Investigation on Crack Recovery Behavior of Engineered Cementitious Composite (ECC) Incorporated Memory Alloy Fiber at Low Temperature

Traditional cement-based materials are brittle materials with poor toughness and easy cracking characteristics. The formation of cracks due to drying shrinkage and external load accelerated the destruction of building structures. In order to improve the brittleness of concrete, engineered cementitious composites (ECC), a fiber reinforced cement-based composite with high ductility and features of multiple cracking, was proposed and attracted ful attention. Nickel-Titanium (Ni-Ti) alloy fiber had better crack recovery capabilities compared to steel fiber. Therein, Ni-Ti alloy fiber, activated at low temperature, was applied to endow ECC with the function of crack recovery in a short period. Crack recovery performances were investigated by measuring the crack width, water permeability and acoustic emission analysis. Results showed that the flexural strength, and compressive strength of ECC was enhanced by adding Ni-Ti alloy fiber and specimens displayed features of multiple cracking. Further, the crack width was reduced after 45 heat treatment when incorporated by Ni-Ti alloy fibers. Moreover, shape memory effect of Ni-Ti alloy fibers that activated and recovered at a low heat treatment temperature of 45 was verified.