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GLASS FIBERS REINFORCED

CONCRETE

AMJAD ANSARI

INTRODUCTION

• Fiber Reinforced Concrete can be defined as a composite material consisting of mixtures of cement, mortar or concrete and discontinuous, discrete, uniformly dispersed suitable fibers.

• Continuous meshes, woven fabrics and long wires or rods are not considered to be discrete fibres

EFFECT OF FIBERS IN CONCRETE• They control plastic shrinkage cracking and drying shrinkage cracking.

• They also lower the permeability of concrete and thus reduce bleeding of water.

• If the modulus of elasticity of the fiber is higher than the matrix (concrete or mortar binder), they help to carry the load by increasing the tensile strength of the material.

• Some fibers reduce the strength of concrete.

NECESSITY• It reduce the air voids and water voids the inherent porosity of gel.

• It increases the durability of the concrete.• Fibers such as graphite and glass have excellent resistance to creep.

• The addition of small, closely spaced and uniformly dispersed fibers to concrete would act as crack arrester and would substantially improve its static and dynamic properties.

FACTORS EFFECTING PROPERTIES OF FRC

• Relative fiber matrix.• Volume of fiber.• Aspect ratio of fiber.• Orientation of fiber.• Workability and compaction of concrete.• Size of coarse aggregate.• Mixing.

GLASS FIBER REINFORCED CONCRETE

• GFRC is actually cement mortar with countless strands of embedded glass fiber.

• GFRC has a dramatically reduced ballistic debris profile.

• Fibers are the principal load-carrying members

TYPES OF GLASS FIBERS

• A-glass (close to normal glass).• C-glass (resist chemical attacks).• E-glass (insulation to electricity).• AE-glass (alkali resistance).• S-glass (high strength fiber)

PROPERTIES OF GLASS FIBER

• A high tensile strength (1700 N/mm^2) ▪ High modulus.

• Impact Resistance.• Shear strength.• Water resistant.• Thermal conductivity.

PROPERTIES OF GLASS FIBER (COTD.)

• Low thermal expansion.• Less creep with increase in time.• Light weight and Low density.• Resistance to corrosion and Fire endurance.

• Resistance to cracks in concrete

CASTING OF GFRC

• Spray-Up (very strong GFRC due to the high fiber load and long fiber length).

• Premix (less strength than spray-up).• Hybrid Spray-up GFRC.

APPLICATIONS

• Exterior Ornamentation.

• Interior Details.

APPLICATIONS

• Landscape Furnishings.

• Architectural projects.

• Airfields and Runways.

• In Rocket launch pads.

•Tunnel Lining and Slope Stabilization

glass fibre reinforced concrete (gfrc) are being used to line underground openings and rock slope stabilization eliminates the need for mesh reinforcement and scaffolding.

Tunnel lining using (GFRC)

•Thin Shell, Walls, Pipes, and Manhole

• Fibrous concrete permits the use of thinner flat and curved structural elements. Steel fibrous shortcrete is used in the tunnel.• Construction of hemispherical domes using the inflated membrane process. • Glass fibre reinforced cement or concrete (GFRC), by the spray-up process, have been used to construct wall panels. Steel and glass fibres addition in concrete pipes .

•Other Applications

These include machine tool frames, lighting poles, water and oil tanks and concrete repairs.

•Dams and Hydraulic Structure

FRC is being used for the construction and repair of dams and other hydraulic structures to provide resistance to cavitationand severe erosion caused by the Impact of large Waterboro debris.

AIM AND OBJECTIVES OF STUDY• Study the mix design aspects of the GRC.• Understand the various applications involving GRC.• Compare GRC with Normal concrete.• Perform laboratory tests that are related to compressive,

tensile and flexure by use of glass fibre in the concrete pour.

AIM AND OBJECTIVES OF STUDY• The proposed of study aims at analysing the characteristics of

glass fiber reinforced concrete.• Use a glass fiber reinforced concrete with ordinary Portland

cement and decrease the maximum use of ordinary Portland cement.

• As a new construction material (gfrc), we can achieve maximum benefits and different properties of glass fiber reinforced concrete.

• We also compare GFRC, with other cladding materials in different section like quality , cost , properties , benefits etc.

Tests on cement and aggregate

Fineness of Cement•The degree of fineness of cement is a measure of the mean size of the grains in cement.•The rate of hydration and hydrolysis, and consequent development of strength in cement mortar depends upon the fineness of cement. •To have same rate of hardening in different brands of cement, the fineness has been standardized. The finer cement has quicker action with water and gains early strength though its ultimate strength remains unaffected.

Fineness of cement = Mass of residue in grams X 100Mass

•Result : Calculation of Fineness

•Residue of cement is 5 percent.

