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Original Paper
Volume 2
Issue 8
April 2015
International Journal of Informative & Futuristic Research
ISSN (Online): 2347-1697
Experimental Approach To Study The
Properties Of Fiber Reinforced Fly Ash
Based Geopolymer Concrete
Paper ID
Key Words
IJIFR/ V2/ E8/ 037
Page No.
2625-2635
Subject Area
Civil Engineering
Geopolymer Concrete, Fly Ash Concrete, Geopolymer Binders, GPC, Polymers
Fibre Reinforced Concrete
Kumar. S 1
Pradeepa. J 2
Dr. Ravindra P.M. 3
Dr. Rajendra. S 4
Assistant Professor
Department Of Civil Engineering
Jyothy Institute Of Technology, Bangalore -Karnataka
Structural Engineer,
Structural Department, Design Tree Consultant Pvt. Ltd.,
Bangalore, Karnataka, India.
Associate Professor
Department Of Civil Engineering,
Bangalore Institute Of Technology,
K R Road- Bangalore, Karnataka, India
Professor & HOD
Department Of Civil Engineering,
Nagarjuna College Of Engineering And Technology
Bangalore. Karnataka, India
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 %.
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2625
ISSN (Online): 2347-1697
International Journal of Informative & Futuristic Research (IJIFR)
Volume - 2, Issue - 8, April 2015
20th Edition, Page No: 2625 - 2635
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
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
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ISSN (Online): 2347-1697
International Journal of Informative & Futuristic Research (IJIFR)
Volume - 2, Issue - 8, April 2015
20th Edition, Page No: 2625 - 2635
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.
Properties
Length
Diameter
Specific Gravity
Young’s Modulus
Aspect ratio
Water Absorption
Water
Values
45 mm
0.6mm
7.85
200 GPA
75
0%
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
FGC-M1
FGC-M2
FGC-M3
15
17
19
312.86
354.58
396.29
Coarse
aggregate
kg/m3
992.82
969.46
946.10
Fine
aggregate
kg/m3
780.08
761.72
743.37
NaOH
kg/m3
Na2 SiO3
kg/m3
Plasticizer
kg/m3
89.78
89.77
89.77
224.46
224.45
224.45
3.13
3.54
3.96
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
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ISSN (Online): 2347-1697
International Journal of Informative & Futuristic Research (IJIFR)
Volume - 2, Issue - 8, April 2015
20th Edition, Page No: 2625 - 2635
FGC-M4
FGC-M5
FGC-M6
FGC-M7
FGC-M8
FGC-M9
21
23
25
27
29
31
438.01
479.73
521.44
563.16
604.87
646.59
922.74
899.38
876.02
852.66
829.30
805.94
725.01
706.66
688.30
669.94
651.59
633.23
89.77
89.77
89.76
89.76
89.76
89.75
224.45
224.45
224.44
224.44
224.44
224.43
4.38
4.80
5.21
5.63
6.05
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
FGC-M1
15
FGC-M2
17
FGC-M3
19
FGC-M4
21
FGC-M5
23
FGC-M6
25
FGC-M7
27
FGC-M8
29
FGC-M9
31
Density
(KN/m3)
Load (kN)
23.53
23.37
23.45
23.49
23.37
23.33
23.46
23.57
23.54
23.58
23.66
23.64
23.67
23.63
23.59
23.67
23.59
23.53
23.63
23.56
23.69
23.46
23.38
23.68
23.49
23.35
23.58
405
385
390
440
475
430
610
590
595
630
655
635
695
725
710
785
805
790
805
835
865
745
785
735
640
660
595
Compressive
strength
fck (N/mm2)
18
17.11
17.33
19.56
21.11
19.11
27.11
26.22
26.44
28.00
29.11
28.22
30.89
32.22
31.56
34.89
35.78
35.11
35.78
37.11
38.44
33.11
34.89
32.67
28.44
29.33
26.44
Average
compressive
strength (N/mm2)
17.48
19.92
26.59
28.44
31.55
35.25
37.11
33.55
28.07
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
2628
ISSN (Online): 2347-1697
International Journal of Informative & Futuristic Research (IJIFR)
Volume - 2, Issue - 8, April 2015
20th Edition, Page No: 2625 - 2635
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
FGC-M6
FGC-M7
FGC-M8
Load P
(kN)
Distance From
fracture to nearer
support (mm)
Flexural
strength
fcr=PL/bd2
(N/mm2)
10
11.5
10.5
11
.10.5
12
9.5
10.5
178
135
183
165
167
178
174
166
4.0
4.6
4.2
4.4
4.2
4.8
3.8
4.2
Average Flexural
strength
(N/mm2)
4.26
4.46
4.13
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
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
2629
ISSN (Online): 2347-1697
International Journal of Informative & Futuristic Research (IJIFR)
Volume - 2, Issue - 8, April 2015
20th Edition, Page No: 2625 - 2635
210
190
Slump in (mm)
170
150
130
110
90
70
50
0
0.5
1
1.5
% of fiber
Figure 1: Effect of fiber content on slump
55
Vee-bee in (sec)
50
45
40
35
30
0
0.2
0.4
0.6
0.8
% of fiber
1
1.2
1.4
1.6
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.
