Application of carbon fiber composite material (CFRP) in the field of building materials

Carbon fiber is a fiber material composed of graphite with a carbon content higher than 90%. Prepared by reaction process. During the carbonization process, the carbon fiber is pre-stretched along the axial direction, so the graphite crystallites have a preferred orientation, endowing the carbon fiber with the characteristics of high strength and high modulus. In addition, carbon fiber also has excellent properties such as low density, ultra-high temperature resistance, corrosion resistance, atomic radiation resistance, thermal conductivity, and electrical conductivity, making carbon fiber an important reinforcing fiber in composite materials. Carbon fiber composite materials are formed by combining resin, metal or ceramics as the matrix and carbon fiber as the reinforcement. Through the optimization design of the matrix type, carbon fiber content and distribution, components with excellent comprehensive performance can be prepared for aerospace vehicles such as aircraft, rockets, and satellites. 

With the breakthrough of carbon fiber preparation technology and the reduction of production cost in recent years, carbon fiber composite materials have gradually become a research hotspot in the construction functional materials industry at home and abroad. Compared with traditional materials (steel, concrete, etc.) in the field of building materials, carbon fiber composites have special advantages in terms of corrosion resistance, quality, and mechanical properties. At present, the main applications of carbon fiber composites in the building materials industry include carbon fiber reinforced concrete, carbon fiber reinforced resin composite rods, plates, ropes, etc.) and functional composite materials.

The main characteristics of carbon fiber suitable for building materials

1) Anti-acid and alkali.

2) Corrosion resistance, which is why it is used for corrosion control and repair of reinforced concrete structures.

3) Low thermal conductivity.

4) It has high specific strength, so no heavy construction equipment and support structures are required.

5) The curing time is short. Therefore, the construction time is short, which is conducive to shortening the project duration.

6) Has a high ultimate strain.

7) High fatigue resistance. Therefore, maintenance costs are greatly reduced.

8) CFRP is a poor electrical conductor and non-magnetic

9) Light weight, carbon fiber reinforced plastic prefabricated components can be easily transported. Reduced on-site installation labor costs and capital investment costs.

Application of CFRP in the field of building materials

1 CFRP slat

CFRP materials are widely used in the field of reinforced concrete structure reinforcement because of their advantages such as high strength, light weight, and corrosion resistance. The traditional external CFRP reinforcement technology is widely welcomed by engineering circles because of its simple and convenient process. However, it is difficult for CFRP to give full play to its performance as a high-strength material, and the CFRP concrete section is easy to peel off. In order to give full play to the high-strength performance of CFRP, it is pre-stressed, so that the pre-stressed CFRP technology has been developed and utilized.

On the other hand, in order to solve the problem of easy peeling between CFRP and concrete sections, and to better protect CFRP, surface-embedded CFRP technology has been developed and utilized. This technology embeds CFRP tendons or half strips into prefabricated concrete grooves, and fills them with epoxy resin glue to bond CFRP and concrete, and enhance the bonding ability between the two by expanding the bonding area between CFRP concrete.

2 CFRP bars

Traditional steel materials have good tensile and compressive properties, and are widely used in the reinforcement of building materials. However, under the complex climatic conditions, the mechanical properties of steel bars will be severely reduced due to corrosion, and even cause safety accidents. Carbon fiber reinforced resin has corrosion resistance, light weight, high strength, and low thermal expansion coefficient, so it can replace traditional metal materials for building reinforcement.

The carbon fiber rod is made of multiple strands of continuous carbon fiber and thermosetting resin glued together, and then quickly cured and molded through the backlog drawing of the mold. Carbon fiber composite rods and cement have higher bonding strength compared to raw steel, so they are widely used in offshore buildings, chemical plants, highway guardrails, house foundations, and bridges. At the same time, due to the high strength and high rigidity of carbon fiber, the deflection of the structure prepared by using carbon fiber composite rods is much higher than that of reinforced concrete materials.

Carbon fiber is also conductive, and evenly dispersed into cement-based materials can significantly change its electrical conductivity, reduce resistance, and show a good electrothermal effect when continuously energized, which can be used for road engineering deicing.

3 CFRP cloth/sheet

CFRP wraps are used to repair masonry columns. CFRP wraps for corrosion control and repair of reinforced concrete columns. They are also used in the construction of earthquake resistant structures.

CFRP cloth and sheets have been widely used in the strengthening and strengthening of concrete structures. The high corrosion resistance and high specific strength (ratio of strength to weight) of CFRP materials are two important reasons for the development of this technology. An important application of CFRP to strengthen concrete structures is to use outsourcing CFRP sheets to strengthen concrete columns. CFRP sheets can effectively restrain the lateral deformation of concrete columns to improve their bearing capacity and ductility.

CFRP has excellent physical and mechanical properties. The tensile strength is many times stronger than ordinary steel, and the elastic modulus is never worse than steel. So builders like to use it to strengthen and repair concrete. The advantages of carbon fiber reinforced polymer composites are particularly prominent. The structural strength is enhanced, the structure is not easy to crack, and the toughness is stronger.

In conclusion, as a high-performance, multi-functional advanced composite material, carbon fiber composites can be used as structural building materials and functional building materials. With the breakthrough of production and process technology, the cost of carbon fiber composite materials will be reduced, and there will be a huge demand for carbon fiber composite materials in the construction field. Although carbon fiber composite materials have the characteristics of heavy load, light weight, and high strength, they also have good mechanical and physical properties, which can meet the needs of building structures and conform to the development trend of ecological civilization construction.