This paper presents a laboratory investigation on optimum level of Fly ash and Ground Granulated Blast Furnace Slag (GGBS) as a partial replacement of cement to study the strength characteristics of concrete. Portland cement was partially replaced by 5%, 6%, 7%, 8%, 9%, 10% of GGBS and Fly ash by 20%, 40%, 60% respectively. The water to cementations materials ratio was maintained at 0.45 for all mixes. The strength characteristics of the concrete were evaluated by conducting Compressive strength test, Splitting Tensile strength test and Flexural strength test. The compression strength test were conducted for 7days and 28days of curing and split tensile strength test and flexural strength test were conducted for 28days of curing on a M25 grade concrete. The mix proportion M25 was found to be 1:1.36:2.71.The test results proved that the compressive strength, split tensile strength and flexural strength of concrete mixtures containing GGBS and Fly ash increases as the amount of GGBS and Fly ash increase. After an optimum point, at around 9% of GGBS and 40% of Fly ash of the total binder content, the further addition of GGBS and fly ash does not improve the compressive strength, split tensile strength and flexural strength.

1. IJSRD - International Journal for Scientific Research & Development| Vol. 2, Issue 07, 2014 | ISSN (online): 2321-0613
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Experimental Study on Partial Replacement of Cement by Flyash and
GGBS
Syed Asif Ali1
Professor Shaik Abdullah2
1
P.G Student (Structural Engineering) 2
Professor
1,2
Department of Civil Engineering
1,2
K.B.N Engineering College, Gulbarga, Karnataka, India
Abstract— This paper presents a laboratory investigation on
optimum level of Fly ash and Ground Granulated Blast
Furnace Slag (GGBS) as a partial replacement of cement to
study the strength characteristics of concrete. Portland
cement was partially replaced by 5%, 6%, 7%, 8%, 9%,
10% of GGBS and Fly ash by 20%, 40%, 60% respectively.
The water to cementations materials ratio was maintained at
0.45 for all mixes. The strength characteristics of the
concrete were evaluated by conducting Compressive
strength test, Splitting Tensile strength test and Flexural
strength test. The compression strength test were conducted
for 7days and 28days of curing and split tensile strength test
and flexural strength test were conducted for 28days of
curing on a M25 grade concrete. The mix proportion M25 was
found to be 1:1.36:2.71.The test results proved that the
compressive strength, split tensile strength and flexural
strength of concrete mixtures containing GGBS and Fly ash
increases as the amount of GGBS and Fly ash increase.
After an optimum point, at around 9% of GGBS and 40% of
Fly ash of the total binder content, the further addition of
GGBS and fly ash does not improve the compressive
strength, split tensile strength and flexural strength.
Key words: GGBS, Fly ash, concrete.
I. INTRODUCTION
Concrete is a strong and durable material that has been
utilized since 19th
century. It is understood that many of the
early structures are deteriorating or have already
deteriorated away, however with the knowledge of the
material properties of concrete that is available, it is hard to
imagine that concrete structures is prematurely failing
before their intended service life. There are many factors
involved in these failures, some of which are due to
environmental conditions and others, which have arisen
from human errors or lack of knowledge. These are
controllable human factors that must be minimized in order
to have concrete perform for the duration of its intended
services life. Early age properties of concrete are vital to its
long-term performance. Many engineers are interested on
the strength of concrete in 28 days that they overlook the
importance of other early age issue especially when the mix
design has water to cementitious material ratio (w/c) lower
than 0.42. It has shown that for complete hydration of the
cement, the w/c ratio should be 0.42 and above. As the w/c
ratio decreases below 0.42, the cement undergoes self-
desiccation which leads to autogenously shrinkage. Concrete
is generally classified as Normal Strength Concrete (NSC),
High Strength Concrete (HSC) and Ultra High Strength
Concrete (UHSC). There is no clear cut boundary for the
above classification. Indian Standard Recommended
Methods of Mix Design denotes the boundary of 35 Mpa
between NSC and HSC. They did not talk about UHSC. But
elsewhere in the international forum, about thirty years ago,
the high strength label was applied to concrete having
strength above 40 Mpa. More recently, the threshold rose to
55 Mpa as per IS 456-2000.
II. LITERATURE REVIEW
A. Swamy. et.al. (1983):
Extensive investigations have been carried out by Swamy et.
