Bond Resistance of L-Shaped Shape Memory Alloy Fibers in Mortar

Abstract

The interfacial bond resistance of short L-shaped shape memory alloy (SMA) fibers embedded in a mortar matrix was investigated by conducting single fiber pullout tests. In addition, straight SMA fibers were also tested for comparison with L-shaped fibers. Martensitic NiTi and NiTiNb alloys were used in the preparation of short SMA fibers. The martensitic NiTi and NiTiNb wires were cold-drawn and then cut into short fibers. During the cold-drawing process, those SMA wires were pre-strained since the initial diameter of the wires decreased whereas the length of wires was elongated. The cold-drawn straight SMA fibers showed enhanced pullout resistance after 10 min heat treatment at 200 degrees C by application of a hot air gun owing to the shape memory effect. The reduced diameter of the SMA fibers after cold drawn was recovered, due to shape memory effect, after the heat treatment. The L-shaped deformation was introduced to increase the interfacial bond resistance.