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EFFECT OF STEEL FIBERS ON FRESH AND HARDENED
PROPERTIES OF SELF COMPACTING CONCRETE
A SEMINAR REPORT
Submitted by
N. SIVA RAMA KRISHNA
Roll No: 141519
In partial fulfillment of seminar for the award of the
degree
Of
MASTER OF TECHNOLOGY
IN
ENGINEERING STRUCTURES
Under The Guidance of
Dr. S. Venkateswara Rao
Assistant Professor in Civil Engineering Department
NATIONAL INSTITUTE OF TECHNOLOGY
WARANGAL-506004
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NATIONAL INSTITUTE OF TECHNOLOGY
WARANGAL-506004
CERTIFICATE
This is certified that N. SIVA RAMA KRISHNA has submitted the
seminar report on
EFFECT OF STEEL FIBERS ON FRESH AND HARDENED PROPERTIES OF
SELF COMPACTING CONCRETE in the partial fulfillment of the 2nd
semester
M.Tech course in Engineering Structures as prescribed by the
National Institute of
Technology, Warangal during academic year 2015-2016 under my
supervision.
To the best of my knowledge the seminar report submitted by him
have not
been submitted to any university or institute for the award of
any degree.
Dr. S. Venkateswara Rao
Assistant professor
Department of Civil Engineering
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ACKNOWLEDGEMENTS
I deeply indebted to my guide Dr. S. Venkateswara Rao, Assistant
Professor in Department
of Civil Engineering, National Institute of Technology, Warangal
for his invaluable guidance,
motivation and constant encouragement throughout the course of
this seminar work. His help, advice
and guidance have been a constant source of inspiration to us
throughout the seminar course.
I will remain thankful to Mr. Sai Nitish and Mr. Praveen
research scholars in department of
civil engineering, NIT, Warangal for their support during this
seminar work.
I also thankful to all the faculty members of Civil Engineering
Department, NIT Warangal
who helped in this course of seminar.
Finally I express my gratitude to my parents for supporting me
in every walk of life.
N. Siva Rama Krishna
M.Tech, Engineering Structures
National Institute of Technology, Warangal
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ABSTRACT
Self-compacting concrete (SCC) is an innovative concrete that is
able to flow under its own weight,
completely filling formwork and achieving full compaction
without vibration. With the increase of
strength of concrete brittle ness of concrete increases, due to
which it will offer little resistance to
cracking which leads to sudden failure of the structure. Steel
fibers acts as a bridge to retard their
cracks propagation, and improve several hardened properties such
as tensile strength, toughness,
elastic modulus, energy absorption capacity etc...However,
addition of fibers to fresh concrete results
in a loss of workability. In this seminar the properties of
plain self-compacting concrete and self-
compacting concrete with steel fibers is studied. Slump flow,
J-ring and V-funnel tests were
conducted for evaluating the fluidity, filling ability and
segregation resistance of the fresh concrete.
Hardened properties of concrete such as compressive strength,
tensile strength and split tensile
strength are compared.
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CONTENTS
CHAPTER-1
INTRODUCTON
1.1 General
1.2 Advantages of Self Compacting Concrete
1.3 Indian scenario of SCC
CHAPTER-2
LITERATURE REVIEW
CHAPTER-3
EFNARC SPECIFICATIONS FOR SCC
CHAPTER-4
REVIEW OF JOURNAL PAPER
4.1 Materials
4.2 Mix proportions
4.3 Preparation and Casting of specimens
4.4 Results and Discussions
4.5 Conclusions
REFERENCES
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CHAPTER-1
INTRODUCTION
1.1 GENERAL
Self-compacting concrete (SCC) is considered as a concrete which
can be placed and compacted
under its self-weight with little or no vibration without
segregation or bleeding. It is used to facilitate
and ensure proper filling and good structural performance of
restricted areas and heavily reinforced
structural members [2]. The self-compactibility achieved not
only by high deformability of paste or
mortar, but also by resistance to segregation between coarse
aggregate and mortar when the concrete
flows through the confined zone of reinforcing bars. Okamura and
Ozawa have employed the
following methods to achieve self-compactibility:
Figure 1: Methods for achieving self-compactibility [1].
