Experimental Approach To Study The Properties Of Fiber Reinforced · PDF file · 2015-04-24Properties Of Fiber Reinforced Fly Ash Based Geopolymer Concrete ... Generally steel, carbon,

2625

www.ijifr.com Copyright © IJIFR 2015

Original Paper

International Journal of Informative & Futuristic Research ISSN (Online): 2347-1697

Volume 2 Issue 8 April 2015

Abstract

The fly ash content influences on the strength parameters, the compressive strength, split, tensile and flexure strength increases with increase in fly ash content to certain extent and decrease with further increases. The optimal flyash content found at 27% for 130 litres of water content. The incorporation of steel fiber in Geopolymer concrete found moderate reduction in compressive strength but significantly increases the split tensile strength and flexure capacity. The cracking moment capacity and ultimate load capacity of the beams were increased with increase in fiber fraction to certain extent which is as expected in ordinary Portland cement concrete. The fiber fractions ranging from 0.6% to 1.0 % with an aspect ratio of 75 have significant influence to increase flexure strength up to 11.5 %.

Experimental Approach To Study The

Properties Of Fiber Reinforced Fly Ash

Based Geopolymer Concrete Paper ID IJIFR/ V2/ E8/ 037 Page No. 2625-2635 Subject Area Civil Engineering

Key Words Geopolymer Concrete, Fly Ash Concrete, Geopolymer Binders, GPC, Polymers

Fibre Reinforced Concrete

Kumar. S 1

Assistant Professor

Department Of Civil Engineering

Jyothy Institute Of Technology, Bangalore -Karnataka

Pradeepa. J 2

Structural Engineer,

Structural Department, Design Tree Consultant Pvt. Ltd.,

Bangalore, Karnataka, India.

Dr. Ravindra P.M. 3

Associate Professor

Department Of Civil Engineering,

Bangalore Institute Of Technology,

K R Road- Bangalore, Karnataka, India

Dr. Rajendra. S 4

Professor & HOD

Department Of Civil Engineering,

Nagarjuna College Of Engineering And Technology

Bangalore. Karnataka, India

2626

ISSN (Online): 2347-1697 International Journal of Informative & Futuristic Research (IJIFR)

Volume - 2, Issue - 8, April 2015 20th Edition, Page No: 2625 - 2635

Kumar.S, Pradeepa.J, Dr.Rajendra. S, Dr Ravindra .P.M:: Experimental Approach To Study The Properties Of Fiber Reinforced Fly Ash Based Geopolymer Concrete

1. Introduction

The fibers are commonly used to improve the mechanical properties of concretes such as tensile

strength, flexure capacity and fracture toughness. Generally steel, carbon, glass fibers are used to

increase the fracture toughness and flexure capacity of the structural element, for the present study

steel fibers are incorporated with fly ash based Geopolymer concrete. An experimental program is

conducted to study the properties of fiber reinforced fly ash based Geopolymer concrete. The effect

of fly ash and fiber content on cube compressive strength, split tensile strength and on flexure

behavior is undertaken in the present study.

The structural application of Geopolymer concrete provides effective durability and strength over

conventional Portland cements concrete. The behavior of the concrete depends upon the source

materials or pozzolanas and activator solution or alkaline solution. From past one decade the

effective research works are being carried in France, America, Australia and India about

Geopolymer binders and still lot of works are yet to be carried to establish the engineering properties

of Geopolymer under structural applications.

Since this is a new era concrete and limited experimental investigations are carried in structural

applications, the efforts are taken to conduct the experimental investigation on Geopolymer concrete

particularly about flexural behavior. This work is planned to conduct the experiment and present the

behavior of “low calcium fly ash based tensile reinforced Geopolymer concrete with steel fibers.”

