fly ash is a noncombustible material obtained from the various thermal power plants. Since fly ash is available in large scale, it is disposed of in rivers and landfills and ponds by thermal industries which are posing danger to environment. Due to high pozzolanic activity of fly ash, efforts are being made to use it as a cement replacement material. GeoPolymer concrete makes 100 percent utilization of fly ash in concrete along with alkaline solutions, as a binder. The cube specimens and beams are casted for 2% and 4% super plasticizers and alkaline to fly ash ratio of 0.35. The compressive strength of cubes is compared to that of conventional cubes at 7, 14 and 28 days .it is observed that GeoPolymer concrete is economical as compared to normal concrete from compressive strength point of view.

1. IJSRD - International Journal for Scientific Research & Development| Vol. 2, Issue 07, 2014 | ISSN (online): 2321-0613
All rights reserved by www.ijsrd.com 280
Study on Strength of Fly Ash Based GeoPolymer Concrete under Heat
Curing
Bagwan Mustafa1
Shaik Abdulla2
1
P.G. Student 2
Lecturer
1,2
Department of Civil Engineering
1,2
Khaja Bandanawaz College of engineering, Gulbarga, Karnataka.
Abstract— fly ash is a noncombustible material obtained
from the various thermal power plants. Since fly ash is
available in large scale, it is disposed of in rivers and
landfills and ponds by thermal industries which are posing
danger to environment. Due to high pozzolanic activity of
fly ash, efforts are being made to use it as a cement
replacement material. GeoPolymer concrete makes 100
percent utilization of fly ash in concrete along with alkaline
solutions, as a binder. The cube specimens and beams are
casted for 2% and 4% super plasticizers and alkaline to fly
ash ratio of 0.35. The compressive strength of cubes is
compared to that of conventional cubes at 7, 14 and 28 days
.it is observed that GeoPolymer concrete is economical as
compared to normal concrete from compressive strength
point of view.
Key words: GeoPolymer concrete, fly ash, sodium silicate,
sodium hydroxide
I. INTRODUCTION
In normal concrete cement is used for hydration process to
takes place to form binders mainly silicates and aluminates
and for gel component to bond the aggregates each other,
hydration process is activated by the reaction between
cement with water which gives rise to binders. So, to invent
alternate concrete, it should form binders in anyway without
the use of cement. This gave rise to the invention of
GeoPolymer concrete. There are two main constituents of
GeoPolymer, namely the source materials and the alkaline
liquids. GeoPolymer concrete is made by using 100 % of fly
ash instead of cement. In GeoPolymer concrete fly ash is
activated using alkaline solution to form binders . The
alkaline liquids are from soluble alkali metals that are
usually Sodium or Potassium based. The most common
alkaline liquid used in geopolymerization is a combination
of sodium hydroxide (NaOH) or potassium hydroxide
(KOH) and sodium silicate or potassium silicate. The
complete geopolymerization process yields a Si-O-Al-O
bonds in an amorphous form.
II. NEED OF THE STUDY
The fact that production of cement leads to the pollution of
environment is a well-known fact to civil engineers and
environmentalists. The mass production of cement is posing
environmental hazard on one hand and unrestricted
depletion of natural resources on the other hand. It is
estimated that production of Each ton of Portland cement
production results in loading about one ton of CO2 into the
environment. To meet the infrastructure demand in real
estate and commercial industry, there is no way to stop the
cement production for more concrete. In order to overcome
this difficulty, a new decade concrete called as GeoPolymer
concrete is used in combination with admixture such as
super plasticizers.
III. OBJECTIVES OF THE STUDY
 To study the effect of super plasticizer on strength
of GeoPolymer concrete at variable percentages
such as 2% and 4%.
 To conduct the experiment to determine the
compressive strength of M 25 grade concrete and
8M,12Mand 16M GeoPolymer concrete at 7,14
and 28 days.
