TYPES of fibre. history of fibre reinforced concrete(FRC). what is FRC. Uses. quantity, ratios, strengths, etc.

1. By Sheetal Verma

2. What is a Fiber…?
 Small piece of reinforcing material possessing
certain characteristic properties.
 Can be circular or flat.
 Parameter used to describe fiber – “Aspect
ratio”.
 Aspect ratio is ratio of its length to its diameter.
 Typical aspect ratio for fibers ranges from 30 to
150.

3. What is Fiber Reinforced Concrete
(FRC)?
 Fiber reinforced concrete (FRC) is concrete containing
fibrous material which increases its structural integrity.
 It contains short discrete fibers that are uniformly
distributed and randomly oriented.
 Fibers include steel fibers, glass fibers, synthetic fibers and
natural fibers.
 Within these different fibers that character of fiber
reinforced concrete changes with varying concretes, fiber
materials, geometries, distribution, orientation and
densities.

4. History of FRC…
 The concept of using fibers as reinforcement is not new. Fibers have been
used as reinforcement since ancient times.
 Historically, horsehair was used in mortar and straw in mud bricks.
 In the early 1900s, asbestos fibers were used in concrete, and in the 1950s
the concept of composite materials came into being.
 There was a need to find a replacement for the asbestos used in concrete
and other building materials due to the health risks associated with the
substance were discovered.
 By the 1960s, steel, glass (GFRC), and synthetic fibers such as
polypropylene fibers were used in concrete, and research into new fiber
reinforced concretes continues today.

5. Fibers used…
Although every type of fiber has been tried out in cement and
concrete, not all of them can be effectively and
economically used. Each fiber has some characteristic
properties and limitations.
Fibers used are-
Steel fibers
Polypropylene, nylons
Asbestos, Coir
Glass
Carbon

6. Steel Fiber
Reinforced Concrete…
 Most commonly used fiber.
 Round fiber of diameter 0.25 to 0.75mm.
 Enhances flexural, impact and fatigue strength
of concrete.
 Used for-overlays of roads, airfield pavements,
bridge decks.
 Thin shells and plates have also been
constructed using stell fibers.

7. Polypropylene/Nylon Fiber Reinforced
Concrete…
 Suitable to increase impact strength of concrete.
 Possess high tensile strength but their low modulus
of elasticity and higher elongation do not
contribute to the flexural strength.

8. Asbestos Fiber
Reinforced Concrete…
 Mineral fiber, most successful of all as it can be
mixed with portland cement.
 Tensile strength of asbestos varies between 560
to 980 N/mm2.
 Asbestos cement paste has considerably higher
flexural strength than portland cement paste.
 For unimportant concrete work, organic fibers
like coir, jute and canesplits are also used.

9. Glass Fiber Reinforced Concrete…
 Recent introduction.
 Very high tensile strength 1020 to 4080 N/mm2.
 Alkali resistant glass fiber has been developed.
 Shows comparable improvement in durability to
conventional E-glass fiber.

10. Carbon Fiber Reinforced
Concrete…
 Posses very high tensile strength 2110 to 2815
N/mm2 and Young’s modulus.
 Cement composite consisting of carbon fibers show
very high modulus of elasticity and flexural
strength.
 Used for cladding, panels and shells.

11. Factors affecting properties of
Fiber Reinforced Concrete…
 Transfer of stress between matrix and fiber.
 Type of fiber.
 Fiber geometry.
 Fiber content.
 Orientation and distribution of fibers
 Mixing and compaction technique of concrete.
 Size and shape of aggregates.

12. Relative Fiber Matrix Stiffness
 Modulus of elasticity of matrix must be much lower than
that of fiber for efficient stress transfer.
 Nylon and propylene fiber impart greater degree of
toughness and resistance to impact.
 Steel, glass and carbon impart strength and stiffness to the
composite.
 Interfacial bonds also determine the degree of stress
transfer.
 Bonds can be improved by larger area of contact,
improving frictional properties and degree of gripping and
by treating steel fibers with sodium hydroxide or acetone.

13. Volume Of Fiber
 Strength largely depends upon the quantity of fibers
used.
 Tensile strength and toughness of the composite
linearly increase with increase in volume of fibers.
 Higher percentage of fibers is likely to cause
segregation and harshness of concrete and mortar.

14. Aspect Ratio Of Fiber
 One of the important factor affecting the properties
and behavior of composite.
 Increase in aspect ration upto 75, increase the ultimate
strength of concrete linearly.
 Beyond 75 relative strength and toughness is reduced.

15. Orientation Of Fibers
 One of the major difference in conventional
reinforcement and fiber reinforcement.
 Specimens with 0.5% volume of fiber were tested
and it showed that when fibers were aligned
parallel to the load applied, more tensile strength
toughness was seen as compared to randomly
distributed and perpendicular fibers.