al.(1983) on the properties in the fresh and hardened state of
Fly ash concrete containing normal weight and light weight
aggregate suitable for structural application. The mixes were
proportioned to have one-day strength comparable with
concrete without Fly ash, possessing adequate cohesiveness
and workability to enable them to be compacted into place
easily in structural members. The authors have after
conducting extensive tests on reinforced concrete structural
members with Fly ash and without Fly ash concluded that
reinforced Fly ash concrete in beams and slabs exhibit
structural performance similar to that of conventional
concrete with adequate safety factor and predicted by
existing codes. The authors have concluded on the basis of
the data presented with Fly ash of controlled quality,
structural concrete constructions can be designed to
incorporate Fly ash up to 30 percent by weight of cement
and that Fly ash concrete characteristic were in no way
different from these of comparable normal concrete.[1]
B. Anand Kumar B .G. (2012):
The best way to dispose any waste material (fly ash) is to
use it as one or the other forms like construction material.
In developed countries electrostatic precipitators collects fly
ash, which leads to greater fineness. Hence it shows good
pozzolonic activity. So it can be used as part replacement of
cement. The effective utilization of fly ash in any field is
possible only when a study of physical, chemical and
mineralogical properties of the particular fly ash available is
done. The properties will vary from plant to plant and with
in a plant the source of collection. It was decided to use the
fly ash of Raichur thermal power station in Karnataka in the
present work. With the study on the strength development
on various high volume fly ash concrete ( with at least 50 %
fly ash as binder) mixes, the following conclusions can be
drawn.
 High volume fly ash concrete can be developed
using GGBS upto 70% of fly ash as binder.
 As the GGBS content increases the workability
reduces at the same water containing and w/c.
 With a combination of 70% fly ash 10 % of GGBS
and remaining quantity of binder compressive
 Strength of 15MPa can be achieved.
 The cost of concrete may reduce up to 20% for high
strength concrete, and about 45 % for lower
 Strength concrete.[2]

2. Experimental Study on Partial Replacement of Cement by Flyash and GGBS
(IJSRD/Vol. 2/Issue 07/2014/068)
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III. MATERIAL AND ITS PROPERTIES
A. Cement:
Cement in general can be defined as a material which
possesses very good adhesive and cohesive properties which
make it possible to bond with other materials to form
compact mass. Locally available Ordinary Portland cement
of 53 grade of the ACC cement Branch conforming to ISI
standards has been procured, and following tests have been
carried out according IS:8112-1989. The Chemical
Compositions and Physical properties of OPC are shown in
table 1 & 2.
Table 1: Chemical Compositions (%) of OPC
Table 2: Physical properties of OPC
B. Fine Aggregates (F.A):
Locally available river sand which is free from organic
impurities is used. Sand passing through sieve is 4.75mm
and retaining on IS sieve 150µ is used in the investigation.
Care shall be taken to ensure that the sieves are clean before
use. (IS: 2386 (Part-I) – 1963). Physical Properties of Fine
Aggregate as shown in Table 3.
Fineness Modulus 3.1
Specific Gravity 2.76
Bulk Density
i) Loose 14.67kN/m3
ii) Compacted 16.50kN/m3
Grading Zone-II
Table 3: Physical Properties of Fine Aggregate
C. Coarse Aggregate:
The coarse aggregate used here with having maximum size
is 20mm. We used the IS 383:1970 to find out the
proportion of mix of coarse aggregate, with 60% 10mm size
and 40% 20mm. Physical Properties of Coarse Aggregate as
shown in Table 4.
Specific Gravity 2.62
Fineness Modulus 4.01
Bulk Density
I) Loose 13.43kn/M3
Ii) Compacted 16.45kn/M3
Water Absorption 0.73%
Flakiness Index 15.23
Elongation Index 20.85
Crushing Value 2.36
Impact Value 14.2
Table 4: Physical Properties of Coarse Aggregate
D. Fly ash:
It is most commonly used as a pozzolan in PCC
applications. Pozzolans are siliceous or siliceous and
aluminous material, which in a finely divided form and in
the presence of water, react with calcium hydroxide at
ordinary temperatures to produce cementitious compounds.
Particle size of fly ash varies from 1µm to 100µm in
diameter with more than 50% under 20µm.