 To determine ultimate loading capacity of
8M,12Mand16M GeoPolymer concrete beams at
28 days
IV. EXPERIMENTAL ANALYSIS
The present investigation involves 100% replacement of
cement by fly ash (ASTM type class F) of low calcium
content. The super plasticizer incorporated is SP430 in 2%
and 4% proportion, to increase the workability of
GeoPolymer concrete as it is very cohesive in nature, due to
mixture of alkaline solution consisting of sodium silicate
(Na2SiO3) and sodium hydroxide (NaOH) .The ratio of
sodium silicate solution to sodium hydroxide solution is
kept as 2.5.The ratio of alkaline solution to the fly ash is
maintained to 0.35 only. To examine the compressive
strength ,sodium hydroxide solutions of varying molarities
are prepared i.e. 8M,12M and 16M for instance, sodium
hydroxide solution with a concentration of 8M consists of
8x40=320grams of sodium hydroxide solids (in pellet form)
per liter of the solution, where 40 is the molecular weight of
sodium hydroxide. The mass of sodium hydroxide solids
was measured as 262grams per Kg of sodium hydroxide
solution of 8 molar concentrations. Similarly the mass of
sodium hydroxide solids per Kg of the solution for other
concentration was measured as 12 molar : 361 grams, 16
molar: 444 grams. note that the mass of sodium hydroxide
solids was only a fraction and water was the major
component .for conventional specimens of M25 grade
concrete the proportion was (1:2.20:3.90) . Among the
materials to be used, locally available river sand was used
and normal coarse aggregates of 12mm and 20mm down
size were used for concrete mix.
A. Mixing and Curing Of Geopolymer Concrete
In the laboratory, the fly ash and the aggregates were first
mixed together in dry state. The alkaline solution consisting
of sodium silicate and sodium hydroxide solution were
mixed 1 day prior to casting. The alkaline liquid was mixed
with the super plasticizer and the extra water, if any. The
liquid component of the mixture was then added to the dry
materials and the mixing continued usually for another 10 -
15 minutes. The fresh concrete could be handled up to 120
minutes without any sign of setting and without any
degradation in the compressive strength. The concrete mix

2. Study on Strength of Fly Ash Based GeoPolymer Concrete under Heat Curing
(IJSRD/Vol. 2/Issue 03/2014/064)
All rights reserved by www.ijsrd.com 281
was then used to cast cube specimens of 150x150x150mm
size. The fresh concrete was cast and compacted by the
usual methods used in the case of Portland cement concrete
(Hardjito and Rangan, 2005; Sumajouw and Rangan, 2006)
[3],[4]. fresh fly ash-based geopolymer concrete was usually
cohesive. The workability of the fresh concrete was
measured by means of the conventional slump test. The
compressive strength of geopolymer concrete is influenced
by the wet-mixing time. Test results show that the
compressive strength increased as the wet-mixing time
increased (Hardjito and Rangan, 2005) [3].The casted
specimens were wrapped by plastic sheet to avoid moisture
loss .The specimens were then placed in an oven at 60o
C for
24 hours ,because geopolymerization process requires high
temperature curing initially ,then they were left to room
temperature until testing.
B. Testing Of Cubes
The cube specimens of 150mmx150mmx150mm size were
tested in compression testing machine of 200T capacity. The
cubes were tested for 7,14and 28 days compressive strength
Molarity
No of
cubes
No
of
days
Compressive strength
(N/mm2
)
8M
03 7 20.78 17.06
03 14 28.35 24.16
03 28 34.0 28.92
12M
03 7 23.06 16.66
03 14 30.21 26.03
03 28 37.28 31.62
16M
03 7 29.85 23.25
03 14 41.56 38.56
03 28 43.41 39.06
M25
03 7 15.14 10.70
03 14 23.11 16.44
03 28 28.33 23.20
Table. 1: Compressive Strength At2% And 4% Super
plasticizers
C. Casting of Beams
Eight beams of size 100x150x1800mm were casted, to
determine the ultimate loading capacity of beams. Two
beams corresponding to each molarities i.e. 8M,12Mand
16M as well as conventional M25 grade beams ,all with
reinforcement details as show below were casted. Cross
sectional details of reinforcement in beams
D. Test Setup
Test was carried out in a loading frame of 1000KN capacity.
Dial gauges with least count 0.01 were fixed to measure
deflection at different load level. All beams were tested with
two point loads applied at 1/3 of span of the beam , so as to
have a pure bending zone in the middle of the beam. The
beam was placed such that the center of the beam and the
center of the loading frame lie on the same line as per the
required effective span of 1600mm.
Fig. 1: test setup in loading frame
E. Load – Deflection Behavior
The load deflection behavior is shown in figures below. The
ultimate load value for geopolymer concrete beams is higher
as compared to conventional ones, it is about 1.5 times more
than M25 grade conventional concrete beams and maximum
ultimate loading capacity is exhibited by 16M beams.
Deflections observed are also within allowable limits as per
IS 456-2000.
