FRP reinforced concrete materials mainly use FRP sheets, FRP mesh materials and FRP tendons.

• According to the reinforcement position, it can be divided into in vitro reinforcement and in vivo reinforcement. In vitro strengthening mainly include external reinforcement and constraint reinforcement. The reinforcement in the body has embedded reinforcement and grid / grid reinforcement.

• According to the material treatment, it is divided into prestressed reinforcement and non prestressed reinforcement methods.

• According to the role of reinforcement, it can be divided into bending reinforcement method, compression reinforcement method, shear reinforcement method and seismic strengthening method.

Either way, it is required to meet the requirements for reinforcement of reinforced structures and give full play to the performance of fiber composites.

External bonded FRP reinforcement method

The external reinforcement method is mainly to repair and reinforce the concrete structure by sticking fiber reinforced composite (mainly fiber fabric sheet and fiber sheet), also called the external fiber composite material method. Mainly with carbon fiber, glass fiber and other composite materials, adhesive on the main part of the structure of the component, to improve the cross section bending, shear and concrete compressive strength, so as to achieve the purpose of strengthening.

The materials used in the external reinforcement method are of light quality, high strength, simple and quick construction, and can be bonded and strengthened for various shapes of structures (surface or turning and paste). It is suitable for reinforcement of flexural and tensile members due to insufficient reinforcement, especially for simply supported beam and barrier free continuous beam slab. There should be reliable anticorrosion and additional anchorage measures for the reinforcement of the fiber composite material with a long design life, and reliable anchorage and joint construction measures for the frame structure reinforcement.

Embedded reinforcement method

The embedded reinforcement method mainly uses FRP tendons and FRP plates to slotted the surface of the reinforced component (concrete protection layer), and fill the FRP bar or the FRP sheet into it, and use the binder to combine the FRP with the component so as to achieve the purpose of shearing and bending.

The embedded reinforcement method is characterized by less workload and shorter installation time.

The FRP material is protected in the concrete because it is embedded in the concrete. It avoids the adverse effects of corrosion, wear and collision, and is especially suitable for the reinforcement of the bridge deck and the negative bending moment area of the continuous beam.It can be applied to high temperature and high humidity reinforcement works which are difficult to construct by external sticking method, and is easy to anchor with adjacent members when installed.

Compared with the FRP external bonding method, the advantages of this method increase the bonding surface area of the concrete and increase the utilization ratio and reinforcement efficiency of FRP.It reduces the workload of surface treatment of concrete components, improves the work efficiency, and is easy to anchor with corresponding components. The epoxy resin can be replaced by cementitious binder by the embedding method, so it can be applied to reinforce the reinforced concrete works in high temperature and high humidity. When used to reinforce the negative bending moment of the member, it is more advantageous than other reinforcement methods.

Prestress FRP reinforcement method

The prestressed reinforcement method is mainly a design and reinforcement method using prestressed CFRP, prestressed FRP strip and prestressed fiber reinforcement. Because the non prestressed reinforcement technology has little improvement on the stiffness of members, it can not effectively restrain the deflection and crack propagation of members. In order to give full play to the strength advantages of fiber composites and draw lessons from the basic principles of prestressed concrete structure technology, the technology of prestressed reinforcement is put forward. At present, the mature technology is the prestressed CFRP reinforced concrete structure technology, the systematic design and construction methods have been practiced in the engineering application, and the reinforcement of the prestressed CFRP Board has also been applied.

Prestressed reinforcement can give full play to the strength of fiber reinforced materials. In the case of Prestressed CFRP reinforcement, the CFRP strengthening technology has the following advantages as compared with that of CFRP.It can make full use of the characteristics of light weight and high strength of carbon fiber cloth, and can improve the cracking load and yield load of members. It can alleviate the stress lag of CFRP, limit the increase of stress of steel bar, delay the crack of the component effectively, restrict the formation and development of the crack, reduce the width and deflection and deformation of the crack, and improve the working performance of the structure remarkably.

Grid / grid reinforcement method

Grid reinforcement is a whole grid of high performance continuous fibers, such as carbon fiber, glass fiber or polyamide fiber, which are dipped in good corrosion resistant resin. In order to improve the bearing capacity and durability of the structure, the anchor bolt is fixed on the surface of the concrete component, and then the polymer cement mortar is sprayed to make it complete with the original concrete.