Mass of cement taken on IS Sieve 100 gMass of residue after sieving 5 g

Specific Gravity of Cement•Specific gravity is normally defined as the ratio between the mass of a given volume of material and mass of an equal volume of water. •One of the methods of determining the specific gravity of cement is by the use of a liquid such as water-free kerosene which does not react with cement. •A specific gravity bottle may be employed or a standard pycnometer may be used.

•Result : Calculation for specific gravity

•Specific gravity of cement, S= W5 (W3 – W1) = 3.09 (W5 + W3 – W4) (W2 – W1)

Mass of empty pycnometer W1 680 g

Mass of pycnometer + water W2 1520 g

Mass of pycnometer + kerosene W3 1340 gMass of pycnometer + cement + kerosene W4 1377.3 g

Mass of cement W5 50 g

Standard Consistency and Setting Time

•Standard Consistency:• Consistency is relative mobility or ability of a freshly mixed concrete to flow.• The object of conducting this test is to find out the amount of water to be

added to the cement to get a paste of normal consistency.

•Mass of cement taken for one mould = 400 gm.

Water Added (ml)

Value of P (%)

Penetration (mm)

100 25 10105 30 22110 35 29115 40 35

• Setting Time:

The Initial Setting Time may be defined as the time at which the matrix is looses it plasticity.The Final Setting Time is a stage when the matrix becomes the hard mass.

The concrete is set to be finally set when it has obtained sufficient strength and hardness.

Mass of cement taken = 400 gm. Mass of water taken = 0.85 P x 400 gm. = 0.85(0.4) x 400

= 128 mlResult : - Standard consistency of cement = 40 per cent.- Initial setting time of cement = 200 minutes.- Final setting time of cement = 395 minutes.

Compressive Strength

•For Ordinary Portland Cement, the compressive strength at 3 and 7 days curing shall not be less than 16MPa and 22MPa respectively.

•Result : Calculation of Compressive Strength of Cement

•Average value = 22.10 N/mm2

S.No.

Load(KN)

Strength(N/mm2)

1

221

22.45

2

225

22.00

3

227

21.87

Specific Gravity and Water Absorption of Fine Aggregates

•The Specific Gravity of an aggregate is defined as the ratio of the mass of a given volume of sample to the mass of an equal volume of water at the same temperature.• The specific gravity of fine aggregates is generally required for

calculations in connection with concrete mix design, for determination of moisture content and for the calculations of volume yield of concrete.

• Result : Calculation of Specific Gravity and Water Absorption

Specific Gravity, G = W2 = 2.45 W2 – (W3 – W1)

Water Absorption = W4 – W5 x 100 = 1.37 % W5

Mass of empty dry flask W 680 gMass of flask + water W1 1533 g

Mass of saturated surface dry sample

W2 500 g

Mass of flask + sample + water

W3 1829 g

Mass of air dried aggregates W4 147 gMass of oven dried aggregates W5 145 g

Specific Gravity and Water Absorption of Coarse Aggregates

•Calculation of specific gravity and water absorption

•Specific Gravity, G = W1 W1–(W3 – W2) 3000 = 2.50

3000 – (2000 – 200)• Water Absorption = W5 – W6 x 100

W5 = 154 – 149 x 100 = 3.24 % 154

Mass of saturated surface dry sample W1 3000 gMass of bucket suspended in water W2 200 g

Mass of material + bucket suspended in water

W3 2000 g

Mass of aggregates taken before drying

W4 150 g

Mass of aggregates taken before drying + water

W5 154 g

Mass of oven dried aggregates W6 149 g

Tests Conducted on GFRC • Compressive strength test on GFRC.

Pictures related to project work

• Flexural strength test on GFRC

CONCRETE MIX DESIGN M40 GRADE CONCRETE

Grade Designation = M-40Type of cement = O.P.C-43 gradeBrand of cement = AmbujaAdmixture = Superplasticizer (HRWR)Fine Aggregate = Zone-IISp. GravityCement = 3.09Fine Aggregate = 2.45Coarse Aggregate (10mm) = 2.5Minimum Cement =400 kg / m3

Maximum water cement ratio = 0.40Concrete Mix Design Calculation: –1. Target Mean Strength = 40 + ( 5 X 1.65 ) = 48.25 Mpa2. Selection of water cement ratio:water cement ratio = 0.40 (selected from IS 456-2000)3. Calculation of water content:Approximate water content for 10mm max. Size of aggregate = 208 kg /m3 (from Table No. 5 , IS : 10262 ). As plasticizer is proposed we can reduce water content by 20%.Now water content = 208 - 41.6 = 167 kg /m3

4. Calculation of cement content:Water cement ratio = 0.40

Water content per m3 of concrete = 167 kgCement content = 167/0.40 = 418 kg / m3 (minimum cement content 400 kg /m3 )Hence O.K.

