Investigation of Bonding Behavior of FRP and Steel Bars in Self-Compacting Concrete Structures Using Acoustic Emission Method

Abstract

To extend understanding of the bonding behavior of fiber reinforced polymer (FRP) and steel bars in self-compacting concrete (SCC), an experimental series consisting of 36 direct pull-out tests monitored by acoustic emission (AE) were performed in this paper. The test variables involved rebar type, bar diameter, embedded length, and polypropylene (PP) fiber volume content. For each test, the pull-out force and free end slip were continuously measured and compared with the corresponding AE signals. It was found that the proposed AE method was effective in detecting the debonding process between the FRP/steel bars and the hosting concrete. The AE signal strength exhibited a good correlation with the actual bond stress-slip relationship measured in each specimen. Based on the AE location technique, the invisible non-uniform distribution of bonding stress along the bar was further revealed, the initial location of damage and the debonding process were captured. Additionally, the contribution of bar-to-concrete load-bearing mechanism (chemical adhesion, friction, and mechanical interlocking) to sustain the pull-out force was effectively clarified by studying the collected signals in the frequency domain of AE methods. The experimental results demonstrate that the proposed AE method has potential to detect the debonding damage of FRP/steel bar reinforced SCC structures accurately.

Detecting of the Longitudinal Grouting Quality in Prestressed Curved Tendon Duct Using Piezoceramic Transducers

“…In recent years, piezoceramics transducers have been used to monitor structural health [28][29][30]. Piezoceramic transducers have their superiorities of wide frequency range [31][32][33], low cost [34,35], energy harvesting [36][37][38], and the dual functions as a sensor and an actuator. Among various piezoceramic materials, lead zirconate titanate (PZT) has the strongest piezoelectric effect and can be fabricated in different shapes [39,40].…”

Acoustic Emission Analysis of Corroded Reinforced Concrete Columns under Compressive Loading

“…In 1970, Wells [23] developed an instrument that records the AE signals of deformed concrete. Thanks to the great advance in AE technology over decades, many scholars have used it to study the damage process, deteriorating mechanisms, and failure process of many physical-chemical-thermal-mechanical processes in concrete structures and materials [21,[24][25][26][27]. For instance, Ohtsu summarized the AE characteristics of concrete materials [28,29].…”

Debonding Detection of Reinforced Concrete (RC) Beam with Near-Surface Mounted (NSM) Pre-stressed Carbon Fiber Reinforced Polymer (CFRP) Plates Using Embedded Piezoceramic Smart Aggregates (SAs)

“…Other NDT techniques in civil engineering include acoustic inspection technology [12], ultrasonic method [13], vibro-acoustic technique [14], infrared thermography [15], impact-echo approaches [16], microwave-based methods [17], ground penetrating radar techniques [18], fiber optic sensing [19] and among others. Di et al have demonstrated the bearing mechanism and debonding damage process of FRP and self-compacting concrete by using acoustic inspection technology through experimental research [20]. Hsieh et al discusses the feasibility of using the impact-echo method to assess the debonding flaws at the epoxyconcrete interfaces of near-surface mounted CFRPs [21].…”