Flexural Behavior of Seawater Sea-Sand Coral Aggregate Concrete Beams Reinforced with FRP Bars

Using locally available raw materials, such as seawater, sea sand, and coral reefs, for construction on remote islands is conducive to saving costs and shortening the construction time. These raw materials contain high amounts of corrosive substances such as chloride ions, which increase the corrosion risk of steel reinforcement. This study investigated the flexural behavior of seawater sea-sand coral aggregate concrete (CAC) beams reinforced with the noncorrosion fiber-reinforced polymer (FRP) bars. Nine beam specimens were loaded under four-point bending to evaluate the influence of concrete type and reinforcement ratio on their flexural behavior. A model of equivalent rectangular stress block parameters was derived, and the accuracy of the model was validated by the test results. It is found that the ultimate moment capacity and deformability of FRP-reinforced CAC beams were lower than those of the corresponding FRP-reinforced natural aggregate concrete beams. The proposed model reduces the prediction error of the flexural strength and is also safer and more conservative than the existing design provisions, which is critical for nonductile FRP-reinforced concrete beams.