An extensive experimental study was performed to apply acoustic emission (AE) monitoring to assess the bond strength of corroded large-scale RC beam specimens. This paper demonstrates the data obtained from AE monitoring of these RC beams, while being exposed to localized, accelerated corrosion procedures at one of the end sides of each beam. Five RC beams were corroded through an electrically accelerated corrosion process to reach 5, 10, 20, and 30% of steel mass loss. The beams were constantly monitored during the accelerated corrosion tests via half-cell potential (HCP) measurements and three attached AE sensors distributed along the span of the beam. During the test, the corrosion and cover crack initiation were monitored and the crack width measurements were attained daily. The results showed that the analysis of AE signal parameters acquired throughout the corrosion period enabled the detection of both corrosion and cover crack onset earlier than HCP readings and prior to any signs of visual cracking, regardless of sensor location. Acoustic emission parameters examined in this paper {cumulative number of hits, cumulative signal strength (CSS), historic index [$H$ ($t$ )], and severity ($S_r$ )} were shown to be highly correlated with the level of corrosion propagation. The study also presents developed damage classification charts interrelating the results of crack growth and mass losses to the average values of $H$ ($t$ ) and $S_r$ . These charts can be used to quantify the level of deterioration of RC structures due to reinforcement corrosion.

This article presents the results of an experimental investigation on the application of acoustic emission technique for monitoring the steel-to-concrete bond integrity of reinforced concrete structures. A series of direct pull-out tests were performed on 54 reinforced concrete unconfined prism samples with variable rebar diameter (10, 20, and 35 mm), embedded length (50, 100, and 200 mm), and concrete cover (20, 30, and 40 mm). The samples were tested under incrementally increasing monotonic loading while being continuously monitored via attached acoustic emission sensors. These sensors were utilized to acquire different acoustic emission signal parameters emitted throughout the tests until failure. Also, an acoustic emission intensity analysis was implemented on acoustic emission signal strength data to quantify the damage resulting from loss of bond in all tested specimens. This analysis employed the signal strength of all recorded acoustic emission hits to develop two additional parameters: historic index ( H ( t)) and severity ( S _r ). The results of bond behavior, mode of failure, and free end slip were compared with the recorded acoustic emission data. The results showed that the cumulative number of hits, cumulative signal strength, H ( t), and S _r had a good correlation with different stages of bond damage from de-bonding/micro-cracking until bond splitting failure and bar slippage, which caused cover cracking or delamination. The analysis of cumulative signal strength and H ( t) curves enabled early identification of two progressive stages of bond degradation (micro-cracking and macro-cracking) and recognized the various modes of failure of the tested specimens. The variations of bar diameter, concrete cover, and embedded length yielded significant impacts on both the bond behavior and acoustic emission activities. The results also presented developed intensity classification charts, based on H ( t) and S _r , to assess the bond integrity and to quantify the bond deterioration (micro-cracking, macro-cracking, and rebar slip) in reinforced concrete structures.

This experimental study exploits acoustic emission (AE) monitoring to assess the bond behavior of corroded bars in reinforced concrete prism samples under pull-out tests. The analysis of AE parameters obtained in this study including amplitude, duration, cumulative number of hits, and signal strength was performed to identify different stages of bond degradation. The results of bond behavior and free end slip were analyzed and compared with the corresponding AE data. An intensity analysis of AE signal strength was also completed to quantify the bond damage using two additional AE parameters: historic index (H (t)) and severity (S_r). The outcomes of AE analysis enabled the detection of early stages of bond deterioration (micro-cracking) as well as identification of the macro-cracking stage prior to the occurrence of bond splitting failure. The results also showed a good correlation between AE cumulative number of hits and AE signal strength parameters with the steel-to-concrete bond degradation because of corrosion. Finally, the results of H (t) and S_r were employed to generate intensity classification charts to characterize the stages of micro- and macro-cracking and range of slip of corroded reinforcement. Copyright © 2016 John Wiley & Sons, Ltd.