(1) Limited aggregate content
(2) Low water-powder ratio
(3) Use of super plasticizer
SCC was conceptualized in 1986 by Prof. Okamura at Ouchi
University, Japan [1]. SCC, like any
other concrete, is known to be brittle and can easily crack
under low levels of tensile force. This
inherent shortcoming, which limits the application of this
material, can be overcome by the inclusion
of fibers [3]. With addition of steel fibers, the energy
absorption capacity, toughness, flexural strength
and impact strength of concrete may increase significantly. But
workability of the concrete decreases
[4]. In this seminar addition of fly ash and steel fibers effect
on fresh and hardened properties self-
compacting concrete is presented.
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1.2 Advantages of Self compacting Concrete
Self-compacting concrete (SCC) is one of the very latest
developments in concrete technology. It is
boon to the construction industry. The SCC as the name suggests,
does not require to be vibrated to
achieve full compaction. This offers following advantages over
conventional concrete [13].
Improved durability of the concrete
Enhanced productivity
Improved surface finish
Enhancement in the flow ability
Faster construction time
Improvement of working environment
Higher resistance to segregation
Greater freedom in the design of complex geometries
Easier to place
Increased consumption of industrial waste products such as fly
ash
Improving the filling capacity of highly congested structural
members
Reduction in labor cost
1.3 Indian Scenario of SCC
In India, the development of concrete possessing self-compacting
properties is still very much in its
initial stages. Over the past couple of years, few attempts were
made using European Guidelines for
testing SCC in the laboratories and in the field. There are many
organization/academic
institutions/cement companies in India who are working hard in
the laboratory and field for the
advancement and use of SCC in structures to minimize carbon
emission and making cost effective
construction product [11].
SCC was used by Nuclear Power Corporation of India Ltd at
Tarapur, Kaiga and Rajasthan Atomic
Power Project. Some pioneering efforts have been made in Delhi
Metro Project. Laboratory studies
conducted at SERC Chennai, Indian Institute of Technology at
Madras and Roorkee have given
enough inputs and confidence to adopt SCC in India [12].
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CHAPTER-2
LITERATURE REVIEW
Nan Su, Kung-Chung Hsu and His-Wen Chai (2001) proposed a new
mix design method for self-
compacting concrete. First, the amount of aggregates required
was determined which is affected by
packing factor (PF), and the paste of binders was then filled
into the voids of aggregates to ensure that
the concrete thus obtained has flow ability, self-compacting
ability and other desired SCC properties.
The amount of aggregates, binders and mixing water, as well as
type and dosage of super plasticizer
to be used are the major factors influencing the properties of
SCC. Slump flow, V-funnel, L-flow, U-
box and compressive strength tests were carried out to examine
the performance of SCC, and the
results indicated that the proposed method could be used to
produce successfully SCC of high quality
[5].
Mustafa Sahmaran, Alperen Yurtseven, I. Ozgur Yaman (2005)
studied the hybrid fiber
reinforced self-compacting concrete. In which two different
types of steel fibers (straight and hooked)
with different aspect ratio used. Slump flow, V-funnel, and
J-ring tests are performed to assess
workability. Moreover, the mechanical properties, namely the
compressive and tensile strengths, and
the ultrasonic pulse velocities of hybrid fiber reinforced-SCC
mixtures are also determined at various
ages. It was observed that it is possible to achieve
self-compaction with considerable fiber inclusion
(60 kg/m3). Although results obtained from some of the mixes
exceeded the upper limits suggested
by EFNARC, all mixes had good flow ability and possessed
self-compaction characteristics [15].
