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Int. J. Struct. & Civil Engg. Res. 2013 Komal Chawla and Bharti Tekwani, 2013

STUDIES OF GLASS FIBER REINFORCEDCONCRETE COMPOSITES

Komal Chawla1* and Bharti Tekwani1

1 University College of Engineering Kota, Rajasthan Technical University, Kota, Rajasthan, India.

*Corresponding Author: Komal Chawla, komalc071@gmail.com

ISSN 2319 – 6009 www.ijscer.comVol. 2, No. 3, August 2013

© 2013 IJSCER. All Rights Reserved

Int. J. Struct. & Civil Engg. Res. 2013

Research Paper

INTRODUCTIONAims and Scope

Concrete is the most widely used constructionmaterial has several desirable properties likehigh compressive strength, stiffness anddurability under usual environmental factors.At the same time concrete is brittle and weakin tension. Plain concrete has two deficiencies,low tensile strength and a low strain at fracture.These shortcomings are generally overcome

by reinforcing concrete. Normally reinforcementconsists of continuous deformed steel bars orpre-stressing tendons. The advantage ofreinforcing and pre-stressing technologyutilizing steel reinforcement as high tensilesteel wires have helped in overcoming theincapacity of concrete in tension but theductility magnitude of compressive strength.Fibre Reinforced Concrete (FRC) is aconcrete made primarily of hydraulic cements,aggregates and discrete reinforcing fibres.

Plain concrete possess very low tensile strength, limited ductility and little resistance to cracking.Internal micro cracks are inherently present in concrete and its poor tensile strength is due topropagation of such micro cracks. Fibers when added in certain percentage in the concreteimprove the strain properties well as crack resistance, ductility, as flexure strength and toughness.Mainly the studies and research in fiber reinforced concrete has been devoted to steel fibers. inIn recent times, glass fibers have also become available, which are free from corrosion problemassociated with steel fibers. The present paper outlines the experimental investigation conductson the use of glass fibers with structural concrete. Cem-fill anti crack, high dispersion, alkaliresistance glass fiber of diameter 14 micron, having an aspect ratio 857 was employed inpercentages , varying from 0.33 to1 percentage by weight in concrete and the properties of thisFiber Reinforced Concrete (FRC) like compressive strength, flexure strength, toughness,modulus of elasticity were studied.

Keywords: Cem-fill anti crack glass fibers, Reinforcement, Super plasticizer (B233 nepthalenebased).

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Int. J. Struct. & Civil Engg. Res. 2013 Komal Chawla and Bharti Tekwani, 2013

FRC is a relatively new material. This is acomposite material consisting of a matrixcontaining a random distribution or dispersionof small fibres, either natural or artificial, havinga high tensile strength. Due to the presence ofthese uniformly dispersed fibres, the crackingstrength of concrete is increased and the fibresacting as crack arresters.

Experimental Program

The details of materials used in the presentprogram are as follows.

Cement

Portland pozzolona cement of 43 Gradeavailable in local market has been used in theinvestigation. The cement used has beentested and found to be conforming to the IS1489 specifications. The specific gravity was3.15.

Coarse Aggregate

Crushed angular aggregates from a localsource were used as coarse aggregate.

Fine Aggregate

Zone 3rd sand was used as fine aggregate.The specific gravity was determined and wasfound as 2.74.

Glass Fiber

The glass fibers used are of Cem-FIL Anti-CrackHD with modulus of elasticity 72 GPA, Filamentdiameter 14 microns, specific gravity 2.68,length 12 mm (Properties as obtained throughthe manufacturer are shown on Table 1).

Water

Locally available portable water is used.

Test Specimens

Test specimens consisting of 100×100×100

mm cubes and 100×100×500 mm beamswere cast as shown in Figure 1 and tested asper IS: 516 and 1199.

Figure 1: Test Specimens100×100×500mm

Concrete Mix

The M20 grade is used as design grade forcalculating quantities used in per cubic meterare shown in Table 2. The water cement hasbeen fixed.