BEAM
DESIGNATION
CONCRETE
MIX
FIRST
CRACKING
LOAD KN
ULTIMATE
LOAD KN
CV1-1 M-25 40 80
CV1-2 M-25 43 95
B2-1 8M 42 85
B2-2 8M 45 110
B3-1 12M 43 100
B3-2 12M 47 115
B4-1 16M 46 105
B4-2 16M 52 140
Table. 2: Load Deflection Behavior
Fig. 2
Fig. 3
0
50
100
0 5 10
LOADINKN
DEFLECTION IN MM
CV1-2

3. Study on Strength of Fly Ash Based GeoPolymer Concrete under Heat Curing
(IJSRD/Vol. 2/Issue 03/2014/064)
All rights reserved by www.ijsrd.com 282
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9
V. CONCLUSION
 The increase in compressive strength is observed when
the Na2SiO3 to NaOH ratio is 2.5.
 While casting it is seen that the geopolymer concrete
mix is very cohesive and sticky. As the super
plasticizer content increases from 2% to 4% the
decrease in the compressive strength is 10%. But for
2% super plasticizer content the workability of the mix
is not good as compared to 4% super plasticizer
content. And for 4% content the setting time of the
concrete is prolonged for placing specimen in
accelerated curing chamber. Due to the cohesive mix
the tamping should done very carefully and correctly
otherwise pores will be formed in the specimens that
leads to decrease in compressive strength.
 Increase in concentration of NaOH from 12M to 16M
resulted in increase of 21% ultimate load of beams
 For 12M and 16M conc. Of NaOH only a minimum
difference in deflections are observed. Where
deflection is the criteria for design of geopolymer
concrete beams 12M conc of NaOH can be used for
economy. Where ultimate load is the criteria for design
of geopolymer concrete beams 16M conc of NaOH can
be used.
 For three conc of NaOH i.e 8M,12M and 16M the
ultimate load increased with increase in conc of NaOH.
Ultimate load of geopolymer concrete beams is 1.5
times higher than the obtained ultimate load for normal
concrete. Maximum ultimate load is represented by
16M beams.
REFERENCE
[1] Robert Mccaffrey., (2002). “Climate Change And The
Cement Industry”, Conference On Market And
Economic Trends Influencing The Global Cement
Industry.
[2] Davidovits, J., (1988). “Soft Mineralogy and
Geopolymers”, Proceedings of the of Geopolymer 88
International Conference, the Université de
Technologie, Compiègne, France.
[3] D. Hardjito and B. V. Rangan., (2005). “Development
And Properties Of Low-Calcium Fly Ash-Based
Geopolymer Concrete”, Research Report GC 1,
Faculty of Engineering Curtin University of
Technology Perth, Australia.
[4] M. D.J. Sumajouw and B. V. Rangan., (2006). “Low-
Calcium Fly Ash-Based Geopolymer Concrete:
Reinforced Beams And Columns”, Research Report
0
20
40
60
80
100
0 5
LOADINKN
DEFLECTION IN MM
B2-1
0
50
100
150
0 2 4
LOADINKN
DEFLECTION IN MM
B2-2
0
50
100
150
0 5
LOADINKN
DEFLECTION IN MM
B3-1
0
50
100
150
0 2 4
LOADINKN
DEFLECTION IN MM
B3-2
0
50
100
150
0 2 4 6
LOADINKN
DEFLECTION IN MM
B4-1
0
50
100
150
0 2 4 6
LOADINKN
DEFLECTION IN MM
B4 -2

4. Study on Strength of Fly Ash Based GeoPolymer Concrete under Heat Curing
(IJSRD/Vol. 2/Issue 03/2014/064)
All rights reserved by www.ijsrd.com 283
GC 3, Faculty of Engineering Curtin University of
Technology Perth, Australia.
[5] Wallah, S.E., Hardjito, D., Sumajouw, D.M.J. &
Rangan, B.V., (2003). “Sulfate resistance of fly ash
based geopolymer concrete” In Proceedings of
Concrete in the Third Millenium: Then 21st century
Biennial Conference of the The Concrete Institute of
Australia.
[6] B. Vijaya Rangan., (2008). “Studies On Fly Ash-Based
Geopolymer Concrete”, Malaysian Construction
Research Journal, Vol. 03 [No. 2].
[7] Djwantoro Hardjito, Steenie E. Wallah, Dody M.J.
Sumajouw, and B.V. Rangan., (2004). “Factors
Influencing The Compressive Strength Of Fly Ash
Based Geopolymer Concrete”, Journal of Civil
Engineering Dimension, Vol. 6, No. 2, 88–93, ISSN
1410-9530.
[8] Nguyen Van Chanh, Bui Dang Trung, and Dang Van
Tuan., (2008). “Recent Research Geopolymer
Concrete”, The 3rd ACF International Conference-
ACF/VCA 2008, A.18.
[9] IS 383 : 1970 (reaffirmed 1997) “Specification ForCoarse
And Fine Aggregates From Natural Sources For Concrete”
Second Revision, Bureau Of Indian Standards.