Characterization of the shear cracking process in epoxy keyed joints using acoustic emission

• DOI: 10.1016/j.istruc.2025.108438
• Publication Date: 2025-02-17T13:12:02Z
• Authors: Hui Li; Yajun Zhou; Ning Zhang; Wei Shi; Junling Chen; Madjid Karimirad
• Keywords: epoxy keyed joints; acoustic emission; shear cracking process; 620; 543

The utilization of epoxied joints for bonding girder segments in precast concrete segmental bridges (PCSB) has been widely implemented. To gain a comprehensive understanding of the shearing performance of epoxied joints, this study conducted direct shear tests on epoxy keyed and epoxy non-keyed joint specimens, monitoring crack propagation using high-speed cameras and acoustic emission technology (AE). Results showed that concrete crack propagation can be categorized into three frequency ranges: 75–125 kHz, 125–175 kHz, and 275–325 kHz. High-frequency AE signals (275–325 kHz) indicate tensile cracking, while lower frequencies suggest shear failure. By analyzing RA (the ratio of rising time to peak amplitude) and AF (the ratio of ring-down counts to duration) of the AE signals, it was found that the peak positions of the histograms of the RA values for monolithic concrete, epoxy keyed, and epoxy non-keyed specimens were 18 ms/V, 30 ms/V, and 54 ms/V, respectively, while the peak positions of the histograms of the AF values were 110 kHz, 106 kHz, and 98 kHz, respectively. Lower RA and higher AF values indicate tensile failure, while the opposite suggests shear failure. These findings help distinguish between shear and tensile cracks in PCSB structures, providing insights into the failure mechanisms of epoxy bonded joints.