issue in concrete structures. In response, a variety of techniques have been developed for early detection of corrosion phenomena, including nondestructive evaluation (NDE) techniques. Recently, we have reported that continuous acoustic emission (AE) monitoring is applicable to identify the onset of corrosion and the nucleation of corrosion-induced cracks due to the expansion of corrosion products. In order to clarify the kinematics of these AE activities in concrete, cyclic wet and dry tests on reinforced concrete beams were performed. The SiGMA (Simplified Green's functions for Moment tensor Analysis) procedure was applied to AE waveforms to locate micro-cracks and to determine kinematic information about crack types and orientations of corrosion-induced cracks. These results are visually confirmed through comparison with cracking mechanisms observed by a scanning electron micro-graph (SEM).

An early warning system for detecting onset and initiation of cracks due to steel corrosion including their locations using AE technique was developed. Though successful verifications were made with only a few tested beams in the laboratory, the proposed technique demonstrated a piece of pleasing innovation with future application potential for real structures.(Prof. S. Tangtermsirikul)