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
2630
ISSN (Online): 2347-1697
International Journal of Informative & Futuristic Research (IJIFR)
Volume - 2, Issue - 8, April 2015
20th Edition, Page No: 2625 - 2635
4.2: FFGC Compression Strength Test
Table 7: FFGC 7th day Compressive strength results
Mixtures
% of
fiber
FFGC-M1
0.2
FFGC-M2
0.4
FFGC-M3
0.6
FFGC-M4
0.8
FFGC-M5
1.0
FFGC-M6
1.2
FFGC-M7
1.4
Density
(KN/m3)
Load
(kN)
23.53
23.37
23.45
23.49
23.37
23.33
23.46
23.57
23.54
23.58
23.66
23.64
23.67
23.63
23.59
800
805
785
765
775
750
735
715
715
755
765
750
710
685
695
Compressive
strength
fck (N/mm2)
35.55
35.77
34.88
34.00
34.44
33.33
32.66
31.77
31.77
33.53
33.77
33.33
31.55
30.44
30.88
23.67
23.59
23.53
23.63
23.56
23.69
680
710
680
680
700
685
30.22
31.55
30.22
30.22
31.11
30.44
Average
compressive
strength (N/ mm2)
35.4
33.92
32.66
33.54
30.95
30.66
30.59
Compressive strength
(N/mm2)
36
35
34
33
32
31
30
0
0.5
1
1.5
% of fiber
Figure 3: Effect of fiber content on compressive strength
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
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ISSN (Online): 2347-1697
International Journal of Informative & Futuristic Research (IJIFR)
Volume - 2, Issue - 8, April 2015
20th Edition, Page No: 2625 - 2635
Compressive strength (N/mm2)
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.
40
35
30
25
20
15
10
5
0
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
FFGC-M3
FFGC-M4
FFGC-M5
FFGC-M6
FFGC-M7
Load
P
(kN)
13
12.5
12.5
13
13.5
12.0
13.5
13.5
13.0
12.5
12.0
12.5
10.5
12.0
11.0
Distance
From fracture to
nearer support
(mm)
163
116
183
165
167
178
174
166
168
174
166
168
174
166
168
Flexural strength
fcr=PL/bd2
(N/mm2)
5.2
5.0
5.0
5.2
5.4
4.8
5.4
5.4
5.2
5.0
4.8
5.0
4.2
4.8
4.4
Average
Flexural strength
(N/mm2)
5.06
5.13
5.33
4.93
4.46
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
2632
ISSN (Online): 2347-1697
International Journal of Informative & Futuristic Research (IJIFR)
Volume - 2, Issue - 8, April 2015
20th Edition, Page No: 2625 - 2635
Flexural strength (N/mm2)
6
5.5
5
4.5
4
0.2
0.4
0.6
0.8
1
% of fiber
1.2
1.4
1.6
Figure 5: Effect of fiber content on flexure strength
Flexural strength (N/mm2)
5.4
5.2
5
4.8
4.6
4.4
4.2
4
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.
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
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ISSN (Online): 2347-1697
International Journal of Informative & Futuristic Research (IJIFR)
Volume - 2, Issue - 8, April 2015
20th Edition, Page No: 2625 - 2635
4.4: FFGC Split tensile strength test
Table 9: FFGC split tensile test Results
Mixture
FFGC-M3
FFGC-M4
Split tensile strength
(N/mm2)
FFGC-M5
Load P
(kN)
210
220
205
235
240
230
235
245
235
Split tensile
strength
fct=2P/πld
(N/mm2)
2.97
3.11
2.89
3.32
3.39
3.25
3.32
3.39
3.32
Average split
tensile strength
(N/mm2)
2.99
3.32
3.34
3.4
3.3
3.2
3.1
3
2.9
2.8
2.7
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
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
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ISSN (Online): 2347-1697
International Journal of Informative & Futuristic Research (IJIFR)
Volume - 2, Issue - 8, April 2015
20th Edition, Page No: 2625 - 2635
II.
III.
IV.
V.
VI.
with the dosage of 1% to 2 %. The mix becomes very stiff and incompatible to handle with
further addition of fiber beyond 1.4%
Fiber reinforced Geopolymer concrete shows decrease in compressive strength compared to
concrete without fibers for the same mixture proportion.
Fiber reinforced Geopolymer concrete shows increase in flexure and split tensile strength
compared to concrete without fibers for the same mixture proportion.
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.
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.
FFGC-Beams shows increase in cracking moment and flexure capacity with increase in fiber
content of the mixture compared to FGC-Beams.
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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
2635