This document summarizes a study on the behavior of alkali-activated fly ash-based geopolymer concrete. The study investigated the effect of different activator ratios on the properties of geopolymer concrete. Specimens were prepared with activator ratios of 1:2, 1:2.5, and 1:3. Testing showed the 1:3 ratio produced the highest compressive, split tensile, and flexural strengths at all ages. Strengths increased substantially with curing time. The 1:3 ratio also provided the most economical mix. Therefore, an activator ratio of 1:3 is recommended to achieve maximum strength in fly ash-based geopolymer concrete.

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International Journal of Civil Engineering and Technology (IJCIET)
Volume 8, Issue 1, January 2017, pp.
Available online at http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=8&IType=1
ISSN Print: 0976-6308 and ISSN Online: 0976
© IAEME Publication Scopus
STUDY ON BEHAVIOR OF
FLYASH BASED GEOPOLY
PG Student,
Assoc. Professor, Civil Engineering Department,
ABSTRACT
Objectives: This study is to identify the effect of parameter such as Activator ratio that
affects the properties of alkali activated fly ash
Methodology: To achieve the above objectives, the present investigation is adopted a
technology that is currently in use to manufacture and to test the
main aim of this activity was to facilitate promotion of new materials later on to the concrete
industry. Research variable included activator ratio (1:2, 1:2.5, and 1:3). The trial mix is
prepared for the molarity of 16 M. Concrete specimens were cured at roo
response variables are Flexural strength, Compressive strength and Split tensile strength.
Findings: Test data are used to identify the variation of Geopolymer concrete properties
which are affected by using of various activator ratios and curing period. At all ages, the
activator ratio 1:3 gives maximum strength and also economical when compared to other
activator ratios. There is substantial gain in compressive strength of fly ash based geopolymer
concrete with age.
Improvements: This work can be enhanced for various molarities under various
temperatures and various activator ratios.
Key words: Geopolymer concrete, Molarity, Strength, Activator ratio.
Cite this Article: Ch. Hema Sindhusha and V. Ranga Rao
Activated Flyash based Geopolymer Concrete
Technology, 8(1), 2017, pp. 728
http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=8&IType=1
1. INTRODUCTION
Demand for concrete is increasing day by day
decomposition of raw materials resulting in emissions of C
environment. Geopolymer concrete had been introduced to reduce the environmental pollution
substitutes the cement with consequence such as fly ash, rice
IJCIET/index.asp 728
International Journal of Civil Engineering and Technology (IJCIET)
Volume 8, Issue 1, January 2017, pp. 728–733 Article ID: IJCIET_08_01_086
http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=8&IType=1
6308 and ISSN Online: 0976-6316
Scopus Indexed
STUDY ON BEHAVIOR OF ALKALI ACTIVATED
FLYASH BASED GEOPOLYMER CONCRETE
CH. HEMA SINDHUSHA
PG Student, Civil Engineering Department,
K L University, A. P, India
V. RANGA RAO
Assoc. Professor, Civil Engineering Department,
K L University, A. P, India
his study is to identify the effect of parameter such as Activator ratio that
s the properties of alkali activated fly ash-based geopolymer concrete.
To achieve the above objectives, the present investigation is adopted a
technology that is currently in use to manufacture and to test the conventional concrete. The
aim of this activity was to facilitate promotion of new materials later on to the concrete
Research variable included activator ratio (1:2, 1:2.5, and 1:3). The trial mix is
prepared for the molarity of 16 M. Concrete specimens were cured at roo
response variables are Flexural strength, Compressive strength and Split tensile strength.
Test data are used to identify the variation of Geopolymer concrete properties
which are affected by using of various activator ratios and curing period. At all ages, the
activator ratio 1:3 gives maximum strength and also economical when compared to other
activator ratios. There is substantial gain in compressive strength of fly ash based geopolymer
This work can be enhanced for various molarities under various
temperatures and various activator ratios.
Geopolymer concrete, Molarity, Strength, Activator ratio.
Ch. Hema Sindhusha and V. Ranga Rao, Study on Behavior of Alkali
Activated Flyash based Geopolymer Concrete. International Journal of Civil Engineering and
728–733.
http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=8&IType=1
Demand for concrete is increasing day by day. Manufacturing of cement requires burning of fuels and
decomposition of raw materials resulting in emissions of CO2 which causes pollution to the
Geopolymer concrete had been introduced to reduce the environmental pollution
substitutes the cement with consequence such as fly ash, rice- husk ash, silica fume, etc. The choice of
editor@iaeme.com
http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=8&IType=1
ALKALI ACTIVATED
MER CONCRETE
his study is to identify the effect of parameter such as Activator ratio that
based geopolymer concrete.
To achieve the above objectives, the present investigation is adopted a
conventional concrete. The
aim of this activity was to facilitate promotion of new materials later on to the concrete
Research variable included activator ratio (1:2, 1:2.5, and 1:3). The trial mix is
prepared for the molarity of 16 M. Concrete specimens were cured at room temperature. The
response variables are Flexural strength, Compressive strength and Split tensile strength.
Test data are used to identify the variation of Geopolymer concrete properties
which are affected by using of various activator ratios and curing period. At all ages, the
activator ratio 1:3 gives maximum strength and also economical when compared to other two
activator ratios. There is substantial gain in compressive strength of fly ash based geopolymer
This work can be enhanced for various molarities under various
Study on Behavior of Alkali
International Journal of Civil Engineering and
http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=8&IType=1
Manufacturing of cement requires burning of fuels and
which causes pollution to the
Geopolymer concrete had been introduced to reduce the environmental pollution
husk ash, silica fume, etc. The choice of