2. Materials Used

I. Fly ash

In the present experimental work, low calcium, Class F (American Society for Testing and Materials

2001) fly ash is used and it is obtained from the silos of Raichur thermal Power station, RTPCL,

Southern India. The physical and chemical properties of the fly ash presented in Table 1

Table 1: Physical and chemical Properties of fly ash

Sl. No Description Values Requirement as

per IS:3812:2003

Physical property

1 Specific gravity 2.05 -----

2 Fineness (Blain’s air permeability- m2 /kg) 333 320

Chemical properties

3 SiO2 (% by mass) 62.92 35

4 Al2O3 (% by mass) 30.96 ------

5 SiO2 + Al2O3 + Fe2O3 (% by mass) 93.88 70

6 Mg O (% by mass) 0.74 5

8 Total sulphur as sulphur trioxide S O3(% by mass) 0.23 3

9 Loss of ignition (% by mass) 0.59 5

2627




Aggregates

Coarse aggregate

Locally available crushed (angular) granite of maximum size 12.5 mm is used as coarse

aggregate confirming to IS 383. The Specific gravity of coarse aggregate is 2.62 and Water

absorption is 0.3 %

Fine aggregate

Locally available river sand is used as fine aggregate confirming to IS 383.Fineness modules of fine

aggregate is 2.64 and Specific gravity is 2.61.

II. Alkaline Solution

A combination of sodium silicate solution and sodium hydroxide solution was used to react with the

aluminium and the silica in the fly ash. Flake form sodium hydroxide with 97% purity and sodium

silicate from local supplier was used for the present study. The chemical composition of sodium

silicate solution are Na2O=14.74%, SiO2=31.45%, and water content= 33.75% by mass. The

molarity of the solution is kept 16M for thought experimental work.

III. Steel fiber

The plain rounded steel wires are used as fiber. The properties of steel fibers are presented in the

table 2 Table 2: Properties of steel fiber

IV. Water

Clean potable water is used for solution preparation. The total water in the solution is considered as

added water plus the water content in the sodium silicate

V. Super plasticizers:

Poly carboxylic ether based high performance super plasticizers of the brand name GleniumB233

confirmed with IS 9103: 1999, from BASF construction chemicals was used for all the experimental

mix. The dosage applied in the range of 1% to 2% of cementitious material (fly ash) by mass for

better workability.

VI. Mix proportioning

The mixtures named as FGC-M (Fly ash based Geopolymer concrete mixture) were prepared by

varying fly ash content from 15% to 31% of total particulate matter with increments of 2%. The ratio

of sodium silicate to sodium hydroxide kept constant at 2.5 for all series of mixture. The mixtures

were prepared with water content of 135 litres per cubic meter of concrete. The detail of mixture

proportions are presented in table 3.

Table 3: Details of mixture proportion.

Mixtures Fly ash

%

Fly ash

kg/m3

Coarse

aggregate

kg/m3

Fine

aggregate

kg/m3

NaOH

kg/m3

Na2 SiO3

kg/m3

Plasticizer

kg/m3

FGC-M1 15 312.86 992.82 780.08 89.78 224.46 3.13

FGC-M2 17 354.58 969.46 761.72 89.77 224.45 3.54

FGC-M3 19 396.29 946.10 743.37 89.77 224.45 3.96

Properties Values

Length 45 mm

Diameter 0.6mm

Specific Gravity 7.85

Young’s Modulus 200 GPA

Aspect ratio 75

Water Absorption 0%

2628




FGC-M4 21 438.01 922.74 725.01 89.77 224.45 4.38

FGC-M5 23 479.73 899.38 706.66 89.77 224.45 4.80

FGC-M6 25 521.44 876.02 688.30 89.76 224.44 5.21

FGC-M7 27 563.16 852.66 669.94 89.76 224.44 5.63

FGC-M8 29 604.87 829.30 651.59 89.76 224.44 6.05

FGC-M9 31 646.59 805.94 633.23 89.75 224.43 6.46

3. Compressive Strength Of The Concrete

3.1: Compressive Strength Test

The compressive strength test is conducted 150x150x150 mm concrete cubes. Three number of

cubes prepared on each mixtures specified in table 2 and tested through compressive testing

machine. Table 4 shows the compressive strength of the specimens.