Vinayak and Mangulkar (2013) investigated the flexural strength
of self-compacting concrete
specimen produced by silica fume, fly ash, metakaolin and steel
fibers. They used three types of steel
fibers such as wave steel fibers (WSF), Hook ended steel fibers
(HESF) and flat steel fibers (FSF)
with changing volume fraction of steel fibers from 0.5% to 4%.
Addition of silica fume, metakaolin
and fly ash into concrete were 2.5%, 2.5% and 10% by weight of
cement content respectively. The
flexural strength increases significantly due to the addition of
steel fibres compared with normal
concrete. In general, the flexural strength of the concrete
having Waving Steel Fibres (WSF) was
higher than that of concrete with Flat Steel Fibres (FSF) and
Hook Ended Steel Fibres (HESF) at the
same volume fractions of steel up to the limit. The increase is
up 3.5% volume fraction only beyond
this fraction flexural strength is decreasing. So optimum fiber
content is 3.5%. It is found that flexural
strength is most probably depends on amount of volume fraction
than that of type of fiber [14].
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Ponikiewski and Golaszewski (2013) studied the effect of
different type of steel fibers on rheological
properties, compressive strength, and flexure strength of
self-compacting concrete. Workability is
found out by conducting slum flow test, T50cm. By using two
point workability test they found the
rheological parameters yield stress and plastic viscosity. They
concluded that with increasing fiber
fraction rheological parameters are increasing. Decrease in
workability is small with the addition of
steel fibers in the range of 40-80 kg/m3, the property of self
compactibility is maintained. Beyond this
volume fraction of steel fibers workability is decreasing more
amount due to uneven distribution of
fibers. Load deflection curves are plotted from them we came to
know that energy absorption capacity
is increasing with addition of increasing fiber content [7].
S. Sable and K. Rathi (2012) aimed to determine and do the
comparative study of the properties of
concrete containing no fibers and concrete with fibers, as well
as the comparison on the effects of
different type and aspect ratio of fibers to the self-compacted
concrete. This investigation was carried
out using several tests, which included workability tests of
SCC, compressive test, indirect tensile test
and flexural test. Different steel fibers (crimped, straight and
hook ended) were used at different aspect
ratio (80, 50) with 2.5% volume fraction in making the concrete.
The investigation shows that it is
possible to achieve self-compaction with different types of
steel fiber with different aspect ratio [10].
Kamal,Safan,Etman and Kasem (2014) Studied the effect of
different fibers on the fresh and
hardened properties was studied. An experimental investigation
on the mechanical properties,
including compressive strength, flexural strength and impact
strength of fiber reinforced self-
compacting concrete was performed. The results of the
investigation showed that: the optimum
dosage of steel and polypropylene fiber was 0.75% and 1.0% of
the cement content, respectively. The
fibers they used are polypropylene fibers and steel fibers. They
concluded that Polypropylene fibers
have more impact resistance compared to steel fibers. And also
found that bleeding of fresh concrete
is decreased due to addition of fibers. The plain SCC specimens
failed suddenly in flexure and impact,
the counterpart specimens contain fibers failed in a ductile
manner, and failure was accompanied by
several cracks [8].
S.A. Bhalchandra and Amit Bajirao (2012) Aimed to study the
mechanical performance of plain
SCC and SFRSCC (Steel Fiber Reinforced Self Compacting Concrete)
by varying the different
volume fractions of steel fibers. They used the mineral
admixture of fly ash. Finally they found that
compressive strength is increasing with increasing fiber
content. Maximum compressive strength is
observed at 3% fiber content beyond that increment is marginal.
Flexural strength increase is 34.97%
over plain SCC [6].
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CHAPTER-3
EFNARC SPECIFICATIONS FOR SCC
A concrete mix can only be classified as Self Compacting
Concrete if the following three
characteristics are fulfilled.
Filling ability
Passing ability
Segregation resistance
Filling ability:
The ability of SCC to flow into and fill completely all spaces
within the formwork, under its own
weight.
Passing ability:
The ability of SCC to flow through tight openings such as spaces
between steel reinforcing bars
without segregation and blocking.