2. Study on Behavior of Alkali Activated Flyash based Geopolymer Concrete
http://www.iaeme.com/IJCIET/index.asp 729 editor@iaeme.com
material for making of geopolymer concrete depends on factors such as availability and economy of
materials. Flyash is naturally occurring residue from combustion of coal. Geopolymer concrete is the
composite material resulting from the mixture of flyash with alkaline liquid, and aggregates. It is a
process for the flyash GPC where the Si and Al in the flyash which reacts with alkaline activators to
form a gel. Finally, geopolymer concrete is formed by using gel which is used to bind the aggregates
and un-reacted materials. Alkaline liquid used in this experiment was, the combination of NaOH and
Na2Sio3. Polymerisation process mainly depends on concentration of sodium hydroxide which is
expressed in terms of molar as well as type of curing. The trial mix is designed for the molarity of 16
M. The alkaline liquid to flyash ratio is 0.45.The main objective of this experiment was to study the
behaviour of geopolymer concrete for various activator ratios at various curing periods.
2. EXPERIMENTAL PROGRAM
2.1 MATERIALS USED
• Class F flyash
• Fine aggregate
• Coarse aggregate of 10 mm size
• Chemicals used : Sodium Hydroxide (NaOH) and Sodium Silicate (Na2SiO3)
• Water (as per the requirement)
2.2 TRIAL MIX PROPORTIONS:
The trial mix proportions are prepared for various activator ratios are shown in Table-1.
Table 1 Trial mix proportions
S. No. Description
Quantities
1:2 1:2.5 1:3
1 Mass of Flyash (kg/m3
) 413.8 413.8 413.8
2 Mass of Coarse Aggregate (kg/m3
) 1260 1260 1260
3 Mass of Fine aggregate (kg/m3
) 540 540 540
4 Liquid to Fly ash Ratio 0.45 0.45 0.45
5 Mass of NaOH Solution (kg/m3
) 62.1 62.1 62.1
6 Mass of Na2 SiO3 Solution (kg/m3
) 124.1 124.1 124.1
2.3 PREPARATION OF ALKALINE LIQUID:
For making sodium hydroxide solution, NaOH flakes were dissolved in tap water. Molarity of sodium
hydroxide was 16M.Therefore 640 grams of NaOH flakes was dissolved in one litre of tap water.
Sodium silicate gel is added to the solution to form complete mix. While casting the specimens, extra
water is added to the concrete mixture based on requirement.
2.4 MIXING & CASTING:
The aggregates and flyash were mixed together for 2-3 minutes. Dry mix was mixed with the prepared
alkaline activator and about another 4 - 5 minutes the wet mixing can be promoted as show in Figure-
1. Then the geopolymer concrete was poured into the moulds and was compacted. Then the top
surface is well finished.

