The Benefits of Carbon Fibre in Existing Structures

11 March 2022
By Members of Remedial Team

Bill Gates once said: “The advance of technology is based on making it fit in so you don’t really even notice it, so it’s part of every day life”.

We know he was likely referring to computers and AI, and all things electronic, however, the truth of this statement cannot be denied when it comes to construction as well. In fact, it could be strongly argued that advances in building technology should equally fit in with users, and not be obtrusive or negatively impacting.

When you look at improvements in construction technology, there have been leaps and bounds. Everything from thinner concrete slabs, to improved fire suppression systems, to thermal windows, to faster construction methods and so forth. In short, as we evolve, so do our product materials, engineering, and construction skills.


What is carbon fibre?

Carbon fibre (called graphite fibre or carbon graphite, is a type of high-performance fibre available for application in civil engineering) has proven to be one of these materials that have aided the construction and rectification industries. Combined with other materials to form a composite, it has become a go-to in many cases as a lightweight, incredibly strong reinforcement that has a high load-bearing capacity. Characteristics that make it an ideal material for our rectification and enhancement projects.

Carbon fibre offers high versatility: Adaptable for different situations, high tensile strength, impressive chemical resistance, wide temperature tolerance and low thermal expansion. Furthermore, Carbon fibre exhibit high elastic modulus and fatigue strength compared to glass fibres and they are lighter than steel yet offer up to five times the strength.

When it comes to service life, studies show that carbon fibre reinforced polymers carry more potential than agamid and glass fibres as they have high chemical resistance, tolerance to high temperatures and low thermal expansion and corrosion resistance.

Because it can be formed at various densities and moulded into limitless shapes and sizes, it has a wide range of applications. Often it is shaped into tubes, fabric, cloth, and can be crafted into numerous composite parts and pieces. These factors have elevated Carbon fibre as an emerging and popular alternative to steel and aluminium in the construction, avionics, and automobile industries.

Because of its low thermal conductivity, Carbon fibre also provides good cohesion when used with concrete, a beneficial property for high loaded floors and roads. It is graded five times stronger than steel while weighing just one-third of it and has a much higher load-bearing capacity.


Carbon fibre technology in construction

Strengthening is among the uses of Carbon fibre in the construction industry.

Typical applications include the strengthening of structures made of; concrete, steel, timber, masonry, and cast iron; retrofitting to improve the load capacity of old structures like bridges, and improving the shear strength and flexural capacity for structures reinforced with concrete. It is also used as a substitute for steel, in pre-stressing materials and in strengthening cast-iron beams.

For repair of pre-stressed concrete (PC) structures, the technology involves Carbon fibre reinforced polymer (CFRP) laminate bonding. A thin flexible fibre sheet adheres to the concrete surface with a thermos set resin increasing the shear and flexural capacity of slabs, beams and confinement in columns.

In instances of precast concrete, rather than using steel mesh reinforcement, a carbon fibre grid can be used in panel faces to act as a mechanical link to the outer and inner sections of the concrete wall. The number of raw materials used, and overall weight is reduced when this strengthening method is employed.

Precast Concrete Construction

Sheets and grids of Carbon fibre can replace the standard steel mesh reinforcement used in the outer and the inner section of concrete precast wall elements. The process of doing this, ensures the overall weight of the structural unit drastically decreases. On the other hand, it is possible to replace a welded grid in concrete slab construction with a Carbon fibre grid, which also reduces total weight and acquires much-needed chemical protection.

Carbon fibre strengthening of concrete structures

The latest trends in construction, concerning repair and rehabilitation have stressed the need for additional strength to existing structures. Some level of strengthening is required for; structures that have changed use, have a degradation problem or experience a design/construction defect.

For strengthening concrete structures externally, Carbon fibre componentss have also gained more popularity. They can be external reinforcement for columns. This strengthening technique reduces the need for extra anchoring works and installation, a tedious and costly undertaking.

Carbon fibre reinforced polymer is a strong durable material that is applied externally to strengthen concrete structures. This eliminates the need to demolish and replace existing structures such as; concrete beams, suspended slabs and structural columns. This method of structural reinforcing is exceptionally cost-effective where a structure needs to handle increased loads or where the design is insufficient.


Repairing stressed structures

Carbon fibre strips can be used to fortify structures in instances where the structure itself requires a load-bearing capacity upgrade. Think bridges, the underside of a supermarket floor, hospitals etc. In these cases, Carbon fibre reinforcement strips mean upgrades can take place without the need to pull down elements of the structure, yet more strength can be achieved.

The fibre’s properties can filter high-temperature gases as electrodes with high; surface area and corrosion resistance, or as an anti-static part. Resistance to fire can also be improved by casting a thin layer of carbon fibres. They considerably improve the fire resistance properties of polymers or thermoset composites, as they have a thick and compact layer of carbon fibres that effectively reflect heat.


The Benefits of Carbon fibre reinforcement strips

Renowned throughout the concreting industry, Carbon fibre reinforcement strips are ideal for use with construction and retrofit applications, particularly with concrete structures that are ageing, damaged or overloaded. Reinforced carbon rods and carbon fibre reinforced graphite are for high-temperature structural applications.

Carbon fibre reinforcement strips are high performance and strength amplifying products that have advantages over steel due to the strength to mass ratio. Light and easy to install, the strips provide an optimal solution for concrete structures that require extra strengthening.

The system does not increase the dead load to structures, in fact, reinforcement strips increase confinement in columns and increase the shear and flexural capacity of beams and slabs. A structure also experiences less corrosion and may be installed in a moderately brief timeframe.


Carbon fibre wrap

Used on steel, masonry, concrete and timber structures, carbon fibre wrapping, also referred to as carbon fibre strengthening or structural carbon fibre is a composite material, typically comprised of woven carbon fibre strands or formed to solid plates.

Resin-impregnated, carbon fibre wrapping is another innovative structural strengthening system that offers an excellent option to traditional methods. They can be bonded to the exterior of; concrete columns, beams, or slabs to add significant strength. This does not add weight and the load on foundations and other structural members.

Carbon fibre wrapping is not only for repairs but can be used extensively in new construction. It helps increase both structural loads and further provides long-term protection. Due to its flexibility, the material can be “wrapped” around structures that do not qualify for traditional structural strengthening methods, such as beams and columns.

A primary benefit of Carbon fibre-reinforced concrete is the enhanced load-carrying capacity, increased service life and enhanced durability. As the wrapping is watertight, it protects structures from additional moisture and corrosion, an excellent solution for reducing the requirement for maintenance and repair work.

Wraps are quick to install and have negligible visual impact. However, successful installation requires experience, qualified engineering design and skill. In fact, the engineering requirement cannot be understated, as a qualified engineer will determine the optimal way to apply, the length of strips and where to place them. From there, as with all restoration work, the initial step is to have the surface prepared correctly to eliminate any chemicals or dirt. Following that, defects in concrete can be repaired with sharp edges and corners smoothed out to prevent points of stress concentrations.