E. Fly Ash in Portland Cement Concrete:
Fly ash can be used in portland cement concrete to enhance
the performance of the concrete. Portland cement is
manufactured with calcium oxide (CaO), some of which is
released in a free state during hydration. As much as 20
pounds of free lime is released during hydration of 100
pounds of cement. The Chemical Composition (%) and
Physical Properties of FLYASH as shown in Table 5 & 6.
Table 5: Chemical Composition (%) of FLYASH
Physical Form Off White Powder
Specific Gravity 2.78
Specific Surface area 400-600 m2/Kg
Bulk Density(Loose) 1000-1100 Kg/m3
Bulk Density (vibrate) 1200-1300 Kg/m4
Table 6: Physical Properties of FLYASH
F. Ground Granulated Blast Furnace Slag (GGBS):
Ground-granulated blast-furnace slag (GGBS or GGBFS) is
obtained by quenching molten iron slag (a by-product of
iron and steel-making) from a blast furnace in water or
steam, to produce a glassy, granular product that is then
dried and ground into a fine powder. The Chemical
Composition (%) of Ground Granulated Blast Furnace Slag
(GGBS) and Physical Properties of Ground Granulated Blast
Furnace Slag (GGBS) as shown in Table 7& 8.
Table 7: Chemical Composition (%) of Ground Granulated
Blast Furnace Slag (GGBS)
Table 8: Physical Properties of Ground Granulated Blast
Furnace Slag (GGBS)
6.19
2.45
3.55
60.29
18.24
2.38
Loss on Ignition 4
Al2O3
Fe2O3
MgO
CaO
SiO2
SO3
303 m2
/Kg
3.1
Soundness (Le-Chatlier Exp.) 10mm
Comp. Strength -7 days 51.6 MPa
Comp. Strength -28 days 71.3 MPa
50 min
275 min
Fineness (Sp. Surface)
Specific Gravity
Initial Setting Time
Final setting Time
60.5
30.8
3.6
1.4
0.91
0.14
1.1
0.8
MgO
SO3
K2O+Na2O
Loss on Ignition
SiO2
Al2O3
Fe2O3
CaO
34.26
17.11
1.23
35.17
6.41
1.72
0.3
0.15
SiO2
Al2O3
Fe2O3
CaO
MgO
SO3
K2O
Loss on Ignition
Off White PowderPhysical Form
Specific Gravity
Bulk Density (vibrate) 1200-1300 Kg/m4
2.78
Specific Surface area 400-600 m2/Kg
Bulk Density(Loose) 1000-1100 Kg/m3

3. Experimental Study on Partial Replacement of Cement by Flyash and GGBS
(IJSRD/Vol. 2/Issue 07/2014/068)
All rights reserved by www.ijsrd.com 306
G. Water (IS: 456-2000):
Water used for mixing and curing is clean and free from
injurious amount of oils, acids, alkalis, salts, sugar, organic
materials or other substances that may be deleterious to
concrete. Potable water is used for mixing concrete.
H. Casting and Curing of Control Specimen:
For each mix three cubes of 150mm x 150mm x 150mmin
size, three cylinders of 150mm diameter and 300m height,
three prisms of 100mm x 100mm x 500mm, were cast using
steel moulds. The caste specimens were kept in ambient
temperature for 24 hours. After 24 hours they were
demoulded and placed in water for curing. Cubes are used to
determine the compressive strength of concrete for 7 days
and 28 days. Three cylinders were used to determine the
split tensile strength of concrete for 28 days. Three prisms
were used to determine the Flexural strength of concrete
for 28 days by two point bending test with a supporting
span, using universal testing machine of capacity 1000kN.
I. Mix proportion per cubic meter of concrete
Water Cement Fine agg Coarse agg
191.6 lts 425.78 Kg 575.22 Kg 1160.7Kg
0.45 1 1.36 2.71
IV. RESULTS & DISCUSSION
A. Tests on Fresh Concrete
1) Workability Characteristics
 Slump Cone Test: The slump cone is cleaned and
the inside surface of the cone is oiled thoroughly. It
is then placed on a level surface and placing the
slump cone inside the sheet metal cylindrical pot of
the consistometer. The concrete is then filled into
the cone in four layers. Each layer is tamped 25
times with standard 16 mm tamping rod. After
filling the cone completely, the initial height of the
cone is noted, and then the cone is lifted without
disturbing it. Final reading corresponding to the
decrease in height of the centre of the slumped
concrete is noted down.
