We all know that all buildings have their own vitality. Under the influence and action of nature, bridges will inevitably reduce the use of bridges and cause damage to the safety, durability and service life of bridges. Therefore, we need to frequently repair and strengthen bridges. Among various maintenance and reinforcement methods, with the application of new materials and new processes, the carbon fiber cloth method has the characteristics of convenience, speed and remarkable effect, so it is widely used in bridge maintenance and reinforcement. . At the same time, because the price of carbon fiber composite materials is relatively low, the cost of bridge maintenance and reinforcement projects is greatly reduced.
2. Performance characteristics of carbon fiber cloth
Carbon fiber cloth has a series of excellent properties such as high performance strength, low mass density, not easy to deform at high temperature, not easy to be corroded, strong anti-fatigue characteristics, electrical conductivity under slow deformation, heat transfer and small thermal expansion coefficient, etc.
High-strength carbon fiber yarn is worsted into carbon fiber cloth, which is easy to bond in bridge repair and reinforcement. It is light in weight and thin in thickness, and will not increase the self-weight and cross-sectional area of the bridge, ensuring the construction quality of bridge repair and reinforcement projects. Carbon fiber cloth has high flexibility, can be bent freely, is easy to wind and fold, and is easy to shape. It has the most obvious advantages in repairing and strengthening different types of curved surfaces and circles, especially for special-shaped components. If carbon fiber cloth is used in conjunction with structural adhesives, it is more suitable for repairing and strengthening bridges with wooden structures and concrete structures. The bearing capacity, earthquake resistance and service life of bridges are greatly improved.
Carbon fiber cloth is convenient for construction in bridge maintenance and reinforcement projects. No matter what kind of bridge it is, it can be constructed quickly. The bridge cracks are effectively closed, and the concrete strength is greatly increased. The technical operation of carbon fiber cloth is simple, and it is very convenient to calculate the number of layers that the bridge needs to paste.
3. Construction steps of carbon fiber cloth in bridge maintenance and reinforcement
The carbon fiber cloth operation procedures mainly include: construction preparations before the project, careful treatment of the concrete surface, preparation of repair glue for repair and reinforcement, adhesive glue, leveling, surface wiping, glue brushing, carbon fiber cloth, and finally surface protection.

1. The decorative layer laid on the deck of the bridge to be repaired and strengthened will be removed.

2. Surface treatment of concrete beams. First of all, the peeled, loose, honeycombed, corroded concrete on the bridge surface should be removed to expose the structural layer of the bridge, and repair materials should be used to repair and level the surface of the bridge. The bridge cracks should be sealed according to the requirements of the design drawings. The surface of the pasted concrete should also be smoothed, even exposing the new surface of the concrete structure. Concrete surfaces should be thoroughly cleaned and kept dry.

3. The bottom layer should be coated with bonding agent. The special bottom bonding agent is painted on the surface of the treated beam bottom and soaked into the concrete surface, which can increase the bonding force between carbon fiber cloth and concrete.

4. Finely level the surface of the beam bottom. The bottom of the beam is brushed with the bottom bonding agent, and then the unique epoxy putty leveling material is used to level the fine parts of the bottom layer, so that the carbon fiber cloth can be well combined with the concrete

5. Surface protection and coating. After the carbon fiber cloth is pasted, the surface is coated with cement mortar. The color of the repaired and unrepaired parts must be consistent and the structure is beautiful.

6. Carbon fiber paste. The special bonding material is painted on the bottom layer that has been treated. The carbon fiber cloth should be cut first, and then pasted on the concrete surface. After the carbon fiber cloth is pasted, the bonding material is painted on the surface.

Every part and every process of the bridge maintenance and reinforcement project must be strictly operated. The staff must be professionally trained and must hold a certificate. The construction unit has certain work experience and qualification certificates to ensure bridge maintenance and reinforcement. Engineering reliability.

4. Example of repairing and strengthening bridges with carbon fiber cloth
Shuangfeng Bridge, located at the 102-kilometer column of Bai (Baishaguan) Jing (Jingdezhen), was originally a semi-permanent bridge and was transformed into a permanent bridge in 1970. The bridge was then designed to carry cars - class 13, trailers - class 60. Time flies, time develops, and bridges are also diseased. After a comprehensive inspection by bridge technicians, it was found that the bridge mainly had the following defects:
1. There are tiny cracks and serious crystallization in the I-beam spans of some bridges.

2. The concrete at multiple fulcrums of the I-beam is broken.

3. There is a crack in the third main girder of the second span of the bridge.

4. There are longitudinal and transverse cracks in the slightly bent plates of the bridge.

5. There are large cracks in the bridge deck pavement at the junction of the two-hole I-beams on the fulcrums of each bridge pier, and there will be serious seepage whenever it rains. Bridge construction technicians find out the cause of the disease through on-the-spot investigation:

1. The bearing capacity of bridge I-beams is seriously insufficient.

2. There is no diaphragm between the I-beam and the I-beam, and the overall force bearing capacity of the bridge is not strong.

3. When the vehicle load acts on the slightly curved slab of the bridge, the I-beams on both sides of the slightly curved slab of the bridge will move relative to each other, which is equivalent to the horizontal displacement of the arch foot of the entire arch bridge, which will cause a large part of the vault of the arch bridge. The additional curved cabinets, together with the transverse curved cabinets generated by the load of the passing cars, resulted in longitudinal and transverse cracks in the transverse mid-span of multiple micro-bent plates of the arch bridge.

4. The amount of reinforcement in the bridge pavement concrete is seriously insufficient, and it is difficult for the bridge pavement concrete to bear the tensile stress cracking caused by the negative bending moment at the fulcrum of the bridge pier.

5. The protective layer at the end of the I-beam of the bridge is too thick, especially the horseshoe at the bottom of the I-beam is too much, so when the bridge is subjected to external force, it is difficult to withstand the shear force and break or crack
Using carbon fiber cloth to prescribe the right medicine, the bending strength of the I-beam of the bridge is significantly increased. After maintenance and reinforcement, the Shuangfeng Bridge can load cars -20 grades and trailers -100 grades.