Concrete containing cement, water, aggregate and discontinuous or uniformly dispersed or discrete fibers is term as Fiber Reinforced Concrete. It is a composite obtain by adding a single type or a blend of fibers to the conventional concrete mix.
Fibers can be in form of steel fibers, glass fibers, natural fibers, synthetic fibers etc.
Why Fiber Reinforced Concrete are use ?
- Main role of fibers is to bridge the cracks that develop in concrete and increase the ductility of concrete elements.
- There is considerable improvement in the post-cracking behavior of concrete containing fibers due to both plastic shrinkage and drying shrinkage.
- They also reduce the permeability of concrete and thus reduce bleeding of water.
- Some types of fibers produce greater abrasion and shatter resistance to impart load.
Types of Fiber Reinforced Concrete
- Steel Fibers
- Glass Fibers
- Carbon Fibers
- Cellulose Fibers
- Synthetic Fibers
- Polypropylene Fibers
- Nylon Fibers
- Natural Fibers
Steel Fibers ( Fiber Reinforced Concrete )
- Aspect ratios of 30 to 250.
- Diameters vary from 0.25 mm to 0.75 mm.
- High structural strength.
- Reduce crack widths and control the crack width tightly. Thus improving durability.
- Improve impact and abrasion resistance.
- Use in precast and structural applications, highway and airport pavements, refractory and canal linings, industrial flooring, bridge decks etc.
Glass Fibers ( Fiber Reinforced Concrete )
- High tensile strength 1020 to 4080 N/mm2.
- Generally, fibers of length 25mm are use.
- Improvement in impact strength.
- Increase flexural strength, ductile and resistance to thermal shock.
- Use in formwork, swimming pools, ducts and roots, sewer lining etc.
Synthetic Fibers ( Fiber Reinforced Concrete )
- Man made fibers from petrochemicals and textile industries.
- Cheap, abundantly available.
- High chemical resistance.
- High melting point.
- Low modulus elasticity.
- It’s types are acrylic, aramid, carbon, nylon, polyester, polyethylene, polypropylene etc.
- Applications in cladding panels and shotcrete.
Natural Fibers ( Fiber Reinforced Concrete )
- Obtain at low cost and low level of energy using local manpower and technology.
- Jute, coir and bamboo are examples.
- They may undergo organic decay.
- Low modulus of elasticity, high impact strength.
Advantages of Fiber Reinforced Concrete
- High modulus of elasticity the effective long-term reinforcement even in the harden concrete.
- Does not rust nor corrode and requires no minimum cover.
- Ideal aspect ratio which makes them excellent for early-age performance.
- Easily place, Cast, Spray and less labour intensive than placing rebar.
- Greater retain toughness in conventional concrete mixes.
- Higher flexural strength, depending on addition rate.
- Can be make into thin sheets or irregular shapes.
- FRC passes enough plasticity to go under large deformation once the peak load has been reach.
Disadvantage of Fiber Reinforced Concrete
- Greater reduction of workability.
- High cost of materials.
- Generally fibers do not increase the flexural strength of concrete and so cannot replace moment resisting or structural steel reinforcement.
Applications of Fiber Reinforced Concrete
Runway, Aircraft Parking and Pavements.
For the same wheel load FRC slabs could be about one half the thickness of plain concrete slab. FRC pavements offers good resistance even in severe and mild environments.
It can be use in runways, taxiways, aprons, seawalls, dock areas, parking and loading ramps.
Tunnel Lining and slope stabilization.
Steel fiber reinforce concrete are being use to line underground openings and rock slope stabilization. It eliminates the need for mesh reinforcement and scaffolding.
Dams and Hydraulic Structure.
FRC is being use for the construction and repair of dams and other hydraulic structure to provide resistance to cavitation severe erosion cause by the impact of large debris.
Thin Shell, Walls, Pipes, and Manholes.
Fibrous concrete permits the use of thinner flat and curve structural elements. Steel fibrous shotcrete is use in the construction of hemispherical domes.
It is use in animal storage structures, walls, silos, paving, etc.
Precast Concrete and Products.
It is use in architectural panels, tilt-up construction, walls, fencing, septic tanks, grease trap structures, vaults and sculptures.
It is use for exterior and interior floors, slabs and parking areas, roadways, etc.
Warehouse / Industrial
It is use in light to heavy duty loading floors.
It includes application in driveways, sidewalks, pool construction, basements, colored concrete, foundation, drainage, etc.
|Fiber Reinforced Concrete||Normal Reinforced concrete|
|High Durability.||Lower Durability.|
|Protect steel from Corrosion.||Steel potential to corrosion.|
|Lighter materials.||Heavier materials.|
|With the same volume, the strength is greater.||With the same volume, the strength is less.|
|Less workability.||High workability as compare to FRC.|