Question

FIBER REINFORCED CONCRETE

Explain the use of the following fibers:

a) Steel

b) Glass

c) Natural

d) Polymer

e) Asbestos

f) Carbon

Answer 1

fiber reinforced concrete

the fiber reinforced concrete is composit concrete. which contain a mixture of concrete ,some plastimers and suitable fibers.

the effect of fiber in fiber reinforced concrete

• contol the craking due to plastic shrinkage and drying shrinkage.
• reduce the bleeding of concrete.
• helps to increase the tensile strength of the concrete.
• reduce the air voids and icrease the durability.
• reduce the creep
• some fibers may reduse the strength of the concrete.

factors effecting the properties of the fiber

• volume of the fiber in concrete.
• relative fiber matrix
• orientation of fiber
• workability and compaction during concreting
• size of aggregate.
• mix proportion

types of of the fiber reinforced concrete

1. steel fiber reinforced concrete
2. glass fiber reinforced concrete
3. organic / natural fiber reinforced concrete
4. polypropelene  fiber reinforced concrete
5. asbestos fiber reinforced concrete
6. carbon fiber reinforced concrete

steel fiber reinforced concrete

• the steel fiber ued for this concrete having the diameter 0.25mm to 0.75mm.
• the hooks are provided both ends to increase the bond to the matrix.
• it increas the toughness and durability of concrete.
• iprove the tensile and flexural strength
• it iprove the resistance against corrosion, impact and abaration
• it reduce the cracking in concrete.

glass fiber reinforced concrete

• the glass fibers can be chopped in to various length.
• it is not possible to mix more than 2% by volume of concrete mix.
• the fibers having length 25mm is usually used in concrete mixing.
• it is obtained from molten glass in specific proportions.
• it is made from natural materials so it is not harm to nature.
• it has high bending and pulling resistance.
• low hygroscopy so water used can be reduced.
• it has light wight and low density.
• it has great heat and sound inslation capasity.
• it has resistance to crack.
• applications : formork, swimming pool and sewer lining

organic fiber reinforced concrete

• the organic fibers are cheaply available.
• it is chemically more inert than steel and glass fibers.
• juit, coir and bamboo are examples of organic natural fiber.
• it may undergo organic decay
• it has low modulous of elasticity
• it has high impact strength

polymer/ synthetic fiber reinforced concrete

• the polypropelene fibers are cheapest and easly avalilable.
• it has high melting ponts and chemical resistance.
• the dimension used in cncrete is 0.15mm to 15mm.
• low maintanace cost
• increse the precast speed of production
• it is environmental friendly concrete.
• poor theral resistance
• sensitive to sunlight
• low modulus of elastisity
• poor bond matrix
• it is a type of nylon, polythene , polyster and polypropelene etc.
• appliction in cladding panel and shotcrete.

asbestos fiber reinforced concrete

• asbestose is a natuarally available in expensive fiber.
• it has high thermal, mechanical and chemical resistance.
• it has low impact strength due to short length.
• it has high tensile and flexral strength.
• it is used by mixing with OPC.

carbon fiber reinforced concrete

• the carbon fibers are high expensive .
• it has modulus of elasticity and flexural strength.
• it has high strength and stiffnes than steel.
• they may be easly damaged so, it is treated by resign coating before using in concrete.

applications of fiber reinfoeced concrete.

1. road pavements and runway
2. tunnel lining and soil stabilization
3. hydraulic structure
4. thin shell, pipe and manhole
5. precast concrete.