93 / 2022-04-19 19:39:16

Flexural behaviour of seawater sea-sand coral aggregate concrete beams reinforced with FRP bars

Fibre-reinforced polymer,seawater sea-sand coral aggregate concrete,reinforced concrete beam,flexural behaviour,experiments

The use of locally available raw materials, such as seawater, sea sand, and coral reefs, for construction on remote islands saves transportation costs and guarantees the construction period. These raw materials contain high amounts of corrosive substances such as chloride ions, which increases the corrosion risk of steel reinforcement. The corrosion problem can be addressed by combining chloride ion-carrying raw materials with non-corrosive fibre-reinforced polymer (FRP) reinforcement. In contrast to natural aggregate concrete (NAC), coral aggregate concrete (CAC) is rather brittle in compression, and the applicability of the design formula of FRP-reinforced NAC members to FRP-reinforced CAC members is questionable. This study investigated the flexural behaviours of FRP-reinforced seawater sea-sand CAC beams, where all the raw materials for concrete were collected directly from local islands. First, a group of beams was loaded under four-point bending to evaluate the influence of concrete type and reinforcement ratio on the flexural behaviour of the beams. It is found that the ultimate moment capacity and ductility of FRP-reinforced CAC beams were lower than those of the corresponding FRP-reinforced NAC beams. Subsequently, flexural theorems were applied to derive a model of equivalent rectangular stress block parameters for FRP-reinforced CAC beams. Finally, the flexural strengths calculated using the proposed model were compared with the measured test results, as well as predictions using existing design codes. The proposed model not only reduces the prediction error of the flexural strengths but is also safer and more conservative compared with existing design codes, which is critical for non-ductile FRP-reinforced concrete beams.