Table 4: Compressive strength of cube specimen

Mixtures % of fly

ash

Density

(KN/m3)

Load (kN)

Compressive

strength

fck (N/mm2)

Average

compressive

strength (N/mm2)

FGC-M1 15

23.53 405 18

17.48 23.37 385 17.11

23.45 390 17.33

FGC-M2 17

23.49 440 19.56

19.92 23.37 475 21.11

23.33 430 19.11

FGC-M3 19

23.46 610 27.11

26.59 23.57 590 26.22

23.54 595 26.44

FGC-M4 21

23.58 630 28.00

28.44 23.66 655 29.11

23.64 635 28.22

FGC-M5 23

23.67 695 30.89

31.55 23.63 725 32.22

23.59 710 31.56

FGC-M6 25

23.67 785 34.89

35.25 23.59 805 35.78

23.53 790 35.11

FGC-M7 27

23.63 805 35.78

37.11 23.56 835 37.11

23.69 865 38.44

FGC-M8 29

23.46 745 33.11

33.55 23.38 785 34.89

23.68 735 32.67

FGC-M9 31

23.49 640 28.44

28.07 23.35 660 29.33

23.58 595 26.44

2629




3.2: Flexural Strength Test

The Geopolymer concrete mixtures FGC-M6, FGC-M7 and FGC-M8 (Optimal compressive

strength mixtures) were used for the flexural strength. Tests carried on 100 X 100 X 500 mm

specimens according to IS: 516-1959, the tests results are shown in Table 5

Table 5: Flexural strength of specimens

Mixtures Load P

(kN)

Distance From

fracture to nearer

support (mm)

Flexural

strength

fcr=PL/bd2

(N/mm2)

Average Flexural

strength

(N/mm2)

FGC-M6

10 178 4.0

4.26 11.5 135 4.6

10.5 183 4.2

FGC-M7

11 165 4.4

4.46 .10.5 167 4.2

12 178 4.8

FGC-M8

9.5 174 3.8

4.13 10.5 166 4.2

The fibres were mixed by weight fractions of 0.2 % to 1.2% of fly ash with Mix composition of

FGC-M7 Mixture, selected based on the optimized compressive strength and flexural strength,

shown in table 4&5. The fibre reinforced mixture are named here as FFGC Mixtures (Fibre

reinforced Fly ash based Geopolymer Concrete mixture)

4. Tests on FFGC-Mixtures and Specimens

4.1:Work ability test of FFGC-Mixtures

Slump test, Vee-Bee tests were conducted in similar way as FGC-Mixture and the value presented in

the table 6

Table 6: Workability Test Result

Mixtures

Fiber (%)

Slump (mm)

Vee -Bee test (seconds)

FFGC-M1 0.2 198 33

FFGC-M2 0.4 165 36

FFGC-M3 0.6 115 40

FFGC-M3 0.8 109 43

FFGC-M4 1.0 105 45

FFGC-M5 1.2 84 47

FFGC-M6 1.4 75 52

2630




Figure 1: Effect of fiber content on slump

Figure 2: Effect of fiber content on Vee-Bee degree

Table 6, Fig. 1 and 2 shows the slump and Vee-Bee cosistometer test results. As the fiber volume

fraction increases the flow ability of concrete or subsidence of concrete decreases because of

internal friction with matrix and fiber. The duration to collapse conical shape of the concrete in

Vee-Bee cosistometer was increased with increase in fiber volume fraction. The work ability is

quite important aspect along with the strength parameter. While selection of mixture both

strength and considerable workability parameters were observed.

50

70

90

110

130

150

170

190

210

0 0.5 1 1.5

Slu

mp i

n (

mm

)

% of fiber

30

35

40

45

50

55

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

Vee

-bee

in (

sec)

% of fiber

2631




4.2: FFGC Compression Strength Test

Table 7: FFGC 7th

day Compressive strength results

Mixtures % of

fiber

Density

(KN/m3)

Load

(kN)

Compressive

strength

fck (N/mm2)

Average

compressive

strength (N/ mm2)

