Fiber Reinforcement Concrete
Properties of Fiber Reinforcement Concrete
The properties of fiber-reinforced concrete are as follows.
1. Modulus of Elasticity
Modulus of elasticity increases when the fibre content increases. For each 1 percent increase of fiber content, the modulus of elasticity increases by 3 percent.
2. Compressive Strength
For using 4 percent fibers, flexural strength increases by 2.5 percent.
In respect to plain concrete, Fiber reinforcement concrete is about 40 times tough.
5. Impact Resistance
6. Splitting Tensile Strength
Classification of Fiber Reinforcement Concrete
There are many different types of fiber-reinforced concrete. some of them are as follows.
1. Steel Fiber Concrete
Aspect ratios of steel fibers are 30 to 250. It has high structural strength. The diameter of steel fibers varies from 0.25 to 0.75 mm. Steel fibers control the crack widths tightly and hence improves the durability of the concrete.
2. Glass Fiber Concrete
Glass fibers have a tensile strength of 1020 to 4080 N/mm2. The length of the fibers that are used in this type of fibers are generally 25 mm.
3. Synthetic Fibers
Synthetic Fibers are man-made fibres from textile and petrochemical industries. It has high chemical resistance. The melting point of synthetic fibers is high and the modulus of elasticity is low.
There are different types of synthetic fibers like aramid, carbon, nylon, polyester, etc. Synthetic fibers are used in shotcrete and cladding panels.
4. Natural Fibers
Natural fibers obtain by using local manpower and technology. Examples are jute, coir, bamboo, etc. There may be organic decay in these fibers. It has a high impact strength and low modulus of elasticity.
5. Carbon Fibers
Carbon fibers are carbon atoms and are about 5–10 micrometers in diameter. Carbon fibers have many advantages including high-temperature tolerance, low thermal expansion, high chemical resistance, low weight, high stiffness, high tensile strength, etc.
Carbon fibers are usually combined with other materials to form a composite, such as graphite, to form reinforced carbon composites, which have a very high heat tolerance.
6. Macro Synthetic Fibers
Macro synthetic fibers were developed as an alternative to steel fibers in some applications fibers and are made of by blending of polymers.
Initially, they were identified as an alternative to steel fibers in sprayed concrete, but after researching a lot It showed that they have a great role to play in the construction and design of ground-supported slabs and a variety of range of other applications.
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Discrete Fiber Reinforced Concrete
- Concrete roads may undergo spalling, cracking and concrete is weak in tension and also a little ductile. so to mitigate these problems adding discrete fiber can provide a benefit to concrete pavement.
- Fiber used is polyester fiber and polypropylene fiber and M25 concrete mix are used.
- The fibers are aggregate with an extreme deviation in shape from the rounded smooth aggregate.
- Fibers entangle and interlock around aggregate particles and considered as it reduces the workability, this the mix becomes less prone and more cohesive to segregation.
- The fibers are suitable to reinforce the concrete products from glass, steel, and polymers of organic material.
- Vegetable fibers and asbestos fibers that occur naturally such as jute, also usable for reinforcement.
- Fibers are available in different shapes and sizes. They can be classified into two following categories. First one, those which have a higher modulus of elasticity than a concrete matrix call a hard intrusion. The second one with a lower modulus of elasticity called a soft intrusion.
- The major factors that effects the characteristic features of fibre-reinforced concrete are the percentage of fibers, diameter, and length of fibers, water-cement ratio, etc.
- The extent and location to create under load will depend upon the number and orientation of fibers in the cross-section.
- The fibers restrain the shrinkage and creep movements of the unreinforced matrix.
- However, fibers have found to be such a great effect in controlling the compressive creep than the tensile creep of the unreinforced matrix.
Uses of Fiber Reinforcement Concrete
Uses of Fiber Reinforcement concrete are as follows.
- Fiber-reinforced concrete is applied on the refractory lining, overlays of the airfield, road explosive resistant structures, etc.
- While using Glass fiber, it is used for door frames and doors, pressure piles, park benches, permanent and temporary formwork, and also bus shelters.
- It is used for the fabrication of precast products like a manhole cover, boats, pipes, wall panels, beams, stair cased steps, roof panels, etc.
- Fibers are usually used in concrete for controlling the cracking that occurs due to drying shrinkage and to plastic shrinkage. There are some common types of fibers that produce greater abrasion, impact, and shatter resistance in concrete. They also help to reduce the permeability of concrete and hence reduce the bleeding of water.
Advantages of Fiber Reinforcement Concrete
Advantages of Fiber Reinforcement Concrete are described below.
- Fiber-reinforced concrete used in bridges. It helps to prevent catastrophic failures.
- While using Fiber-reinforced concrete in civil structures, maximum corrosion can be avoided.
- Fiber-reinforced concrete is a better suite to minimize the cavitation damage in structures such as navigational locks, bridges piers, sluice-ways, where high-velocity flows encounter.
- the main advantage of fiber reinforced concrete is the reduction of cracking and shrinkage. Fiber reinforcement concrete can also increase tensile strength, can provide impact resistance, and helps to reduce voids in the concrete.
Disadvantages of Fiber Reinforcement Concrete
Disadvantages of Fiber Reinforcement Concrete are described below.
- Fabrication is the main disadvantage associated with fiber reinforced concrete.
- It is difficult to pose and handle problems at the time of placement as the fibres in concrete make concrete very harsh.
- Sometimes Fibres may get concentrated at many places which are not ideal and thus It results in poor quality concrete.
- Concrete gets harsh due to fibres so it may require a higher water/cement ratio.
- The process of mixing and incorporating fibers into the cement matrix is costlier and labor-intensive than the production of plain cement concrete.
Application of Fiber Reinforcement Concrete
Application of Fiber Reinforcement Concrete are as follows.
- Runway, Pavement, and Aircraft parking: Nowadays fiber reinforcement concrete is widely used in the construction site of runways and aircraft parking. pavements of fiber reinforcement concrete are now in service in mild and severe environments.
- Slope stabilization and tunnel lining: Steel fiber reinforced concrete is used to rock slope stabilization and line underground opening. It helps to eliminate the scaffolding and need for a mesh environment.
- Hydraulic structures and dams: Fiber-reinforced concrete is being used for repairing dams and construction and some other hydraulic structures for providing resistance to severe erosion and cavitation that is caused by the impact of large water-born debris.
- Other applications: There is also some other application of fiber-reinforced concrete that includes oil tanks, concrete repairing, water tanks, machine tool frames, lightning poles, etc.
Benefits of Fiber Reinforcement Concrete
The benefits of fiber reinforcement concrete are as follows.
- Fiber reinforcement concrete has a high potential to reduce CO2.
- It has the capability of increased fire resistance.
- It has the characteristics of improved ductility and load capacity.
- Fiber-reinforced concrete has increased abrasion resistance.
- Frc has a higher shear strength and higher flexural strength.
- It has the characteristics of less cracking as it has early age shrinkage.
- There is better cohesion in the freshly mixed fiber reinforcement concrete.