16. Workability and Compaction of
Concrete…
 Use of steel fibers decrease the workability.
 External vibration fails to compact the
concrete.
 Poor workability is also result of non uniform
distribution of fibers.
 Fiber volume at which this situation is reached
depends on the length and diameter of fiber
used.
 Workability and compaction standard can be
improved with help of water reducing
admixture.

17. Size Of Coarse Aggregates
 Maximum size of aggregates should be
restricted to 10 mm.
 Fibers also act as aggregate.
 The interparticle friction and between fibers
and between fibers and aggregates controls the
orientation and distribution of fibers which
affect the properties of composite.
 Friction reducing admixtures and admixtures
improving the cohesiveness can significantly
improve the mix.

18. Mixing
Mixing is important to avoid balling of
aggregates, segregation and to obtain uniform
composite.
Increase in aspect ration, volume percentage,
size and quantity of aggregates intensify the
balling tendencies.
A steel fiber content in excess of 2% by volume
and an aspect ratio of more than 100 are
difficult to mix.
Addition of fibers before addition of water is
important to get uniform dispersion of fibers in
concrete mix.

19. Typical Proportions For FRC…
Ingredients Proportions
Cement
content
325 to 550
kg/m3
W/C Ratio 0.4 to 0.6
Sand/Total
aggregates
50-100%
Max aggregate
size
10 mm
Air content 6-9%
Fiber Percentage
Steel 1% for
78Kg/m3
Glass 1% for
25Kg/m3
Nylon 1% for
11Kg/m3
Fiber Content:

20. Advantages Of FRC Over Conventionally
Reinforced Concrete…
 Increased static and dynamic tensile strength.
 Energy absorbing characteristics and better fatigue
strength.
 Uniform dispersion of fibers throughout the concrete
provides isotropic properties.

21. Applications…
 Overlays of air-fields.
 Road pavements.
 Industrial flooring.
 Bridge decks.
 Canal lining.
 Explosive resistant structure.
 Refractory lining.
 Fabrications of precast products like pipes, boats,
beams, staircase steps, wall panels, roof panels,
manhole covers etc.
 Manufacture of prefabricated formwork moulds of “U”
shape for casting lintels and small beams.

22. Applications…Roadpavement
Bridgedecks
Precastcanallining
Manholecover

23. Applications…
Fire place made out of GFRC
Air field runway

24. Current development in FRC:-
High fibre volume micro-fibre system.
Slurry infiltrated fibre concrete(SIFCON).
Compact reinforced composites.

25. High fibre volume micro-fibre
system:-
Can replace asbestos fibre.
 Improves toughness and impact strength.
 These properties make it attractive for thin
precast products such as roofing sheets ,cladding
panels.
Cement composites are useful for repair &
rehabilitation works.

26. Slurry infiltrated fiber concrete:-
SIFCON was invented by Lankard in 1979.
Steel fibre bed is prepared and cement slurry is
infiltrated.
Micro-fibre contents up to about 20% by volume can
be achieved.
Increase in both flexural load carrying capacity and
toughness.
High compressive strength is achieved.
Used for blast resistant structures & burglar proof safe
vaults.

27. Compact reinforced
composites(CRC):-
Consist of an extremely strong ,dense cement matrix.
Extremely expensive.
Exhibits flexural strength up to 260Mpa &
compressive strength of about 200Mpa.
As strong as structural steel.
Can be molded and fabricated at site.

28.  Concrete is porous due to air voids ,water
voids.
 Impregnation of monomer & subsequent
polymerization is the latest technique
adapted to reduce porosity and improves
strength.

29. Types: -
Polymer impregnated concrete(PIC).
Polymer cement concrete(PCC).
Polymer concrete(PC).
Polymer impregnated & surface coated polymer
concrete.

30. Polymer impregnated concrete:-
 Precast conventional concrete ,cured & dried in
oven.
 Polymerization carried out by using radiation
,application of heat or by chemical initiation.
 Monomers used are methylmethacrylate, styrene,
acrylonitrile ,t-butyl styrene.
 Amount of monomer loading depends on quantity
of water and air that has occupied the total void
space.
 Monomer loading time can be reduced by
application of pressure.

31. Polymer cement concrete:-
 Made by mixing cement ,aggregates ,water &
monomer.
 Monomers used in PCC are polyster-styrene
,epoxystyrene ,furans ,vinylidene chloride.
 A superior PCC made by furfuryl alcohol aniline
hydrochloride in the wet mix is claimed to be specially
dense ,non-shrinking ,high corrosion resistance ,low
permeability & high resistance to vibrations and axial
extension.

32. Polymer concrete:-
 Aggregate bound with a polymer binder.
 Minimizes void volume in the aggregate mass.
 Strength obtained is 140 Mpa with a short curing
period.
 The graded aggregates are prepacked & vibrated in
mould.
 Tend to be brittle & it is reported that dispersion of
fibre reinforcement would improve the toughness &
tensile strength of material.

