What is Fiber Reinforced Concrete?
Fiber-reinforced concrete is a type of concrete that consists of cement, aggregates, and a small amount of fibers.
Fibers are used in concrete to reduce permeability, bleeding, and the formation of minor cracks. Additionally, fibers increase concrete’s tensile strength and impact resistance.
The improvement of weakness is determined by several factors, including fiber materials, fiber shape and size, volume, and distribution pattern in the concrete mix.
Different Types of Fiber Reinforced Concrete
Fibers for concrete come in a variety of sizes and shapes. The major factors that affect the properties of fiber-reinforced concrete are the water-cement ratio, the percentage of fibers, and the diameter and length of the fibers. The various types of fiber-reinforced concrete used in construction are listed below.
Steel Fiber Reinforced Concrete
Steel fiber is a type of metal reinforcement. A certain amount of steel fiber in concrete can cause qualitative changes in the physical properties of the concrete. It can significantly improve tenacity, durability, and other qualities like resistance to cracking, impact, fatigue, and bending. This types of fibres are widely used in structures like flooring, housing, precast, bridges, tunneling, heavy-duty pavement, and mining for improving long-term behavior and enhancing strength, toughness, and stress resistance.
Polypropylene Fiber Reinforced (PFR) Concrete
Concrete reinforced with polypropylene fibers is also referred to as “polypropylene” or “PP.” It is a synthetic fiber made from propylene that is employed in a number of different applications. Typically, these fibers are added to concrete to prevent cracking brought on by drying shrinkage and plastic shrinkage. Additionally, they lessen the permeability of concrete, which in turn lessens water bleeding. Polypropylene fiber is non-polar, partially crystalline, and a member of the polyolefin family. Although it is harder and more heat-resistant than polyethylene, it shares many of the same qualities. It is made of a tough, white material that is highly chemically resistant. Polypropylene is created by combining propylene gas with a catalyst, such as titanium chloride. Polypropylene fiber is highly resistant to acids, alkalies, and organic solvents and has good heat insulation properties.
Glass Fiber Reinforced Concrete
Glass fiber-reinforced concrete is a material made up of numerous extremely fine glass fibers. Glass fiber has mechanical properties that are roughly comparable to polymers and carbon fiber. Even though it is not as rigid as carbon fiber, it is significantly less brittle and much cheaper when used in composites. Therefore, glass fibers are used as a reinforcing agent in many polymer products to create glass-reinforced plastic (GRP), also known as “fiberglass,” which is a very strong and relatively lightweight fiber-reinforced polymer (FRP) composite material. This material is much denser than glass wool, contains little to no air or gas, and performs much worse as a thermal insulator.
Polyester fibers are used in fiber-reinforced concrete, which is used in industrial and warehouse floors, pavements and overlays, and precast products. When properly designed, polyester micro- and macro-fibers improve toughness and the ability to deliver structural capacity in concrete, respectively, and provide good resistance to the formation of plastic shrinkage cracks compared to welded wire fabric.
Carbon fibers are fibers with a diameter of 5–10 micrometers and are primarily made of carbon atoms. Carbon fibers have a various benefits, including high stiffness, high tensile strength, low weight, high chemical resistance, high temperature tolerance, and low thermal expansion. Typically, carbon fibers are combined with other materials to form a composite. When carbon fiber is impregnated with a plastic resin and baked, it forms carbon-fiber-reinforced polymer (also known as carbon fiber), which has a very high strength-to-weight ratio and is extremely rigid, though somewhat brittle. Carbon fibers are also mixed with other materials, such as graphite, to create reinforced carbon composites with extremely high heat tolerance.
Natural fiber can be obtained directly from an animal, vegetable, or mineral source and converted into nonwoven fabrics such as felt or paper, or into woven cloth after spinning into yarns. A natural fiber is also defined as an agglomeration of cells with a small diameter in comparison to their length. Despite the fact that fibers are abundant in nature, especially those that are cellulosic, like cotton, wood, grains, and straw. Since many of these fibers are readily available locally and are abundant, it is recommended to use them when making concrete. The concept of adding such fibers to brittle materials to increase their strength and durability is not new; for instance, straw and horsehair are used to make bricks and plaster. Natural fibers are suitable for concrete reinforcement and are widely available in developing countries.
Application of Fiber Reinforced Concrete
Applications of fiber-reinforced concrete depend on how the applicator and builder take advantage of the static and dynamic characteristics of the material. Some of its areas of application are:
- Slope Stabilization
- Tunnel Lining
- Thin Shell
- Aircraft Parking
- Hydraulic Structure
- Elevated decks
- Warehouse floors
Advantages of Fiber Reinforced Concrete
- High tensile strength and resistance to thermal shocks and fatigue stresses.
- Reduced permeability, bleeding, and the formation of microcracks.
- Enhanced toughness.
- High rigidity at the flexure.
- Minimal impact of weathering.
- Reduces deflection.
- Little corrosion.
Disadvantages of Fiber Reinforced Concrete
- Fibers are expensive.
- To prevent lumps from forming and poor mixing, the fibers in concrete should be distributed evenly.
- The coarse aggregate can only be larger than 10 mm.
- Mixing fibers in huge volumes could be time-consuming.
- Skilled labor is needed when using FRC in construction.