 Compaction Factor Test: The degree of
compaction, called the compaction factor, is
measured by the density ratio i.e., the ratio of the
density actually achieved in the test to the density
of the same concrete fully compacted. Results
shown in table 9.
Description of
Workability
Compaction
factor
Corresponding
slump mm
Very low 0.78 0.95
Low 0.85 25-50
Medium 0.92 50-100
High 0.95 100-175
Table 9: Results of Slump Cone Test and Compaction
Factor Test
B. Tests on Hardened Concrete
 Tests for Compressive Strength: The compressive
strength of concrete for cubes, all mixes at 7 and 28
days of curing is presented in table 10. Only 3
cubes were casted for various percentage
replacements of cement by FA and GGBS. The
result shows that the Compressive strength
increased with addition of fly ash up to 40% and
GGBS up to 9% replace by weight of cement and
further any addition of FA and GGBS the
compressive strength decreases. The initial strength
gradually decreases from 60% FA and GGBS 10%.
At 40% and 9% there is 28% increase in initial
compressive strength for 7 days and there is 24%
increase in initial compressive strength for 28 days.
It is represented in Figure 1 which shows the
Comparison and Effect of curing on compressive
strength of M25 Grade.
 Tests for split tensile strength: The split tensile
strength of concrete for cylinders, all mixes at 28
days of curing is presented in table 11. Only 3
cylinders were casted for various percentage
replacements of cement by FA and GGBS. The
Split Tensile strength of Cylinders are increased
with addition of fly ash up to 40% and GGBS up to
9% replace by weight of cement and further any
addition of FA and GGBS the Split Tensile
strength decreases. At 40% and 9% there is 25%
increase in initial split tensile strength for 28 days.
It is represented in Figure 2 which shows the Effect
of curing on split tensile strength of M25Grade .
 Tests for Flexural Strength: The flexural strength of
concrete for prisms, all mixes at 28 days of curing
is presented in table 12. Only 3 prisms were casted
for various percentage replacements of cement by
FA and GGBS. The flexure strength of prisms are
increased with addition of fly ash up to 40% and
GGBS up to 9% replace by weight of cement and
further any addition of FA and GGBS the flexural
strength decreases. At 40% and 9% there is 18%
increase in initial flexure strength. It is represented
in Figure 3 which shows the Effect of curing on
Flexural strength of M25 Grade.
Ggbs Flyash
Average In N/Mm2
7 Days 28 Days
0 0 23.0367 33.88
5 20 23.766 34.78
6 20 24.55 35.756
7 20 25.57 37.427
8 20 26.727 38.73
9 20 27.003 39.516
10 20 27.43 40.35
5 40 28.553 41.583
6 40 27.373 42.567
7 40 30.38 44.037
8 40 30.62 44.817
9 40 31.593 45.143
10 40 30.513 44.227
5 60 29.103 42.18
6 60 28.147 40.793
7 60 27.647 39.88
8 60 26.193 38.337
9 60 25.653 37.367
10 60 24.45 35.96
Table10:- Compressive strength test results for M25grade in
N/mm2

4. Experimental Study on Partial Replacement of Cement by Flyash and GGBS
(IJSRD/Vol. 2/Issue 07/2014/068)
All rights reserved by www.ijsrd.com 307
Fig 1: Comparison of compressive strength test for 7 & 28
days of curing
GGBS FLYASH AVERAGE
0 0 7.22
5 20 7.46
6 20 7.583
7 20 7.653
8 20 7.7
9 20 7.88
10 20 8.153
5 40 8.273
6 40 8.34
7 40 8.516
8 40 8.666
9 40 8.813
10 40 8.69
5 60 8.67
6 60 8.37
7 60 8.233
8 60 8.157
9 60 8.147
10 60 8.04
Table 11: Split Tensile Strength test results for M25 grade in
N/mm2
Fig 2: Split tensile strength test for 28 days of curing.
