Carbon fiber reinforcement technology is a new type of reinforcement technology that has emerged in recent years and is the fastest-growing. Carbon fiber reinforcement technology began in developed countries such as Japan and the United States in the 1980s. my country started late and started using this technology around 1998.

At present, there are many hidden dangers in construction projects, mainly due to the low design load standards at that time. After the use of functions changes, it cannot meet the current needs of people. These construction projects are in urgent need of repair and reinforcement, and reinforcement methods are selected based on the specific conditions of the project, such as large section method, outer steel reinforcement method, and carbon fiber reinforcement method. Among them, carbon fiber reinforcement is a brand-new reinforcement technology that effectively solves the defects in reinforcement methods such as large concrete sections.

The density of carbon fiber is less than that of steel, but its strength is greater than that of steel. In use, the tensile strength of carbon fiber can reach up to 9 times that of steel. This kind of characteristics of high strength, high elasticity and corrosion resistance are well used in construction, and it also has flexibility. The carbon fiber can be processed, even after the surface is reinforced, the unbalanced area can be glued as a whole. In addition to these advantages, carbon fiber is also a lighter material. After pasting, the weight per square meter is less than 1kg and the thickness is less than 1mm, and it will not increase the size and weight of the original structure after reinforcement.

Compared with traditional concrete reinforcement, carbon fiber construction is simple, reduces the utilization rate of space, does not need to strengthen on-site fixed facilities, and the construction quality is higher. During the construction process, the size and thickness of the structure are basically not increased, and the durability is good. The application of this construction reinforcement method can increase the service life of the building, so this material is used in many industries.

In the carbon fiber reinforcement treatment, the application of high-strength or high-elastic continuous carbon fibers can be unidirectionally arranged into bundles. This case is also called carbon fiber sheet. The carbon fiber sheet is pasted using a prepared resin sheet, mainly on the bridge concrete members and the areas that need to be reinforced. After the resin is cured, it forms a new force-bearing composite with the original, and bears the force together. After carbon fiber reinforcement, it can be suitable for a variety of structural types, such as beams, slabs, columns, bridge piers, cylinders and other structures, and the strength of the base concrete is required to be no less than C15.

Relying only on the carbon fiber sheet itself cannot give full play to its strong mechanical properties and good durability, and the various carbon fiber filaments in the carbon fiber sheet cannot work well together. When bearing a lower load, a part of the carbon fiber filaments with a higher stress level first reach the tensile strength and exit the working state early, and each carbon fiber filament gradually breaks until the whole is destroyed.

After using the bonding material, each carbon fiber filament can work together, thereby improving the tensile strength of the carbon fiber sheet. Therefore, the bonding material plays a key role in the reinforcement of the carbon fiber sheet. It not only ensures that the carbon fiber filaments work together, but also ensures that the carbon fiber sheet and the reinforced structure work together, so as to achieve the purpose of reinforcement. The bonding material is generally epoxy resin. Therefore, the performance of epoxy resin is one of the important indicators. The bonding material should have sufficient rigidity and strength to ensure the transmission of shear force between the carbon fiber sheet and the concrete. At the same time, it should have enough toughness to prevent brittle bond failure due to concrete cracking. It should also be adapted to the conditions of the construction site, that is, it can be cured under normal conditions. It has suitable fluidity and viscosity, and the curing shrinkage rate is small.

Carbon fiber reinforcement construction process

The carbon fiber reinforcement construction process is: surface treatment of beam components → substrate treatment → primer coating → scraping and leveling material → coating a layer of impregnating resin → sticking fiber sheet → applying a layer of impregnating resin → maintenance → protective coating.

With the progress of the times, science and technology and the development of my country's transportation industry, some old bridges have gradually been unable to meet the needs of modern transportation development due to disrepair or increased load, as well as the implementation of the national environmental protection and energy saving requirements. Reinforcement has prolonged the service life, so the old bridge repair and reinforcement task goes deep into the whole process of project construction. First of all, before the construction of the project, the management personnel should actively organize the joint review of the construction drawings, and divide and clarify the key links and key issues in the construction.

In addition, the actual responsibilities of the project supervisors in the control of the progress, quality and cost of the bridge construction should also be clarified. And formulate a strict construction safety guarantee system, formulate plans for safe construction specifications and arrangements for safety precautions. Regular technical meetings are held during actual construction to analyze the current construction problems and formulate corresponding solutions.