Total cementitious material content = 418 * 1.10 = 459.8 = 460 kg/m3 (10% increment due to early setting)

Water content = 460*0.4 = 184 kg/m3

Silica fume@20% = 460 * 0.20 = 92 kg/m3

Cement (opc) = 460 – 92= 368 kg/m3 ( saving of cement = 460-368 = 92 kg/m3)

5. Calculation of Sand & Coarse Aggregate Quantities:Volume of concrete = 1 m3

Volume of cement = 368 / ( 3.09 X 1000 ) = 0.119 m3

Volume of water = 184 / ( 1 X 1000 ) = 0.184 m3

Volume of Admixture = 4.60 / (1.145 X 1000 ) = 0.0040 m3

volume of silica fume = 92 / ( 2.2 X1000 ) = 0.041 Total weight of other materials except coarse aggregate = 0.119 + 0.184 + 0.0040 + 0.041 = 0.348 m3

Volume of coarse and fine aggregate = 1 – 0.348 = 0.652 m3

Volume of F.A = 0.652 X 0.41 = 0.267 m3 (Assuming 41% by volume of total aggregate )

Volume of C.A. = 0.652 – 0.268 = 0.384 m3

Therefore weight of F.A. = 0.267 X 2.45 X 1000 = 654.15 kg/ m3

Therefore weight of C.A. = 0.384 X 2.50 X 1000 = 960 kg/ m3

Admixture = 1 % by weight of cement = 3.68 kg/m3

Glass fiber = 0.03 % by volume of concrete.

Cement :Water: F.A : C.A : SF : SP = 1 : 0.4 : 1.7 : 2.6 : 0.25 : 0.012

Compressive and Flexural Strength Test Result

Compressive strength of M20 concrete:1. Normal Concrete

2. Gfr concrete

S.no specimen Curing time Compressive strength

1 Cube 1 7 days 13 Mpa

2 Cube 2 14 days 17.77 Mpa

3 Cube 3 28 days 20.44 Mpa

s.No Specimen Curing time Compressive strength

1 Cube 1 7 days 16.882 Cube 2 14 days 22.663 Cube 3 28 days 27.11

Variation of compressive strength of M20 concrete

Fig 12 Variation of compressive strength of M20 concrete

7 DAYS 14 DAYS 28 DAYS0

5

10

15

20

25

30

Without glassfiberwith glassfiber

Flexural strength of M20 concrete :

1. Normal concrete

2. gfrc

s.No specimen Curing time Flexural strength

1 Beam 1 14 days 2.692 Beam 2 28 days 3.84

s.No Specimen Curing time Flexural strength


Flexural strength of M20 Concrete beam

14 days 28 days0

1

2

3

4

5

6

7

8

9

with glass fiberwithout glass fiber

Flexural strength of M20 concrete beam

Compressive strength of M40 concrete1. M40 Plain concrete:

2. Gfr concrete


1 Cube 1 7 days 23.772 Cube 2 14 days 29.553 Cube 3 28 days 33.33


1 Cube 1 7 days 25.772 Cube 2 14 days 33.773 Cube3 28 days 39.12

Compressive strength graph of M40 concrete

7 days 14 days 28 days0

5

10

15

20

25

30

35

40

45

Withoutwith glass fiber

Flexural strength of M40 concreteFlexural strength of M20 concrete :1. Normal concrete

2. gfrc

s.No Specimen Curing Time Flexural strength


s.No Specimen Curing time Flexural strength


Variation of flexural strength of M40 concrete

14 days 28 days0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

without glass fiberwith glass fiber

CONCLUSION

• The efficient utilisation of fibrous concrete involves improved static and dynamic properties like tensile strength, energy absorbing characteristics, Impact strength and fatigue strength. Also provides a isotropic strength properties not common in the conventional concrete. It will, however be wrong to say that fibrous concrete will provide a universal solution to the problems associated with plain concrete. Hence it is not likely to replace the conventional structural concrete in total.

• Superior crack resistance and greater ductility with distinct post cracking behavior are some of the important static properties of GFRC. The enormous increase in impact resistance and fatigue resistance allow the new material to be used in some specified applications where conventional concrete is at a disadvantage.

• A new approach in design and in the utilization of this material, to account for both increase in performance and economics is therefore,needed. www.studymafia.org

REFERENCES

• www.studymafia.org • www.google.com • www.wikipedia.com• http://www.advancedarchitecturalstone.com• IS 10262-2009•IS 456- 2000•I-ISSN097643945

http://www.wikipedia.com/

http://www.advancedarchitecturalstone.com/

THANKYOU!

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