Acoustic Emission Techniques for Rebar Corrosion in Reinforced Concrete

Abstract

Corrosion of reinforcing steel is modeled phenomenologically as corrosion losses of three phases. At the 1 st phase, corrosion is initiated in reinforcement. The rate of the corrosion loss decreases at the 2 nd phase under aerobic conditions. At the 3 rd phase of anaerobic corrosion, the expansion of reinforcing steel due to corrosion product nucleates concrete cracking. In order to identify the onset of corrosion and the nucleation of concrete cracking based on this model, continuous AE monitoring in reinforced concrete specimens was conducted in a cyclic wet and dry test. High AE activities were characteristically observed twice during the corrosion process. AE parameter analysis of hits, events and locations demonstrates that AE monitoring is readily applicable to detect the corrosion in rebar and to identify the corrosion process.

Non-Destructive Evaluation for Corrosion Monitoring in Concrete: A Review and Capability of Acoustic Emission Technique

“…The parameter-based technique is useful for better characterization of the AE source [ 145 , 146 , 147 ]. AE parameter analysis of hits or events, signal strength, and energy demonstrate that AE is readily applicable to the detection of corrosion in steel reinforcement, in order to identify the corrosion process, i.e ., initiation of cracks and propagation of cracks, and to locate the early stages of corrosion [ 148 , 149 , 150 , 151 , 152 , 153 , 154 , 155 , 156 , 157 ]. The AE sources are also classified in terms of RA value and average frequency to classify the type of failure and the b -value or Ib -value of AE amplitude distribution for assessing the damage severity [ 151 , 153 , 158 , 159 ].…”

“…Many researchers have considered AE hits to be one of the AE parameters used to study the onset of corrosion and the nucleation of crack in RC structures [ 152 , 153 , 154 , 155 ]. Yoon et al .…”

“…This trend could provide important information for estimating the degree of corrosion. Ohtsu and Tomoda [ 155 , 156 ] investigated AE hits of RC specimens in sodium chloride (NaCl) concentration. Corresponding to two high AE activities, two periods of onset of corrosion and nucleation of cracks were observed.…”

“…[ 153 , 154 ] showed cumulative AE hits and number of AE events in the corrosion process in a cyclic wet–dry test. The generating process of AE hits observed is classified into two stages, which refer to the process of corrosion loss of steel reinforcement due to chloride immersion as observed by Melcher and Li [ 160 ], and previously by Ohtsu and Tomoda [ 155 , 156 ]. Stage 1 (onset of corrosion) corresponds to Phases 1 and 2 and Stage 2 (nucleation of crack) corresponds to Phases 3 and 4.…”

Monitoring fracture of steel corroded reinforced concrete members under flexure by acoustic emission technique

“…The study illustrated the sensitivity of the AE to the ongoing deterioration process and explores its use as a corrosion damage monitoring technique. In some later studies, AE parameters such as accumulated hits, signal strength and energy were successfully used to identify and characterize the process of steel corrosion in RC structures [11,[16][17][18][19]. The AE sources were also classified in terms of RA value and average frequency (AF) to distinguish the type of failure.…”