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.
FIBRE REINFORCED CONCRETE

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
FIBRE REINFORCED CONCRETE

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
FIBRE REINFORCED CONCRETE

5. 2. Volume Of Fibres
FIBRE REINFORCED CONCRETE

6. 3. Aspect Ratio of the Fibre
Aspect Ratio of a fibre = Length/Diameter
FIBRE REINFORCED CONCRETE

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
FIBRE REINFORCED CONCRETE

8. 5. Workability and Compaction of Concrete
Fibres reduce workability
6. Size of Aggregate
Size of CA is restricted to 10mm
FIBRE REINFORCED CONCRETE

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
FIBRE REINFORCED CONCRETE

10. Types Of Frc’s Steel Fibre Reinforced Concrete (SFRC)
Polypropylene Fibre Reinforced Concrete (PFRC)
Glass Fibre Reinforced Concrete (GFRC)
FIBRE REINFORCED CONCRETE

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
FIBRE REINFORCED CONCRETE

12. FIBRE REINFORCED CONCRETE

13. FIBRE REINFORCED CONCRETE

14. Introduction of steel fibres modifies:
Tensile strength
Compressive strength
Flexural strength
Shear strength
Modulus of Elasticity
Shrinkage
Impact resistance
Strain capacity/Toughness
Durability
Fatigue
FIBRE REINFORCED CONCRETE

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
FIBRE REINFORCED CONCRETE

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
FIBRE REINFORCED CONCRETE

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.
FIBRE REINFORCED CONCRETE

18. Other Fibres Asbestos Fibres Carbon Fibres Organic/Vegetable Fibres
FIBRE REINFORCED CONCRETE

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
FIBRE REINFORCED CONCRETE

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
FIBRE REINFORCED CONCRETE

21. Organic/Vegetable Fibres
Jute, coir and bamboo are examples
They may undergo organic decay
Low modulus of elasticity, high impact strength
FIBRE REINFORCED CONCRETE