Mixing Procedure

Pre Mix GRC

The sand and cement are mixed dry and thenthe water/admixture and polymer (if used) areadded. Generally a two-speed slurry/fibreblender mixer is used. With this type of mixer,the fast speed is designed to create smoothcreamy slurry. This takes about one-twominutes. The mixer is switched to slow speedand fibre in the form of chopped strand (lengthapproximately 13 mm) is added slowly. Thefibre is blended into the mix for approximately1 min. Once the mix is ready, it is poured intothe moulds, which are vibrating using avibrating table.

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Int. J. Struct. & Civil Engg. Res. 2013 Komal Chawla and Bharti Tekwani, 2013

Table 1: Properties of Alkali Resistance Glass Fiber

1. Fiber AR Glass

2. specific gravity 2.68

3. elastic modulus(Gpa) 72

4. tensile strength(Mpa) 1700

5. diameter(micron) 14

6. length(mm) 12

7. number of fibre (million/Kg) 235

Table 2: Mix Proportion of Material

S. No. Material Quantity per m3 in kg

1 cement 33 grade ppc 350

2 fine aggregate 873

3 coarse aggregate (20mm) 444

4 coarse aggregate (10mm) 666

5 Water 140

6 Fiber 0-1% by total weight of mix

7 super plasticizer 5

The product is left into the mould to set andis covered with polythene sheet to preventmoisture loss. The product is demoulded thenext day.

After demoulding the products are curedunder polythene sheets to maintain moistconditions for approximately 2 to 4 days.Alternatively a polymer curing compound canbe used as described for the sprayed process.

After mixing in fully pan mixer, the mix wascast in moulds for each % of fiber sufficient noof cubes (Table 3) and flexure beams(Table 4) were cast for testing at the ages of28 days.

RESULTS AND DISCUSSIONCompressive Strength

The observation from our results shows thatthe increase in compressive strength is up to37% in case of adding 0.33% fiber content incomparison of conventional concrete. Figure3 and Table 5 show the variation incompressive strength by adding fiber.

Flexure Strength

The percentage increase in flexure strength ofglass fiber is observed to be 130% whencompared with ordinary plain concrete.

The percentage increase in flexure strength

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Int. J. Struct. & Civil Engg. Res. 2013 Komal Chawla and Bharti Tekwani, 2013

Table 3: Number of Beam Specimen CastUsing Different Fiber Content and Different Area of Steel

Number Of Beam Specimen Cast Using Different Fiber Content And Different Area Of Steel

% Fiber Diameter in mm 0% 0.33% 0.67% 1% Description

10 4 4 4 4 Under reinforced

12 4 4 4 4 Under reinforced

16 4 4 4 4 Over reinforced

Table 4: Number of Cube Specimen Cast Using Different % of Fiber Content

% fiber 0% 0.33% 0.67% 1%

Number of cube 8 8 8 8

Figure 2: Flexure Testing Arrangement Figure 3: Curve Showing RelationshipBetween % Increase in Compressive

Strength and Fiber Content(at 28 Days age)

Table 5: Variation between Percentage Increase in Compressive Strength

Fiber Content % increase in compressive strength

0% 0%

0.33% 36.67%

1% -4.40%

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Int. J. Struct. & Civil Engg. Res. 2013 Komal Chawla and Bharti Tekwani, 2013

Figure 4: Curve Showing RelationshipBetween % Increase in flexure Strength

and Fiber Content (at 28 Days age)

Table 6: Compressive and Flexure Strength For Different Fiber Content at 28 days

% fiber Compressive strength in N/mm2 Flexure strength in N/mm2

Without reinforcement 10 mm 12 mm 16 mm

0 30 3.19 14.85 17.325 24.075

0.33 41 7.31 11.7 18.225 20.25

0.67 30 7.59 15.7 17.325 17.325

1 28.67 7.07 18.45 18.65 25.5

Table 7: Percentage Increase of Compressive, Flexure Strength of Glass FiberConcrete In Comparison With Ordinary Concrete Mixes at 28 days

% fiber Compressive strength Flexure strength

Without reinforcement 10 mm 12 mm 16 mm

0.33 36.67% 130% 0% 5.19% 0%

0.67 0 138% 5.70% 0% 0%

1 -4.14% 121.63% 24.24% 7.60% 5.91%

of glass fiber reinforced concrete using fibercontent 0.33% and 1.25% steel (12 mmreinforcement bar) is observed to be 150% whencompared with glass fiber concrete (withoutreinforcement). Figure 4 and Table 6show variation of flexure strength with fibercontent (Figure 2 shows the flexure testingarrangement).

