Bond behavior between Fe-SMA strips and mortar in masonry joint after resistive heating

Abstract

In recent years, iron-based shape memory alloys (Fe-SMA) have attracted much interest as an innovative prestressing material with the ability to eliminate the need for on-site tensioning and complex anchoring. This unique property offers application potential for using Fe-SMA to effectively strengthen masonry structures, especially in narrow space joint strengthening applications. Here, based on the premise that the Fe-SMA needs heating to generate prestress, the bond characteristics between the Fe-SMA strips and mortar in the masonry joint after resistive heating were investigated. The effects of various factors, such as heating time, strips surface condition, and bond length, on the bond behaviors were analyzed. The results show that under reasonable resistance heating conditions, Fe-SMA did not significantly damage the bonding interface during masonry joint strengthening. After resistive heating at a heating temperature of 200 °C and a heating time of 30 s, the bond strength of the specimens remained high, and it only decreased by 9.38 %∼10.36 % of the bond strength of the unheated specimen. Following the rough surface treatment of Fe-SMA strips, the bonding properties of the Fe-SMA strips were obviously improved before and after resistive heating, and bond energy dissipation was the clearest performance increase to over 5 times the original value. In addition, a prediction model for the bond strength between the Fe-SMA strip and mortar in masonry joint strengthening after resistive heating was proposed and could provide references for subsequent studies.