Segregation resistance:
The ability of SCC to remain homogeneous in composition during
transport and placing.
Many different test methods have been developed in attempts to
characterize the properties
of SCC. So far no single method or combination of methods has
achieved universal approval and
most of them have their adherents. Similarly no single method
has been found which characterizes all
the relevant workability aspects so each mix design should be
tested by more than one test method
for the different workability parameters [13]. List of some test
methods for different parameters of
SCC are shown in Table 1. Typical acceptance criteria for
Self-compacting Concrete with a maximum
aggregate size up to 20 mm are shown in Table 2.
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Table 1: List of test methods for workability properties of SCC
[13]
Table 2: Acceptance criteria for Self-compacting Concrete
[13]
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CHAPTER-4
REVIEW OF JOURNAL PAPER
This is the research done by S. Sable and K. Rathi [10]. The
objective of their study is to
determine and do the comparative study of the properties of
concrete containing no fibers and concrete
with fibers, as well as the comparison on the effects of
different type and aspect ratio of fibers to the
self-compacted concrete.
4.1 Materials
4.1.1 Cement:
The cement used in this experimental work is 53 grade Ordinary
Portland Cement which is confining
to IS 12269-1987. The specific gravity of the cement is 3.15.
The initial and final setting times were
found as 74minutes and 385 minutes respectively. Standard
consistency of cement was 30%.
4.1.2 Fine Aggregate:
The specific gravity of 2.75 and fineness modulus of 2.806 are
used as fine aggregate. The loose and
compacted bulk density values of sand are 1600 and 1688 kg/m3
respectively, the water absorption of
1.1%.
4.1.3 Coarse Aggregate:
Crushed granite aggregate with a maximum size of 12mm having the
specific gravity value of 2.70
and fineness modulus of 6.013 are used as coarse aggregate. The
loose and compacted bulk density
values of coarse aggregates are 1437 and 1526 kg/m3
respectively, the water absorption of 0.4%.
4.1.4 Fly Ash:
Fly ash used with the product name Pozzocrete60 which available
in 30 kg bags. It satisfies all the
requirements of the IS 3812: 1981.
4.1.5 Chemical Admixtures:
A polycarboxylic type super plasticizer (SP) is used in all
concrete mixtures with 1% dosage of weight
of cement. In addition to the SP, a viscosity modifying
admixture (VMA) is also used. Its dosage is
0.5% of weight of cement.
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4.1.6 Fiber:
The main variables used in the study are three different types
of steel fibers i.e. hook ended steel fiber
(HK), crimped type steel fiber(CR), straight type steel
fiber(SF) with two values of aspect ratios (80
and 50). 2.5 % constant dosages of fibers are used by weight of
cement.
4.2 Mix Proportions
The grade of the concrete produced is M30. Seven different types
of the concrete mixes are made
with 2.5%constant dosage of fibers by weight of cement. 30% of
the fly ash is replaced with cement.
The mix proportions are shown in Table 3.
Table 3 Mix Proportions [10]
S.NO Type
of
fiber
Aspect
ratio
Cement
(kg/m3)
Fly ash
(kg/m3)
Fine
Aggregate
(kg/m3)
Coarse
Aggregate
(kg/m3)
Water
(kg/m3)
SP
(%)
VMA
(%)
1. 0 0 498.3 0 903.916 737.484 203.306 1 0.5
2. HK
80/60
80 348.81 149.49 903.916 737.484 203.306 1 0.5
3. HK
50/30
50 348.81 149.49 903.916 737.484 203.306 1 0.5
4. SF
80/130
80 348.81 149.49 903.916 737.484 203.306 1 0.5
5. SF
50/80
50 348.81 149.49 903.916 737.484 203.306 1 0.5
6. CR
50/30
50 348.81 149.49 903.916 737.484 203.306 1 0.5
4.3 Preparation and Casting of specimens
The concrete cubes of size 150*150 are casted to find out the
compressive strength. The cylinders
with size 150mm diameter, 300 mm height are casted to evaluate
split strength of specimens. The
beams of 100*100*500 mm size are prepared to find out flexural
strength. After 24hrs of casting,
demoulded the specimens and kept in the specimens in curing
pond.
