What are the Constituents of Fiber Reinforced Polymer (FRP) Bars?


Fiber-reinforced polymer (FRP) products are being used predominantly by the aerospace industry. However, the compatibility and performance of FRPs in civil engineering projects have demonstrated great potential. The properties of being corrosion-resistant and high in strength make FRP materials an incredible alternative to conventional reinforcement materials. A number of unique characteristics of fiber-reinforced construction materials expand its applicability for a wide range of applications, both for the rehabilitation of existing concrete structures and building new structures. This blog post will discuss the constituents of FRP bars and how constituents determine the quality of final products.

FRP composite materials are usually based on two major components; fibers and polymer matrix. The stiffness and strength of composite materials are controlled by fibers, while the role of matrix is to transfer load and provide protection against environmental elements. Fillers are also used to avoid cracks and the roughness of the surface. Some ingredients like additives and modifiers help enhance the overall properties of fiber-reinforced polymers. Following is a short introduction to reinforcing fibers and resin matrix.


Manufacturers use different types of fibers that offer varying properties, pros, and cons. As mentioned earlier, fibers are responsible for bringing about strength and stiffness. In structural FRP applications, fibers are used in continuous and unidirectional form as fibers provide ultimate performance when they are in a single direction. Three of the commonly used fibers are carbon, glass, and aramid. The selection of fibers depends on a number of factors such as budget constraints, availability, and required performance.

Glass fibers are used for most of the composite applications because they are relatively cost-effective. Some of the forms of glass fibers include R-glass, E-glass, and S-glass. All forms vary in terms of their mechanical properties. Some of the characteristics of fiber glass are;

  • Moderate elastic modulus
  • High tensile strength
  • Electrically and thermally insulating


Matrix plays a significant role in binding FRP reinforcement materials. The primary role of the matrix is to bind and protect fibers from the environment. Matrix has to be thermally and chemically compatible with fibers. In fiber-reinforced polymers, several polymer matrices are used. However, two main types of polymeric matrices are thermosetting and thermoplastic. If we further elaborate thermosetting resins, which is commonly used for FRP composites, we come across three types namely polyester resin, vinylester resin, and epoxy resin. These materials offer chemical resistance and thermal stability. Vinylesters, for instance, are resistant to alkalis and strong chemicals. As compared with polyesters, vinylesters are more effective against moisture absorption and shrinkage. These are the reasons why vinylesters are widely used to manufacture FRP reinforcement bars.

The last four decades have witnessed a significant growth in the use of FRP reinforcement bars in civil engineering projects. Stats suggest that if appropriately designed and fabricated, FRP reinforcement bars can grant concrete structures longer lifetimes without any considerable maintenance costs. TUF-BAR, for instance, is producing GFRP fiberglass bars using quality materials and standard manufacturing process. The quality of constituents and manufacturing process do matter when it comes to producing fiberglass bars that guarantee structural sustainability.