Flexural behavior of FRP grid reinforced ultra-high-performance concrete composite plates with different types of fibers

• Propose of a FRP grid-reinforced UHPC plate and study of its flexural behavior. • 26 plates with steel, basalt and PE fibers additions are subjected to four-point bending tests. • Up to 200 % enhancement in flexural capacity can be obtained with PE fiber addition. • Increase fiber content for short basalt or PE fibers (<6 mm) has little enhancement in flexural capacity. • Plates with 1 % volume fraction of 12-mm-length PE fibers is the most economical option. Ultra-high performance concrete (UHPC), which has an excellent compressive strength and an extraordinary durability, has become increasingly popular in structural engineering. However, UHPC has an inferior tensile property to its compressive property, and thus appropriate reinforcing material is necessary in UHPC structures. To this end, fiber-reinforced polymer (FRP) grids have been proposed for UHPC plates as reinforcements (the composite plates are referred to as FRP grid-UHPC composite plates). As the steel fibers in UHPC would still suffer from corrosion problems in aggressive environments, non-metallic fibers can be in UHPC so that steel-free FRP grid-UHPC composite plates are developed. A total of 26 plates (600 mm in length × 120 mm in width × 40 mm in thickness) are prepared for three-point bending tests in this study. The effects of the fiber type, fiber content and the fiber length on the flexural behavior of FRP grid-UHPC composite plates are investigated. Additionally, an analysis into the microstructure based on scanning electron microscope (SEM) of the FRP-UHPC composite plates is conducted. Moreover, a simple evaluation between the costs and the flexural capacities of the FRP grid-UHPC composite plates is conducted. It is economical to adopt 12-mm-length polyethylene (PE) fibers with a 1 % volume fraction to manufacture composite plates. Finally, the ultimate flexural capacities of FRP grid-UHPC plates were predicted using the section analysis approach.