FFGC-M1 0.2

23.53 800 35.55

35.4 23.37 805 35.77

23.45 785 34.88

FFGC-M2 0.4

23.49 765 34.00

33.92 23.37 775 34.44

23.33 750 33.33

FFGC-M3 0.6

23.46 735 32.66

32.66 23.57 715 31.77

23.54 715 31.77

FFGC-M4 0.8

23.58 755 33.53

33.54 23.66 765 33.77

23.64 750 33.33

FFGC-M5 1.0

23.67 710 31.55

30.95 23.63 685 30.44

23.59 695 30.88

FFGC-M6 1.2

23.67 680 30.22

30.66 23.59 710 31.55

23.53 680 30.22

FFGC-M7 1.4

23.63 680 30.22

30.59 23.56 700 31.11

23.69 685 30.44

Figure 3: Effect of fiber content on compressive strength

30

31

32

33

34

35

36

0 0.5 1 1.5

Com

pre

ssiv

e st

rength

(N/m

m2)

% of fiber

2632




Table 6.8 and Fig 6.13 show the decrease in compression strength with increase in fiber content up

to 0.6 % and at 0.8% there slight increment in compressive strength was observed This trend is some

time may similar with fiber reinforced OPC concrete; it may be due to the void between fiber and

matrix.

Figure 4: Comparison of compressive strength

4.3: FFGC Flexure Test

The specimens with varying percent of fiber from 0.6% (FFGC-M3) to 1.2% (FFGC-M7) were

tested to study the effect of flexure with respect to fiber content.

Table 8: FFGC 7th

day Flexure test Results

Mixtures

Load

P

(kN)

Distance

From fracture to

nearer support

(mm)

Flexural strength

fcr=PL/bd2

(N/mm2)

Average

Flexural strength

(N/mm2)

FFGC-M3

13 163 5.2

5.06 12.5 116 5.0

12.5 183 5.0

FFGC-M4

13 165 5.2

5.13 13.5 167 5.4

12.0 178 4.8

FFGC-M5

13.5 174 5.4

5.33 13.5 166 5.4

13.0 168 5.2

FFGC-M6

12.5 174 5.0

4.93 12.0 166 4.8

12.5 168 5.0

FFGC-M7

10.5 174 4.2

4.46 12.0 166 4.8

11.0 168 4.4

0

5

10

15

20

25

30

35

40

Com

pre

ssiv

e st

rength

(N

/mm

2)

2633




Figure 5: Effect of fiber content on flexure strength

Figure 6: Comparison of flexure strength

Table 7 and Fig 5 present the effect of fiber on flexure strength. The flexure value of 5.06, 5.13,

and 5.33 N/mm2 were found for the fiber content of 0.6%, 0.8%, 1.0% respectively. The trend

shows the rise in the flexure capacity from 0.6% to 1 % of fiber content and then the decrement

in strength observed on further addition. Fig 6 shows the increasing flexure of FFGC-Mixture to

FGC-M7, through addition of fibers. The percentage of increment in flexure observed is 13.3%,

15% and 19.5% with fiber content of 0.66%, 0.8%,and 1.0% respectively over the FGC-M7

flexure strength.

4

4.5

5

5.5

6

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

Fle

xura

l st

rength

(N

/mm

2)

% of fiber

4

4.2

4.4

4.6

4.8

5

5.2

5.4

Fle

xura

l st

rength

(N

/mm

2)

2634




4.4: FFGC Split tensile strength test

Table 9: FFGC split tensile test Results

Mixture Load P

(kN)

Split tensile

strength

fct=2P/πld

(N/mm2)

Average split

tensile strength

(N/mm2)

FFGC-M3

210 2.97

2.99 220 3.11

205 2.89

FFGC-M4

235 3.32

3.32 240 3.39

230 3.25

FFGC-M5

235 3.32

3.34 245 3.39

235 3.32

Figure 7: Comparison of split tensile strength

Table 9 and Fig 7 present the split tensile strength results. The higher value of split tensile strength

observed for the FFGC-M5 with fiber content of 1.0% .The trend shows the split strength increases

with flexure strength.

Fig 6 shows the increasing flexure of FFGC-Mixture to FGC-M7, through addition of fibers. The

percentage of increment in split tensile were observed is 1.7%, 9.52% and 13.5% with fiber

content of 0.6%, 0.8%,and 1.0% respectively over the FGC-M7 split tensile strength.

