Objectives: The intention of the paper is to find their strength characteristics of fly ash based Geo Polymer Concrete (GPC) with varied ratios of alkaline solutions at the age of 3, 7&28 days. Methods: To assess the essence of various parameters i.e. NaOH concentration, Ratio of alkaline solution to fly ash and Ratio of Na2SiO3 to NaOH, curing time the experimental work was carried. In this paper Na2SiO3 to NaOH ratios of 1:2, 1:2.5, 1:3 and Sodium hydroxide solution with 14M concentration and liquid to fly ash ratio is 0.45. Room temperature was used. Findings: For geopolymer binders, the tests have been conducted to evaluate split tensile strength, flexural strength and compressive strength with respect to cylinders, beams and cubes. The outcomes indicated the increment in the strengths with the increase of activator ratio at the age of 3,7&28 days and higher ratio gives higher strength. Improvements: This investigation can be enhanced for various molarities under various temperatures and various activator ratio

1. http://www.iaeme.com/IJCIET/index.asp 431 editor@iaeme.com
International Journal of Civil Engineering and Technology (IJCIET)
Volume 8, Issue 1, January 2017, pp. 431–437, Article ID: IJCIET_08_01_049
Available online at http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=8&IType=1
ISSN Print: 0976-6308 and ISSN Online: 0976-6316
© IAEME Publication
STRENGTH CHARACTERISTICS OF FLY ASH
BASED GEOPOLYMER CONCRETE WITH 14
MOLAR NAOH ACTIVATOR
Hymavathi G
PG Student, Civil Engineering Department,
K L University, Vaddeswaram-522502, A. P, India
Ranga Rao V
Professor, Civil Engineering Department,
K L University, Vaddeswaram-522502, A. P, India
ABSTRACT
Objectives: The intention of the paper is to find their strength characteristics of fly ash
based Geo Polymer Concrete (GPC) with varied ratios of alkaline solutions at the age of 3,
7&28 days. Methods: To assess the essence of various parameters i.e. NaOH concentration,
Ratio of alkaline solution to fly ash and Ratio of Na2SiO3 to NaOH, curing time the
experimental work was carried. In this paper Na2SiO3 to NaOH ratios of 1:2, 1:2.5, 1:3 and
Sodium hydroxide solution with 14M concentration and liquid to fly ash ratio is 0.45. Room
temperature was used. Findings: For geopolymer binders, the tests have been conducted to
evaluate split tensile strength, flexural strength and compressive strength with respect to
cylinders, beams and cubes. The outcomes indicated the increment in the strengths with the
increase of activator ratio at the age of 3,7&28 days and higher ratio gives higher strength.
Improvements: This investigation can be enhanced for various molarities under various
temperatures and various activator ratios.
Key words: Fly Ash, Geopolymer Concrete, Sodium Silicate, Morality, Sodium Hydroxide,
Strength.
Cite this Article: Hymavathi G and Ranga Rao V, Strength Characteristics of Fly Ash Based
Geopolymer Concrete with 14 Molar Naoh Activator. International Journal of Civil
Engineering and Technology, 8(1), 2017, pp. 431–437.
http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=8&IType=1
1. INTRODUCTION
In the manufacturing of concrete OPC becomes an important material and its binds all the aggregate
together which act as its binder 1
. Nevertheless, the usage of cement creates contamination to the
world and it reduces the raw material (limestone)2
. Decayed limestone and large quantities of burned
fuel are required for the production of OPC, it results from carbon dioxide emissions3
So for reducing
the carbon gasses geopolymer concrete had been introduced.

2. Hymavathi G and Ranga Rao V
http://www.iaeme.com/IJCIET/index.asp 432 editor@iaeme.com
Hence, fiery debris based GPC was a brilliant contrasting option to get over the rich of fly
powder. In fiery debris based GPC, the silica and the aluminas are the origin materials and they
initially invited by basic activators to shape a gel known as Aluminosilicate7
. Soluble gel ties the
free totals and the other unreacted materials in the blend to frame the geopolymer solid 8
. This paper
compresses the conduct of geopolymer solid which improves it contrasted with ordinary cement.
2. OBJECTIVE OF THE STUDY
The intention of the paper was to find the strength characteristics of fly ash based GPC with varied
ratios of alkaline solutions at the age of 3, 7&28 days.
3. METHODOLOGY
3.1. MATERIALS USED
3.1.1. Fly Ash
It is an end product obtaining through the coal burning electric yielding plants. It can also be used in
OPC to raise the concrete function. And in this study class-F fly ash is used.
3.1.2. AGGREGATES
Gravels are used as a coarse aggregate of sizes 10mm taken from a local supplier and river sand used
as a fine aggregate from Vijayawada surroundings are used in the present study.
3.1.3. Alkaline Solution
In this study, the alkaline liquid was used which consists of Na2SiO3 and NaOH (flakes form). The
purity of Na2SiO3 &the NaOH is 97%-98% bought in from the local supplier. The NaOH flakes were
melted in water to make the solution.
4. EXPERIMENTAL PROCEDURE
4.1. Preparation of Alkaline Solutions
This study carried by using the 14M i.e mix of molarity of Sodium hydroxide to examined the
strength of geopolymer concrete. The molecular weight of NaOH is 40. For NaOH solution, 560g of
NaOH flakes are taken, weighed and flakes can be melted in a 1-liter solution of water. The alkaline
solution mixed together one day for the preparation of alkaline liquid. While casting the specimens,
to prepare liquid component of mixture extra water is added based on requirement.
4.2. Mix Proportion
For the mix design of GPC, there are no code provisions, 2400 Kg/m3
is assumed as the density of
GPC , and remaining are based on done by following the concrete density and the fine and coarse
aggregates volume occupation adopted as 70%. 0.45 is the water content to fly ash ratio. To prepare
the GPC the conventional method of normal concrete is adopted.
4.3. Mixing and casting of Geopolymer concrete
Initially in container materials were mixed after that alkaline solution is added. This mix is placed in
moulds those are cubes, cylinders beams. The preparation of GPC mix is shown in Figure 1.