GGBS FLYASH AVERAGE
0 0 9.587
5 20 10.14
6 20 10.44
7 20 10.723
8 20 11.29
9 20 11.403
10 20 11.533
0
10
20
30
40
50
5 6 7 8 9 10
compressivestrengthinN/mm2
GGBS content (%)
compressive strength for M25
at 40% fly ash
7 days
28 days
0
20
40
60
0 5 6 7 8 9 10
compressivestrengthinN/mm2
GGBS content (%)
compressive strength for M25
at 20% fly ash
7 days
28 days
0
10
20
30
40
50
5 6 7 8 9 10
CompressivestrengthinN/mm2
GGBS content (%)
Compressive strength for
M25 at 60% fly ash
7 days
28 days
11
11.5
12
12.5
13
5 6 7 8 9 10
TensilestrengthinN/mm2
GGBS content (%)
Split tensile strength for M25
at 20% fly ash
28…
11
11.5
12
12.5
13
5 6 7 8 9 10
TensilestrengthinN/mm2
GGBS content (%)
Split tensile strength for M25
at 40% fly ash
28 days
9
10
11
12
13
5 6 7 8 9 10
TensilestrengthinN/mm2
GGBS content (%)
Split tensile strength for M25
at 60% fly ash
28 days

5. Experimental Study on Partial Replacement of Cement by Flyash and GGBS
(IJSRD/Vol. 2/Issue 07/2014/068)
All rights reserved by www.ijsrd.com 308
5 40 11.743
6 40 11.923
7 40 12.397
8 40 12.567
9 40 12.783
10 40 12.513
5 60 12.363
6 60 12.173
7 60 11.773
8 60 11.696
9 60 11.146
10 60 10.49
Table 12: Flexural Strength test results forM25 grade in
N/mm2
Fig 3: Flexural strength test for 28 days of curing
V. CONCLUSION
 The Optimum percentage of GGBS and fly ash was
found to be 9% and 40% respectively.
 The Optimum value of compressive strength for
M25 grade at 9% of GGBS and 40% of fly ash as
partial replace of cement was found to be
31.59N/mm2 at 7 days of curing.
 The Optimum value of compressive strength for
M25 grade at 9% of GGBS and 40% of fly ash as
partial replace of cement was found to be 45.47
N/mm2 at 28 days of curing.
 The compressive strength increases as the
percentage of GGBS and fly ash increases as
partial replace of cement.
 The Optimum value of split tensile strength for
M25 grade at 9% of GGBS and 40% of fly ash as
partial replace of cement was found to be 12.78
N/mm2 at 28 days of curing.
 The Optimum value of flexural strength for M25
grade at 9% of GGBS and 40% of fly ash as partial
replace of cement was found to be 8.81 N/mm2 at
28 days of curing.
REFERENCES
[1] Swamy R.N and Sami.A.R.Ali, Early Strength of
Fly ash Concrete for Structural Applications. ACI
Journal, October 1983, Vol.80, PP 414-423
[2] Anand Kumar B .G, effective utilization of fly ash
and supplementary cementitious material in
construction technology.IJACT,VOL.01,ISSUE-
2,2012
[3] IS 456: 2000, ―Indian Standard Code of Practice
for Plain and Reinforced Concrete‖, Bureau of
Indian Standard, New Delhi.
[4] IS 10262: 1982, ―Recommended Guidelines for
Concrete Mix design‖, Bureau of Indian Standard,
New Delhi.
[5] IS 383: 1970, ―Specification for Coarse aggregate
and Fine aggregate from Natural Sources for
Concrete‖, Bureau of Indian Standard, New Delhi.
[6] IS 5816: 1999, ―Spliting Tensile Strength of
Concrete Method of Test‖, Bureau of Indian
Standard, New Delhi.
[7] IS 516: 1959, ―Flexural Strength of Concrete‖,
Bureau of Indian Standard, New Delhi.
[8] IS 9399: 1959, ―Specification for Apparatus for
Flexural Testing of Concrete‖, Bureau of Indian
Standard, New Delhi.
6.5
7
7.5
8
8.5
0 5 6 7 8 9 10
FlexuralstrengthinN/mm2
GGBS content (%)
Flexural strength for M25 at 20%
fly ash
28 days
7.5
8
8.5
9
5 6 7 8 9 10
FlexuralstrengthinN/mm2
GGBS content (%)
Flexural strength for M25 at
60% fly ash
28 days
8
8.5
9
5 6 7 8 9 10
FlexuralstrengthinN/mm2
GGBS content (%)
Flexural strength for M25 at 40%
fly ash
28 days