Stay-in-Place Permanent Formwork for Concrete Structures Using FRP-Reinforced Ultrahigh-Strength Engineered Cementitious Composites

This study investigates a novel stay-in-place permanent formwork system employing fiber-reinforced polymer (FRP)–reinforced ultrahigh-strength engineered cementitious composites (UHS-ECCs) to enhance the durability and structural performance of concrete structures. The flexural behavior and failure mechanisms of reinforced concrete beams incorporating a 3-mm FRP bar–reinforced, 20-mm-thick UHS-ECC formwork were evaluated through experimental testing, digital image correlation, and theoretical analysis. For comparison, ultrahigh-performance concrete (UHPC) was used as an alternative formwork material. To improve interfacial bonding, the precast formwork was fabricated with rectangular grooves spaced at 50 or…