Guide Test Methods for Fiber-Reinforced Polymer (FRP) Composites for Reinforcing or Strengthening Concrete and Masonry Structures

Description

Conventional concrete and masonry structures are rein-forced with nonprestressed steel, prestressed steel, or both. Recently, composite materials made of fibers embedded in a polymeric resin, also known as fiber-reinforced polymer (FRP) composites, have become an alternative to steel reinforcement. Because FRP materials are nonmetallic and noncorrosive, the problems of steel corrosion are avoided with FRP reinforce-ment. Additionally, FRP materials exhibit several properties, such as high tensile strength, that make them suitable for use as structural reinforcement. FRP materials are supplied as bars for reinforced and prestressing applications and in flat sheets or laminates for use as repair materials.

The mechanical behavior of FRP differs from the behavior of steel reinforcement. FRP materials, which are anisotropic due to the fiber orientation in the bars and laminates, are characterized by high tensile strength only in the direction of the reinforcing fibers. This anisotropic behavior affects the shear strength and dowel action of FRP bars and the bond performance of FRP bars to concrete.FRP composites are available with a wide range of mechan-ical properties, including tensile strengths, bond strengths, and elastic moduli. Generally, FRP composites are not covered by national material standards. Instead, manufacturers of FRP composites provide test data and recommend design values based on these test data.

Therefore, it is difficult to compare test results between product manufacturers. In addition, research has considered the durability of FRP reinforcement in environments containing moisture, high and low tempera-tures, and alkaline environments. Test methods that allow for the comparison of mechanical property retention in a wide range of standard environments are needed so that durable FRP-reinforced structures can be ensured.