Based on these test parameters three mixtures were selected with optimal percentage of fiber and

higher strength. The mixture FFGC-3, FFGC-4, FFGC-5, with fiber content of 0.6%, 0.8% and 1%

respectively were selected for manufacturing of beam specimens.

5. Conclusion

I. The increase in fiber volume fraction with same fly ash and water content in the mixture

decreases the workability. The work ability can be improved by adding super plasticizer

2.7

2.8

2.9

3

3.1

3.2

3.3

3.4

Spli

t te

nsi

le s

tren

gth

(N/m

m2)

2635




with the dosage of 1% to 2 %. The mix becomes very stiff and incompatible to handle with

further addition of fiber beyond 1.4%

II. Fiber reinforced Geopolymer concrete shows decrease in compressive strength compared to

concrete without fibers for the same mixture proportion.

III. Fiber reinforced Geopolymer concrete shows increase in flexure and split tensile strength

compared to concrete without fibers for the same mixture proportion.

IV. FGC-Mixture shows the proportional increase in flexure with compressive strength as

expected in OPC-Concrete, but the FFGC-Mixture shows decrease in compressive strength

and increase in flexure and split tensile strength. Due to this property of the FFGC-Mixture

it could be important to investigate the compressive strength with respect to required flexure

strength for design of structural elements.

V. The fiber volume fraction found effective and give optimal compressive strength at 0.8%

with the aspect ratio of 75 for the specified fiber used in the investigation.

VI. FFGC-Beams shows increase in cracking moment and flexure capacity with increase in fiber

content of the mixture compared to FGC-Beams.

References [1] Davidovits.J.(1994). “Global warming impact on the cement and aggregate industries” world resource

review.Vol-6,No-2, pp 269-273.

[2] Diagloes, felipe, clelio, (2006). “High performance fiber reinforced Geopolymer concrete for pavement”.

Second international airport conference: planning infrastructure and environment. August 2-4(2006) Sao

Paulo – Brazil.

[3] Dylmar Penteado Dias, Clelio Thaumaturgo (2004) "Fracture toughness of Geoplymer concrete

reinforced with basalt fiber” ELSEVIER, Cement and concrete composite 27 (2005) pp 49-54.

[4] Hardjito,.D., and Rangan, B. V. (2005). “Development and properties of low calcium fly ash based

Geopolymer concrete”, Research Report GC1Curtin University of technology Perth, Australia.

[5] Perumal .P, and. Elangovan.G (2009) “Correlation of Experimental and Theoretical Strength of

Superplasticised Steel Fiber Reinforced Concrete" International Journal of Engineering Studies. ISSN

0975- 6469 Volume 1, Number 2 (2009), pp. 139–148

[6] Rangnath .R.V., and Mohammad saleh.(2008). “some optimal values in Geopolymer concrete

incorporating fly ash” Indian concrete journal October 2008 pp 26 -35.

[7] Sumajouw M.D.J. and Rangan, B. V. (2006). “low calcium fly ash based Geopolymer concrete:

Reinforced beams and columns”,Research Report GC 3,Curtin University of technology Perth, Australia.

[8] Susan, bernal, ruby.(2006). “performance of Geopolymer reinforced with steel fiber” IIBC 10th

inorganic-Bonded fiber composite conference.November 15-18,(2006).Sao Paulo Brazil.

[9] Wallah.S.E. and Rangan, B. V. (2006).“Low calcium fly ash based Geopolymer concrete”, Research

Report GC 2,Curtin University of technology Perth, Australia.

[10] Zongjin, Li, Yunsheng Zhang, and Xiangming Zhou. (2005). “Short Fiber Reinforced Geopolymer

Composites Manufactured by Extrusion technique” Journal of materials in civil ASCE / Nov-Dec (2005)

pp-624-631.

Documents

Experimental Approach To Study The Properties Of Fiber Reinforced · PDF file · 2015-04-24Properties Of Fiber Reinforced Fly Ash Based Geopolymer Concrete ... Generally steel, carbon,