Fibre reinforced concrete is a composite material made of cement, mortar or concrete with small, closely spaced fibres added to increase tensile strength and crack resistance. The document discusses factors that affect fibre reinforced concrete properties like fibre-matrix stiffness, fibre volume, fibre aspect ratio, fibre orientation, workability, aggregate size and mixing. It also describes different types of fibre reinforced concrete including steel, polypropylene and glass fibre reinforced concrete and their applications in construction.

1. FIBRE REINFORCED
CONCRETE
BUILDING TECHNOLOGY AND MANAGEMENT

2. NEED
 PCC has low tensile strength, limited ductility and
little resistance to cracking
 PCC develops micro-cracks, even before loading
 Addition of small, closely spaced and uniformly
distributed fibres act as crack arresters.
FIBRE REINFORCED CONCRETE is a
composite material consisting of mixtures of
cement, mortar or concrete and discontinuous,
discrete, uniformly dispersed suitable fibres. 2
FIBREREINFORCEDCONCRETE

3. FACTORS AFFECTING THE PROPERTIES OF
FRC
 Relative Fibre Matrix Stiffness
 Volume of Fibres
 Aspect Ratio of the Fibre
 Orientation of Fibres
 Workability and Compaction of Concrete
 Size of Coarse Aggregate
 Mixing
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4. 1. RELATIVE FIBRE MATRIX STIFFNESS
 Modulus of elasticity of matrix must be much
lower than that of fibre. E.g. steel, glass,
carbon
 Fibres with low modulus of elasticity- nylon,
polypropylene
 Interfacial bond between the matrix and the
fibres determine the effectiveness of stress
transfer
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5. 2. VOLUME OF FIBRES
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6. 3. ASPECT RATIO OF THE FIBRE
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Aspect Ratio of a fibre = Length/Diameter

7. 4. ORIENTATION OF FIBRES
The effect of randomness, was tested using
mortar specimens reinforced with 0.5% volume
of fibres, by orienting them:
 parallel to the direction of the load
 perpendicular to the direction of the load
 in random
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8. 5. Workability and Compaction of
Concrete
Fibres reduce workability
6. Size of Aggregate
Size of CA is restricted to 10mm
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9. 7. MIXING
Cement content : 325 to 550 kg/m3
W/C Ratio : 0.4 to 0.6
% of sand to total aggregate : 50 to 100%
Maximum Aggregate Size : 10 mm
Air-content : 6 to 9%
Fibre content : 0.5 to 2.5% by vol of mix
: Steel -1% - 78kg/m3
: Glass -1% - 25 kg/m3
: Nylon -1% - 11 kg/m3
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10. TYPES OF FRC’S
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11. STEEL FIBRE REINFORCED CONCRETE
(SFRC)
 Aspect ratios of 30 to 250
 Diameters vary from 0.25 mm to 0.75 mm
 Hooks are provided at the ends to improve
bond with the matrix
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12. 12
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13. 13
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14. INTRODUCTION OF STEEL FIBRES
MODIFIES:
1. Tensile strength
2. Compressive strength
3. Flexural strength
4. Shear strength
5. Modulus of Elasticity
6. Shrinkage
7. Impact resistance
8. Strain capacity/Toughness
9. Durability
10. Fatigue 14
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15. APPLICATIONS OF SFRC
 Highway and airport pavements
 Refractory linings
 Canal linings
 Industrial floorings and bridge-decks
 Precast applications - wall and roof panels, pipes,
boats, staircase steps & manhole covers
 Structural applications
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16. POLYPROPYLENE FIBRE REINFORCED
CONCRETE (PFRC)
 Cheap, abundantly available
 High chemical resistance
 High melting point
 Low modulus of elasticity
 Applications in cladding panels and shotcrete
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17. GLASS FIBRE REINFORCED CONCRETE
(GFRC)
 High tensile strength, 1020 to 4080 N/mm2
 Lengths of 25mm are used
 Improvement in impact strengths, to the tune of
1500%
 Increased flexural strength, ductility and
resistance to thermal shock
 Used in formwork, swimming pools, ducts and
roofs, sewer lining etc. 17
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18. OTHER FIBRES
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19. ASBESTOS FIBRES
 High thermal, mechanical and chemical
resistance
 Short in length (10 mm)
 Flexural strength is 2 to 4 times that of
unreinforced matrix
 Contains 8-16% of asbestos fibres by volume
 Associated with health hazards, banned in
many countries
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20. CARBON FIBRES
 Material of the future, expensive
 High tensile strengths of 2110 to 2815 N/mm2
 Strength and stiffness superior to that of steel
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21. ORGANIC/VEGETABLE FIBRES
 Jute, coir and bamboo are examples
 They may undergo organic decay
 Low modulus of elasticity, high impact
strength
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