3. Strength Characteristics of Fly Ash Based Geopolymer Concrete with 14 Molar Naoh Activator
http://www.iaeme.com/IJCIET/index.asp 433 editor@iaeme.com
Figure 1 Mixing of Geopolymer Concrete
4.4. Curing
The cubes were Demoulded after one day of casting and the casted cubes are laid in the ambient
temperature for three, seven and 28 days, shown in Figure 2.
Figure 2 Casting and Curing of specimens
5. TESTING
The strengths were calculated for three, seven&28 days and the equipment measured those strengths
are Shown in Figure 3.

4. Hymavathi G and Ranga Rao V
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Figure 3 Testing of specimens
6. RESULTS AND DISCUSSION
The various strength parameters of GPC mixes are shown in Table 1.
Table 1 Various Strength Parameters of Geopolymer Concrete
S.NO
NO.OF
DAYS
Compressive
strength
(N/mm2)
Split tensile strength
(N/mm2)
Flexural Strength
(N/mm2)
CUBES CYLINDERS BEAMS
1:2 1:2.5 1:3 1:2 1:2.5 1:3 1:2 1:2.5 1:3
1 3 days 8.5 10 10.96 0.156 0.196 0.225 0 0.24 0.39
2 7 days 11.03 12 12.44 0.667 0.716 0.784 0.48 0.97 1.56
3 28 days 15.06 16.5 17.52 1.22 1.5 1.8 1.52 1.6 1.62
6.1. Compressive Strength
The sizes of specimens for cubes are 150 x 150 x 150(mm) are cast for each mix. One day after the
specimens was laid and Cured for 3, 7&28days. And the Figure 4. Shows the compressive strength
of various activator ratios for 3,7&28 days. For 3days15% of Compressive strength is raised for ratio
1:2.5 compared to 1:2, and 22% of compressive strength is increased for activator ratio 1:3 compared
to 1:25.And for 28days15% of Compressive strength is raised for activator ratio 1:2 compared to
1:25. Average compressive strength value is 13.64 for 28days and is higher than the 3&7 days. So
we can conclude that higher activator ratio gives higher compressive strength and longer curing time
results in higher compressive strength.

5. Strength Characteristics of Fly Ash Based Geopolymer Concrete with 14 Molar Naoh Activator
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Figure 4 Compressive strength of various activator ratios
6.2. Flexural Strength
The beam (specimens) of size 100mm × 100mm × 500mm were used and are cast for each mix,
results are shown in Figure 5. For 3days 38% of flexural Strength is increased for activator ratio 1:3
compared to 1:25 and 6.17% for twenty-eight days. For three days Average flexure strength value is
0.66kn/mm2
and 1.19kn/mm2
for 28 days. So we can conclude that the flexural strength increases
for longer curing period.
Figure 5.Flexuralstrength of various activator ratios
6.3. Split Tensile Strength
Used Sizes of Cylinders are 150 x 150 x 300 (mm) are cast for each mix. After 24 hours the
specimens were de-molded and cured for 3, 7 and 28days. The average of three identical cylinders
is indicated the split tensile strength, results are shown in Figure 6. At the age of 3days, 20% of split
tensile strength is increased for activator ratio 1:2.5 compared to 1:2, and 13% of split tensile strength
is increased for activator ratio 1:3 compared to 1:25. And at the age of 7days15% of split tensile
strength is increased compared to 3days. Average split tensile strength value is 0.936 for 28days and
is higher than the 3&7 days. So we can conclude that higher activator ratio gives higher split tensile
strength and longer curing time results in higher split tensile strength.

6. Hymavathi G and Ranga Rao V
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Figure 6.Split Tensile strength of various activator ratios
7. CONCLUSION
Experimental results are concluded that,
1. Obtained results indicated that 22% of compressive strength was increased for the activator ratio 1:3
as compared to that of 1:2 and 1:2.5.
2. Average compressive strength value was 13.64 N/mm2
for 28days and is higher than that of 3&7
days.
3. Average split tensile strength value is 0.936 N/mm2
for 28days and is higher than that of 3&7 days.
4. At the age of 3days, average flexure strength value was 0.66 N/mm2
and 1.19 N/mm2
for 28 days.
5. Results were obtained indicated that with the activator ratio 1:3, the strengths were maximum than
that of 1:2&1:2.5.
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