Fibre Reinforced Concrete

Fibre Reinforced Concrete


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- Glass Fibres
Fibre Reinforced Concrete- Glass Fibres

Fibre Reinforced Concrete is a composite material consisting of mixtures of cement, mortar or concrete and discontinuous, discrete, uniformly dispersed suitable fibres.

Factors Affecting The Properties Of Fibre Reinforced Concrete

  • 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

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

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

Workability and Compaction of Concrete

Fibres reduce workability

Size of Aggregate

Size of CA is restricted to 10mm


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

Introduction of steel fibres modifies:

1.Tensile strength

2.Compressive strength

3.Flexural strength

4.Shear strength

5.Modulus of Elasticity


7.Impact resistance

8.Strain capacity/Toughness




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