Crack Healing of Concrete Structures Using Hooked Shape Memory Bars

Cracks are the most common damage type in concrete structures. They impact the durability and structural integrity by allowing rebar corrosion. This research advocates an innovative method for quickly healing (closing) cracks by incorporating shape memory alloy (SMA) bars inside the concrete at tensile regions. This method is deemed valuable for time-sensitive situations like emergency repairs after natural disasters. In this study, two specimens with varying cross-sections and SMA distributions are cast and loaded in tension and flexure. The effect of SMA detailing is studied by comparing the use of end hooks against crimp connectors along the bars. A crack opening displacement gauge and strain gauges are used to monitor the crack width and compressive forces, respectively. Results show that activating the SMA once the concrete has cured can develop permanent prestressing forces which delay cracking. Activating the SMA after cracking has occurred can fully close the cracks.