Use of fiber reinforced polymer composites as reinforcing material for concrete

Although the potential of continuous fiber reinforced polymers (FRPs) was recognized more than 50 years ago, bottlenecks such as vulnerability to static fatigue, ultraviolet radiation, alkaline environment, etc., continued to restrict their use as a construction material. Extensive research across the world during approximately the last 25 years has led to a better understanding of properties and behavior of the FRPs under different conditions. Given their lightweight, noncorrosive, and nonmagnetic nature and their high tensile strength, FRP composites are being used as reinforcement in concrete, especially in prestressed concrete construction, anchors for slope stabilization, and use in special structures such as high-speed linear motor railway tracks, MRI units of hospitals, and repair and rehabilitation works. An attempt has been made in this paper to comprehensively put together the various aspects of FRPs, including their structural and durability characteristics, the ongoing research in the areas related to their utilization as a reinforcing material for concrete structures, and the application of FRP sheets in rehabilitation of deteriorated concrete structures. Though issues related to the manufacture of FRP composites and design procedures have not been considered in detail, they have been included for information and completeness. The paper also presents the current thinking on the design and construction procedures using FRP material in conjunction with concrete and provides a brief discussion of some of the documented applications of FRP composites-rods and sheets-as reinforcement in concrete construction. It may also be mentioned that the paper is largely based on the case studies and research work carried out in Japan; appropriate references to related work in other parts of the world are also included, though in principle there is very little difference in the approaches being adopted across the world.