33. Partially impregnated & surface
coated concrete:-
 Significant increase in strength of original concrete.
 Polymerisation can be done by thermal catalytic
method.
 Depth of monomer penetration depend upon pore
structure of hardened & dry concrete ,duration of
soaking & viscosity of monomer.
 Excellent penetration can be achieved by ponding the
monomer on concrete surface.

34. Properties of PIC:-
Tensile strength:-
Impregnated concrete is observed to be 3.9 times that
of the control specimen using radiation process of
polymerization.
Flexural strength:-
PIC with polymer loading of 5.6% MMA
shows flexural strength 18.8 Mpa as compared to
5.2Mpa of the control specimen.

35. Stress-strain relationship:-
Compressive strength:-
 Has linear stress-strain relationship to failure.
 Very little departure from linearity up to 90% of ultimate
strength.
 No abrupt change at the proportional limit.
 Using MMA as monomer & with polymer loading of 6.4%
,144 Mpa strength is obtained using radiation technique &
130 Mpa using thermal catalytic process.
 Higher strengths are obtained with MMA impregnated
sample than with polyster styrene.

36. Creep:-
Shrinkage:-
 After typical initial movement during load application ,these
concretes expand under sustained compression.
 Creep deformation generally stabilizes after 2-3 months.
 Occurs through two stages i.e. initial drying & through
polymerisation.
 Several times greater than the normal drying shrinkage.
 Shrinkage is less for higher modulus of elasticity.

37. Water absorption:-
Co-efficient of thermal expansion:-
 Maximum reduction of 95% in water absorption has been
observed with concrete containing 5.9% polymer loading.
 PIC has higher co-efficient of thermal expansion than
conventional concrete.
 Radiation polymerised concrete has co-efficient of thermal
expansion of 5.63 *10-6 and styrene impregnated specimens
have shown a value of 5.1*10-6

38. Resistance to abrasion:-
Wear & skid resistance:-
 PIC shows appreciable improvement in resistance to abrasion.
 5.5% MMA impregnated concrete has been found to be 50 to 80%
more resistant to abrasion than the control specimen.
 On actual wear track test ,the treated surfaces show
excellent skid resistance than the unimpregnated
surfaces.
 The wear after 50,000 simulated vehicular passes has been
less than 0.025 cm.

39. Fracture of PIC:-
 Impregnation improves the strength of mortar matrix &
also the strength of paste-aggregate interface by
elimination of cracks.
 Brittle nature of PIC presents a severe design limitation.
 Fracture mode of PIC can be altered by incorporating a
small quantity of fibers in the matrix.
 Fibers serve to inhibit crack propagation through the
mortar by acting as crack arrestors.

40. Applications of PIC:-
Prefabricated structural elements:-
Pre stressed concrete:-
 For solving problems of urban housing storage ,maintaining
quality ,economy & speed ;prefabricated techniques of
construction are used.
 Can be used in high rise building due to easy handling and
erection.
 PIC provides high compressive strength of 100-140 Mpa ,hence
useful for larger spans and heavier loads.
 Low creep properties of PIC make it good material for
prestressed concrete.

41. Marine works:-
Desalination plants:-
 PIC possessing high surface hardness ,very low permeability &
greatly increased resistance to chemical attack ,is a suitable material
for marine works.
 Material used in construction of flash distillation vessels in
desalination of water has to withstand corrosive effects of distilled
water ,brine and vapour at temp. of 143 C.
 It is seen that there is a saving in construction of cost over that of
conventional concrete by the use of PIC.

42. Nuclear power plants:-
Sewage disposal works:-
 Nuclear container vessels are required to withstand high temp. &
provide shield against radiations.
 PIC having high permeability ,durability and strength are thus
used.
 Concrete sewer pipes deteriorate due to attack of effluents.
 Concrete structures are subjected to attack from corrosive
gases in sludge digestion tanks.
 PIC due to its high sulphate and acid resistance is suitable for
such works.

43. Water proofing of structures:-
Industrial applications:-
 Seepage and leakage of water through bathroom slabs has not
been fully overcome by conventional water proofing methods.
 Use of polymer impregnated mortar provides better water
proofing,
 Concrete has been used for floor in tanneries .chemical factories
,dairy farms and in similar situations for withstanding the
chemical attack ,but performance is unsatisfactory.
 PIC provides a permanent solution for durable flooring in such
situations.

44. Impregnation of Ferro cement products:-
 Ferro cement construction techniques are extensively used in
manufacture of boats ,fishing trawlers ,domestic water tanks
,grain storage tanks ,manhole cove ,etc.
 Ferro cement products are generally thin & as such are liable to
corrode.
 Application of polymer impregnated techniques should improve
the functional efficiency of Ferro cement products.

45. Thank you