Introduction, Necessity and applications of Fibre Reinforced Concrete.

1. PRESENTED BY
HARISH.P.PATIL
4BD11CV015
GUIDED BY
Dr.Anila kumar.C.P

2. CONTENTS
 INTRODUCTION
 BENEFITS OF FRC
 TYPES OF FIBRES
 FACTORS AFFECTING THE PROPERTIES OF FRC
 APPLICATIONS
 CURRENT DEVELOPMENTS IN FRC
 CONCLUSION
 REFERENCES

3. INTRODUCTION
 Plain concrete possess a very low tensile strength,
limited ductility and little resistance to cracking.
 These micro-cracks develop even before loading,
particularly due to drying shrinkage or other causes
of volume change.
 Addition of small, uniformly dispersed fibres to
concrete would substantially improve its static and
dynamic properties.

4. WHAT IS FRC?
Fibre reinforced concrete can be defined as a
composite material consisting of mixtures of cement,
mortar or concrete and discontinuous, discrete, uniformly
dispersed suitable fibres.

5. BENIFITS OF FRC
 Main role of fibres is to bridge the cracks that
develop in concrete and increase the ductility of
concrete elements.
 It helps in improvementation of post cracking
behaviour of concrete.
 It helps in imparting more resistance to Impact load.
 It controls plastic shrinkage cracking and drying
shrinkage cracking.

6. TYPES OF FIBRES USED
 Steel fibres
 Polypropylene and Nylon fibres
 Asbestos fibres
 Glass fibres
 Carbon fibres

7. FACTORS AFFECTING FRC
 Relative fibre matrix stiffness
 Volume of fibres
 Aspect ratio of the fibres
 Orientation of fibres

8. RELATIVE FIBRE MATRIX STIFFNESS
 The modulus of elasticity must be much lower than
that of fibre for efficient stress transfer.
 Low modulus fibres such as Nylons and
polypropylene helps to impart greater degree of
toughness and resistance to impact.
 High modulus fibres such as steel, glass and
carbon imparts strength and stiffness to the
composite.

9. VOLUME OF FIBRES
 The strength of composite largely depends on the
quantity of fibres used in it.
 Use of higher percentage of fibre is likely to cause
segregation and harshness of concrete and mortar.

10. ASPECT RATIO OF THE FIBRES
 It is defined as the ratio of length to its diameter
(L/D).
 Increase in the aspect ratio upto 75 increases the
relative strength and toughness, beyond 75 there
will be decrease in the strength and toughness.

11. ORIENTATION OF FIBRES
 In fibre reinforced concrete the fibres are aligned in
the direction of load, in the direction perpendicular
to that of load, and in the third randomly distributed.
 It was observed that the fibres aligned parallel to
the applied load offered more tensile strength and
toughness than randomly distributed or
perpendicular fibres.

12. APPLICATIONS
 Fibre reinforced concrete is increasingly used on
account of the advantages of increased static and
dynamic tensile strength, energy absorbing
characteristics and better fatigue strength.
 Fibre reinforced concrete has been tried on overlays of
air-field, road pavements, industrial floorings, bridge
decks etc.
 The fibre reinforced concrete can also be used for the
fabrication of precast products like pipes, manhole
covers, beams, stair case steps etc.

13. CURRENTS DEVELOPMENTS IN FRC
The following are the three new developments taking
place in FRC,
 High fibre volume micro-fibre systems.
 Slurry infiltrated fibre concrete (SIFCON).
 Compact reinforced composites.

14. CONCLUSION
 Fiber reinforced concrete is one of the oldest methods
for reinforcing concrete.
 Addition of fibre to conventionally reinforced beams
increases the fatigue life and decreases the crack width
under fatigue loading.
 Cost saving of 10 to 30% over conventional concrete
flooring systems.
 Fibre addition improves ductility of concrete and its
post-cracking load-carrying capacity.

15. REFERNCES
 Concrete technology - M S Shetty.
 Concrete technology - A M Neville & J J Brooks.
 Concrete technology - M L Gambhir.
 ACI committee 544-1990. State-of-the-art report on
fibre reinforced concrete. ACI manual of concrete
practice, Part-5, American Concrete Institute,
Detroit, MI 22 pp.
 ACI committee 544, Report 544 ,1R-82, Concr,Int.,
vol 4, No.5,p.11, 1982.