Feasibility of self - prestressing concrete members 1 using shape

40 Shape memory alloys (SMAs) are a class of smart materials that recover apparent plastic 41 deformation (~6-8% strain) after heating, thus “remembering” the original shape. This 42 shape memory effect (SME) can be exploited for self post-tensioning applications and 43 NiTi-based SMAs are promising as SME is possible at elevated temperatures amenable 44 to practical application compared to conventional NiTi. This study investigates the 45 feasibility of self-post-tensioned (SPT) concrete elements by activating the SME of 46 NiTiNb, a class of wide-hysteresis SMAs, using the heat of hydration of grout. First, the 47 microstructure characterization of the NiTiNb wide-hysteresis shape memory alloys is 48 discussed. Then, the tensile stress-induced martensitic transformations in NiTiNb SMA 49 tendons are studied. Next, the temperature increase due to the heat of hydration of 50 four commercially available grouts is investigated. Pull-out tests are also conducted to 51 investigate the bond between the grout and SMA bar. Results show that the increase in 52 temperature due to hydration heat can provide significant strain recovery during a free 53