3. Ch. Hema Sindhusha and V. Ranga Rao
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Figure1 Mixing of geopolymer concrete
Figure 2 Compressive & Split tensile strength Tests on Concrete Specimens
Figure 3 Flexural Strength Test on Concrete Specimens

4. Study on Behavior of Alkali Activated Flyash based Geopolymer Concrete
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2.5 CURING:
The moulds were demoulded after 24 hours. Up to 3, 7, 28 days the specimens were kept at ambient
temperature.
3. RESULTS& DISCUSSIONS
3.1 COMPRESSIVE STRENGTH
For cubes, Compressive test was done according to Indian standard specifications. Compressive
strength of various activator ratios for 3, 7, 28 days are shown in Figure-4. At all ages, higher
compressive strength has been observed for the 1:3 activator ratios as compared to other two activator
ratios. Compressive strength increases about 21-56 % with increase in curing period and 2-14 % with
increase in activator ratio.
Figure 4 Effect of activator ratio on Compressive strength
3.2 SPLIT TENSILE STRENGTH
For cylinders split tensile test was done as per Indian specifications. Split tensile strength of various
activator ratios for 3, 7, 28 days are shown in Figure-5. At all ages, higher Split tensile strength has
been observed for the 1:3 activator ratios as compared to other two activator ratios. Split Tensile
strength increases about 42- 90 % with increase in curing period and 8-25 % with increase in activator
ratio.
Figure 5 Effect of activator ratio on Split Tensile strength

5. Ch. Hema Sindhusha and V. Ranga Rao
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3.3 FLEXURAL STRENGTH
For beams, flexural test is conducted as per Indian specifications. Split tensile strength of various
activator ratios for 3, 7, 28 days are shown in Figure-6. At all ages, higher Split tensile strength has
been observed for the 1:3 activator ratios as compared to other two activator ratios. Split Tensile
strength increases about 51-78 % with increase in curing period and 16-53 % with increase in activator
ratio.
Figure 6 Effect of activator ratio on Flexural strength
Table 2 Various Strength Parameters of Geopolymer Concrete
S. NO NO. OF DAYS
COMPRESSIVE
STRENGTH
(N/mm2
)
SPLIT TENSILE
STRENGTH
(N/mm2
)
FLEXURAL
STRENGTH
(N/mm2
)
1:2 1:2.5 1:3 1:2 1:2.5 1:3 1:2 1:2.5 1:3
1 3 days 8.63 8.85 9.50 0.22 0.24 0.27 0 0.46 0.59
2 7 days 11.03 11.42 12.12 0.38 0.83 0.87 0.52 1.12 1.22
3 28 Days 18 20.5 21 2 2.4 2.7 1.76 2.12 2.3
4. CONCLUSIONS
From the experimental investigation following conclusions were drawn.
• Compressive strength increases substantially with increase of an activator ratio and age.
• The split tensile strength increases with increase of an activator ratio and curing period.
• Flexural strength also increases about 51- 78% with increase in curing period and 16- 53% with
increase in activator ratio.
• At all ages, the activator ratio 1:3 gives maximum strength and also economical when compared to
other two activator ratios.

6. Study on Behavior of Alkali Activated Flyash based Geopolymer Concrete
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[10] Mohd Mustafa Al Bakri1 (2011). Review on fly ash-based geopolymer concrete without Portland
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