Fiber-reinforced polymer (FRP) composite materials, also known as fiber-reinforced plastic, is a two-component composite material widely used in construction and industry. It is a very effective method of structural reinforcement. These reinforcement materials are popular because of their unique properties such as low weight and high strength.

FRP composite reinforcement system is currently one of the latest methods of building renovation, structural reinforcement and protective coating in various industries. At present, it is widely used in the repair, reinforcement and transformation of buildings, other concrete and steel structures and the composite material industry. It consists of two parts: fiber and matrix (Resin).

In fact, the main function of the matrix is to transfer the shear force from the fiber to the adjacent material and to control the local buckling of the fiber during compression. The matrix should also prevent mechanical damage to the fibers. Fiber has high strength and elastic modulus and is the main component of FRP system. The fibers in fiber-reinforced composite materials can be processed in one or two perpendicular directions. FRP resin is mainly used as a bonding medium to bond fibers together. As mentioned earlier, the carrying capacity of fiber materials is an important part of FRP materials. Therefore, it is fully expected that fiber-reinforced plastic fibers have higher flexural strength and elastic modulus. It also has strong resistance to various environmental conditions, and the fiberglass fiber must also be able to resist extension.

FRP system properties

The most prominent and most important performance of FRP materials is its corrosion resistance. In marine structures such as harbor and coastal structures, the best corrosion resistance of FRP composites is the most useful feature of FRP bars. Fiberglass fiber also benefits from very good insulation properties. Generally speaking, these materials are magnetic and electrically neutral, so they can be considered a very good insulation choice. Therefore, it will be very effective to use FRP reinforced concrete in areas sensitive to magnetic waves in hospitals, as well as to use maglev trains, airport bands, and radar centers.

FRP system application

In recent years, the application of FRP composite materials in strengthening, transforming and repairing reinforced concrete structures has increased considerably. The main reason is the need to extend the service life of infrastructure and improve infrastructure throughout the world. The main advantages of fiber reinforced plastics are high corrosion resistance, easy installation at the installation site, and light weight. Another reason for the massive use of FRP materials is the cost reduction of these materials. In the past two decades, the use of FRP composite materials has been considered a luxurious and expensive way to use in ordinary buildings, and now their manufacturing technology advances have pushed the prices of these materials far below. In the past few years, there has been more and more technical knowledge about the use of FRP, including their mechanical behavior and applications. This growing trend proves the method and importance of this new technology. This new technology seeks to expand the demand and attention for strengthening and modifying structures using composite materials, and to improve the technical knowledge of the design and use of these materials.

The key factors for the increasing use of fiber reinforced plastics in structural reinforcement projects can be summarized as follows:

(1) The ever-increasing supply, production and sales of FRP products have led to a decline in FRP prices and increased FRP purchases and sales

(2) In recent years, due to the continuous improvement of FRP materials and resin performance, these new materials have been applied in most renovation projects

(3) The corrosion resistance and high mechanical strength of FRP materials make the reinforcement and anti-corrosion coatings in concrete, steel, bridges, pipelines, reservoirs, petrochemical and industrial facilities two important topics, while also saving time and cost.

(4) Using FRP to strengthen concrete structures is much cheaper than destroying reinforced concrete structural components and traditional reinforcement

(5) The improved production method of FRP makes the product have higher wear resistance and higher technical indicators, while reducing the price of FRP

FRP reinforcement material

There are two general types of FRP materials used for construction, refinement, and transformation of structures. These two types include fabric and laminate. In addition to these two types, i-shaped and u-shaped FRP profiles, box-shaped and corner-shaped are also used to build new structures and repair buildings. The following describes the application of the above-mentioned commonly used materials in the FRP composite reinforcement system.

(1) fabric

High strength, high modulus, uni- and bi-directional carbon or glass fiber fabrics to be used with resins to form fiber reinforced polymers (FRP) used to strengthen structural concrete elements.

(2) laminate

Pultruded carbon fiber reinforced polymer (CFRP) laminate designed for  strengthening concrete, timber and masonry structures

At present, FRP repair, reinforcement and renovation projects are commonly used, and the use of FRP materials can improve the damage and strength of the structure. In the past 20 years, due to the erosion of infrastructure and the need to strengthen the structure to meet strict design requirements, attention has been paid to the construction and repair of structures around the world. On the other hand, the seismic reconstruction of structures, especially in earthquake-prone areas, has become a very important issue. At the same time, fiber-reinforced composite materials as external reinforcement materials have unique mechanical properties, including high strength, light weight, chemical resistance and easy use. On the other hand, these technologies have become particularly attractive due to their rapid implementation and low cost.