Contents

Introduction

Glass Fibre

Effect of Glass Fibers in concrete

Necessity

Factor affecting the properties of GFRC

Comparison of Mix Proportion of FRC and Plain Concrete

Result

Diagram showing pattern of cracking in GFRC

Introduction

Glass Fibre Reinforced Concrete can be define as a

composite material consisting of mixtures of cement

mortar or concrete and discontinuous, discrete,

uniformly dispersed suitable glass fibre.

GFRC is actually cement mortar with countless strands

of embedded glass fibre

In it fibres are principle load carrying members

against tension.

Glass Fibre

Made up from 200-400 individual filaments

Can be chopped into various lengths, or combined to make cloth mat or tape

Not possible to mix more than about 2% (by weight) of fibres of a length of 20 mm by conventional mixing techniques

Glass Fibre

Glass fibre is chemical inorganic fibre, obtained from

molten glass of a specific composition

Glass fibre is made of natural materials, so that its

products are ecologically pure and not harmful to

human health

High bending, pulling and pressure resistance, high

temperature resistance, resistance against chemical

and biological influences, comparatively low density

Effect of fibers in Concrete

They control plastic shrinkage cracking and shrinkage

cracking.

They also lower the permeability of concrete and thus

reduce bleeding of water.

If the modulus of elasticity of the fibre is higher than the

matrix (concrete or mortar binder),they help to carry the

load by increasing the tensile strength of material.

Some fibers reduces the strength of concrete

Necessity

Glass Fibre increases the compressive strength as well

as tensile strength of concrete

It reduces the air void and water void .

It increases the durability of the concrete.

Fires such as glass have excellent resistance to creep.

The addition of small, closely spaced and uniformly

dispersed fibres to concrete would act as crack

arresters and would improve its strength parameters.

Factors effecting properties of GFRC

Relative Fibre matrix

Volume of Fibre

Aspect ratio of fibre

Workability and compaction of concrete

Size of coarse aggregate

Method of mixing

OBSERVATION :As seen from the graph the strength of Glass fibre reinforced concrete at 0.7% by weight of total mix glass fibre has less compressive strength at 7days as compared to normal cubes. This can be accounted to improper mixing due to difficulty in mixing.The graph clearly indicates the strength of glass fibre reinforced concrete at 0.7% of glass fibre of total mix has less strength than the normal cubes after 28 days of curing.

OBSERVATION:After 7 days of curing , the best results were obtained from the mix containing 0.2% glass fibre by weight of total mix. And the minimum compressive strength is obtained at 0.7% glass fibre by weight of total mix.Even at 0.5% the compressive strength obtained is greater than that obtained from the normal cubes.

OBSERVATION: After 28 days of curing , the best results were

obtained from the mix containing 0.2% glass fibre by weight of total mix. And the minimum compressive strength is obtained at 0.7% glass fibre by weight of total mix.

Even at 0.5% the compressive strength obtained is greater than that obtained from the normal cubes after 28 days of curing.

DIGRAM SHOWING PATTERN OF CRACKING IN GFRC :

Conclusion It can be easily observed from the results that glass fiber (0.2%) has

shown fair improvement in the compressive strength of concrete. However in the results the strength of plain concrete is much higher than the fibre with 0.7% by weight which may be due to the presence of comparatively large fibers in small cubes and further this might be due to improper compaction of cubes.

There has been a great improvement in compressive strength of the concrete for almost all the fibers content below 0.7% by weight of total concrete mix used.

There is phenomenal improvement in compressive strength of glass fibre reinforced concrete. Glass fibre 0.2% has shown the highest improvement of 28.85% followed by 0.5% has shown 14.63 % improvement in compressive strength.

It can be concluded from the results that Glass fibre, if mixed in definite proportion then it could provide much better strength.

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