Modulus of Elasticity

Young’s modulus is increased by 4.14% for fiberreinforced concrete (0.33% fiber content and 1.25%steel or using 12 mm diameter reinforcement bar)over plain concrete (Table 8).

ToughnessIt can be observed from the Table 9 that thebest performance is given by glass fiberreinforced concrete containing 0.67% fiberand 1.25% steel the highest value of toughnessis 272.41 KNmm (Table 9).

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Int. J. Struct. & Civil Engg. Res. 2013 Komal Chawla and Bharti Tekwani, 2013

Table 8: Observed Modulus of Elasticity

Dia mm Fiber observed modulus of elasticity KNmm2

10 0 11.53

12 0 20.98

16 0 20.12

10 0.33 21.49

12 0.33 21.85

16 0.33 12.85

10 0.67 14.12

12 0.67 20.31

16 0.67 20.31

10 1 8.2

12 1 18.09

16 1 16.46

Table 9: Toughness in KNmm

Fiber%

Diameter in mm 0 0.33 0.67 1

10 11.506 63.99 144.6 19.36

12 59.06 83.98 272.4 75.69

16 116.28 218.6 215.7 72.26

Table 10: Percentage Increase in Toughness

Fiber%

Diameter in mm 0.33 0.67 1

10 456% 1157% 68.26%

12 42.19% 361.20% 28.15%

16 88.06% 85.48% 0%

CONCLUSION1. Addition of glass fiber in reinforced

concrete increases the toughness by

1157% compare with conventionalreinforced concrete. The value of toughnessobserved maximum 272.4 KNmm when

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Int. J. Struct. & Civil Engg. Res. 2013 Komal Chawla and Bharti Tekwani, 2013

using fiber content 0.67% and 1.25% steel(12 mm reinforcement bar) (Tables 9and 10)

2. The modulus of elasticity of glass fiberreinforced concrete is increases 4.14%compared with conventional reinforcedconcrete (Table 8)

3. The percentage increase of compressivestrength of various grades of glass fiberconcrete mixes compared with 28 dayscompressive strength is observed 37%.

4. The percentage increase of flexure strengthof various grades of glass fiber concretemixes compared with 28 days compressivestrength is observed 5.19% (Tables 6and 7).

ACKNOWLEDGMENTWe would like to express our gratitude to oursupervisor, Dr. Praveen Kumar, whoseexpertise, understanding, and patience, addedconsiderably to our graduate experience. weappreciate his vast knowledge and skill inmany areas (e.g., vision, aging, ethics, andinteraction with participants).

We would also like to thank my friends inthe Vision and Aging Lab exchanges ofknowledge, skills, and venting of frustrationduring our B.Tech Graduatation program,which helped enrich the experience. Ouruniversity organized the fund for completing the“glass fiber reinforced concrete” project.

REFERENCES1. h t t p : / / e n . w i k e p e d i a . o r g / w i k i /

Fibre_reinforced_concrete

2. Indian standard Code of Practice forPlain and Reinforced Concrete, IS- 456:2000, 4th Revision, Bureau of IndianStandards, New Delhi.

3. Indian standard Recommendedguidelines for Concrete Mix Design, IS10262: 1982, 5th Reprint 1998, Bureauof Indian Standards, New Delhi.

4. Mallick P K (2007), “Fiber- ReinforcedComposites “, Materials, Manufacturing,and Design.

5. M S Shetty (1987, Concrete TechnologyTheory and Practices, . Chand &Company, New Delhi

6. Perumalsamy N Balaguru and SarendraP Shah (1992), ‘‘Fiber reinforced cementcomposites’’, Mc Graw Hill InternationalEditions.

7. Saint Gobain Vetrotex, Cem – Fil. (2002),“Why Alkaline Resistant Glass Fibers”, InTechnical data sheet”s, www.cemfil.com

8. Siva Kumar A and Santana Manu (2007),“Mechanical Properties of High StrengthConcrete Reinforced with Metallic andNon-Metall ic Fibers”, Cement andConcrete Composites, Vol. 29, pp. 603-608.