Bond-slip behavior of Aluminum Alloy (AA) bars for near-surface mounted (NSM) technique

• Published in: Engineering structures Vol. 322; p. 119064
• Main Authors: Chen, Xu, Xing, Guohua, Luo, Da, Lu, Yongjian, Chang, Zhaoqun, del Rey Castillo, Enrique, Ingham, Jason
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-01-2025
• Subjects: AA bars; Bond-slip; Constitutive model; Experimental test; NSM technique; AA bars; Constitutive model; Experimental test; Bond-slip; NSM technique
• ISSN: 0141-0296
• DOI: 10.1016/j.engstruct.2024.119064

An experimental study consisting of 22 pull-out tests was carried out to investigate the bond-slip performance and load transfer mechanism between near-surface mounted (NSM) Aluminum Alloy (AA) bars and concrete when the AA bars are inserted into pre-cut grooves on the surface of the host structure and bonded with an appropriate bonding agent. The effects of several design parameters were evaluated including bond length, diameter of AA bars, bar surface treatment, and adhesive type. A digital image correlation (DIC) system was used to measure the slips and surface strain and four failure modes were observed in the tests, being concrete splitting failure, epoxy splitting, debonding at the bar-epoxy interface, and AA bar rupture. Results showed that an increase in bond length could make the failure mode more ductile, while AA bars with rough surfaces exhibited a relatively satisfactory bond-slip behavior when a suitable epoxy was used. Finally, the test data from this study were used to examine three bond-slip models based on fiber reinforced polymers (FRP) for the NSM technique. A new bond-slip model considering the influence of the bar external surface was proposed and validated by the test results from both this study and literature.
•The bond behavior and load transfer mechanisms between NSM AA bar and concrete is experimentally investigated.•Four failure modes were revealed: concrete splitting, epoxy splitting, debonding at the bar-epoxy interface, AA bar rupture.•Increasing the bond length increased the pull-out load but decreased the bond strength.•For AA bars, the larger geometric ratio and the rougher surface is, the better bonding performance could develop.•An analytical model considering the effect of bar surface treatments was proposed.