Experimental study on the bonding behavior of post-embedded steel bar and brick masonry

Post-embedding of steel bars into mortar joints of unreinforced masonry walls is a widely used strengthening technique in historic masonry construction. Despite its widespread use, limited research is available on the effectiveness of this technique for improving the bonding performance of post-embedded steel bars. In this study, the bond-slip relationship for bars embedded in mortar joints was investigated. The masonry specimens were built using mortar with a strength of 5 MPa, and then reinforced with 5, 10, 15, and 20 MPa mortar and plain steel bars 6 and 8 mm in diameter, and a series of pull-out tests were performed on these specimens. By analyzing the bond strength between the post-embedded steel bars and brick masonry, the bond failure modes, and the bond-slip curves, a typical bond-slip curve and bonding parameters were obtained. The effects of the mortar strength, steel bar diameter, and bond length on the bond strength were discussed, and a mathematical expression for the bond strength between the post-embedded steel bars and brick masonry was presented. In addition, the relationship between the bond strength and the slip distance of the steel bars was obtained, and the interfacial bond fracture energy was analyzed.