Carbon Fiber as Construction Material

Construction materials have evolved significantly over the past decades. Due to technological advances, new and resilient materials such as carbon fiber are replacing traditional ones. This innovative material is gaining traction in the construction industry due to its strength, durability, and flexibility to be molded into the desired design and structure. Moreover, as the material has a low density and high strength-to-weight ratio, it is being increasingly used in building cars and aircrafts.

Trends in the construction materials industry indicate the growing preference for the innovative carbon fiber in building materials across applications. Carbon fiber is a polymer made of long, fine strands of carbon atoms attached in a crystal formation. For a given cross-section, this material is five times as strong as steel, much lighter, and twice as stiff.

Manufacturers twist the carbon fiber strands together to weave them into fabric or mold them into varied shapes. This can then be used in myriad applications including construction, bicycle frames, aircraft structures, automotive parts, sports goods, and radar domes.

As per an industry report, the size of the composite market globally is expected to expand at a CAGR of 8.8% to USD112.8 billion in 2025 from USD74 billion in 2020, and carbon fiber would be among the frontrunners in this market.

Carbon Fiber in Construction

Adoption of carbon fiber as a construction material is gaining more acceptance. One of its versions, pultruded carbon fiber (made by drawing resin-coated glass fibers through a heated die) has several characteristics that make it suitable for use in the construction of residential and commercial buildings for the following reasons:

• It is a strong and durable material.
• As the structure is lightweight, it requires less manpower for material handling.
• It is well suited for constructing windows, door systems, exterior trim, decks, columns, fences, and pergolas.
• Fatigue resistance and flexibility properties make it more crack-resistant than traditional materials such as steel and concrete, especially when exposed to repeated load-bearing weight.
• It has greater compression strength and can withstand higher pressure.
• Due to its higher resistance to humidity, rain, radiation, and chemicals, structures coated with carbon fiber work efficiently under all environmental conditions.

Applications of Carbon Fiber in Construction Industry

The favorable properties of carbon fiber have led to its widespread use in the construction industry. Typical applications include:

• Precast Concrete Construction: Traditionally, steel mesh reinforcement is used in the outer and inner sections of precast concrete structures. These steel elements are increasingly being substituted with carbon fiber sheets and grids.
  A welded steel grid, commonly used in construction of concrete slabs, can be replaced with a carbon fiber grid to reduce weight and achieve the desired chemical inertness. In the case of sandwich wall panels, carbon fiber can be used as a shear grid or truss.
  In fiber-reinforced concrete, carbon fiber is a suitable replacement for steel as the fiber is made from polyacrylonitrile. Moreover, replacing asbestos with carbon fiber in the preparation of fiber cement improves air quality.

• Reinforcements: Carbon fiber is increasingly used for the external strengthening of structures, e.g., in concrete columns. This eliminates the need for additional anchoring and associated installations, thus saving time and cost.
• Bridge Construction: Carbon fiber is widely employed in the construction of bridge load-bearing structures, carbon fiber cables, decks, and supports.
  Typically, steel is used for reinforcing and pretensioning concrete for bridges. However, a number of applications are using carbon fiber instead as the material is resistant to corrosion, has a longer life span, and is more resistant to temperature variation, moisture, and chemical action.

• Repairing Stressed Structures: Structures made from reinforced or prestressed concrete are generally repaired using fiber-reinforced polymer (FRP) laminates. The FRP laminate is bonded to the structure to be repaired with a resin. This technique improves the shear and flexural capacity of beams and slabs, and also enhances confinement in columns and requires minimal additional weight.

Disadvantages of Carbon Fiber in Construction

Carbon fiber is more expensive than other materials. However, while steel and aluminum are less expensive, they require more workforce for material handling.

Carbon Fiber and Sustainability

Carbon fiber has gained wide-scale acceptability in the construction industry due to its strength, light weight, and cost-effectiveness. However, this has raised concerns over its sustainability.

There are various kinds of carbon fibers, and though they are usually environment friendly (i.e., biodegradable and recyclable), not all high-carbon fibers impact the carbon footprint as the underlying science is rather nuanced.

Lignin-based carbon fiber is normally green as it is a natural resource extracted from plant cell walls. It has a carbon content of 50–71% and possesses all the general characteristics of carbon fiber. This type of fiber is used for low-cost applications and is easily recyclable.

Carbon fiber that is meant to retain its strength and shape is difficult to recycle and non-biodegradable. However, the resins used to bind the fiber are decomposable. The process of recycling the resin is called pyrolysis, where the resin is burnt off the fiber at high temperatures.

Manufacturing carbon fiber is an energy-intensive process, especially for oxidation and carbonization. To increase overall sustainability and reduce the carbon footprint, many manufacturers use green energy (wind/solar). Undoubtedly, as with any material involving a long and energy-intense manufacturing process, producing carbon fiber potentially endangers the environment. However, this impact can be mitigated by responsible manufacturing through the use of green energy to power the process.

Case Studies of Carbon Fiber Usage in Construction

A well-known application of carbon fiber in the construction industry is Apple’s floating carbon-fiber roof that is designed to consume lower energy and be environmentally sustainable.

Another example of a first-of-its-kind application of fiber-reinforced plastic is found on the campus of Dresden University of Technology, Germany. The university’s building, Carbonhaus, is the first in the world to be reinforced using carbon fiber in order to replace more traditional materials such as concrete and steel.

Conclusion

The prospects for large-scale use of carbon fiber in construction hold substantial promise. Carbon fiber aids builders in meeting close tolerance requirements, enables easy and quick installation, and helps reduce maintenance costs. Considering the varied advantages it has to offer, carbon fiber is clearly the material of the future. The pace of its wider adoption in newer applications would mostly depend on the capacity of existing manufacturing facilities. Hence, manufacturers need to commit to scaling up capacity and making efforts to drive its adoption.