Optimizing Superelastic Shape Memory Alloy Fibers (SMAF) for Enhancing Pullout Performance in Engineered Cementitious Composites (ECC)

This experimental study investigates the effect of superelastic shape memory alloy fibers (SMAF) on the pullout performance of Engineered Cementitious Composite (ECC). Various diameters, forms, and surface treatments of SMAF were examined, including Linear shape (LS-SMAF), indented hook shape (HIS-SMAF), and indented shape (IS-SMAF) with diameters of 0.8 and 1.0 mm. sandpaper polishing technique was used for surface treatment. A constant water-to-cement ratio of 0.60 was used to fabricate ECC. Single-fiber pullout tests, monotonic and cyclic, were conducted on ECC mixtures incorporating various polyvinyl alcohol (PVA) content (1.5% to 2%). Scanning Electron Microscope (SEM) analysis was performed to study the internal structure of ECC. Results showed that treated IS-SMAF demonstrated superior pullout performance. Additionally, IHS-SMAF outperformed LS-SMAF, whereas ECC with higher PVA content showed excellent pullout performance. This study concludes the significance of fiber characteristics and ECC mix composition in enhancing single-fiber pullout performance.