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4.4 Results and Discussion
4.4.1 Fresh Properties of SCC
In order to find out the fresh characteristics of Self
compacting concrete the tests like slump
flow, V-funnel, L-box, U-box and J-ring are conducted. The slump
flow is used to assess the
horizontal free flow when there is no restriction to the flow.
L-box and U-box are for the
evaluation of passing ability and J-ring test for stability
evaluation. The results of slump flow
and V-funnel tests are shown in Table 4. The test results of
L-box, U-box and J-ring are shown
in Table 5.
Table 4: Slump flow and V-funnel test results [10]
S. No
Type of fiber
Aspect
ratio
Slump flow
V-funnel test
Diameter of
flow (mm)
T50cm(sec)
Flow time
(Sec)
Flow
time at
T5min
(Sec)
1 0 0 715 2.89 7.20 9.02
2 HK 80/60 80 660 4.90 12.20 15.56
3 HK 50/30 50 690 4.30 10.30 12.34
4 SF 80/130 80 670 5.00 12.59 16.21
5 SF 50/30 50 700 4.70 11.23 13.39
6 CR 50/30 50 705 4.10 8.10 10.50
From the table 4 we can observe that slump flow diameter is in
the range of 660-715mm and
T50cm is 2.89-5 sec which are within the limits specified by the
EFNARC. V-funnel flow time
is in the range of 7.2-12.59 and V-funnel flow at T5min is
9.02-16.21. Expect two mixes HK
80/60 and SF 80/130 all other mixes satisfied the EFNARC
specifications. We can conclude
that the two mixes are having high viscosity.
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Table 5: The results of L-box, U-box and J-ring tests [10]
S. No Type of fiber Aspect ratio L-box
(h2/h1) ratio
U-box
H1-H2 (mm)
J-ring
H1-H2 (mm)
1 0 0 0.948 10 2
2 HK 80/60 80 0.821 27 7
3 HK 50/30 50 0.890 13 3
4 SF 80/130 80 0.858 30 6
5 SF 50/30 50 0.890 26 4
6 CR 50/30 50 0.898 12 4
The results of the L-box, U-box and J-ring in the range of
0.821-0.948, 10-30mm and 2-7 sec
respectively. The results are within the limits of EFNARC
specifications of SCC.
4.4.2 Hardened properties of SCC
The tests like compressive strength, split tensile strength and
flexural strength are conducted on the
hardened specimens of SCC. The results are shown in Table 6. The
variation of compressive strength,
split tensile strength and flexural strength shown in figure 2,
figure 3 and figure 4 respectively.
Table 6: Results of Compressive strength, Split tensile strength
and Flexural strength at 28
days [10]
S. No
Type of Fiber
Compressive Strength
(MPa)
Split tensile
strength
(MPa)
Flexural
Strength
(MPa) 7 Days 28 Days
1 0 23.39 32.50 3.82 4.98
2 HK 80/60 29.70 46.00 7.59 6.92
3 HK 50/30 24.66 43.96 6.85 5.97
4 SF 80/130 27.02 40.60 5.58 5.58
5 SF 50/30 23.11 36.60 4.68 5.18
6 CR 50/30 24.57 42.20 4.93 5.63
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Figure 2: Compressive strength at 28 days
From Figure 2, the compressive strength of HK 80/60 if more
compared to all other fibers.
For the same aspect ratio 50, HK fibers shows more strength and
SF shows lowest strength.
Figure 3: Split tensile strength at 28 days
From figure 3, the results shows that addition of fibers
increases the split tensile strength. HK 80/60
Shows maximum strength. For the same aspect ratio with different
fibers HK 50 having more split
tensile strength than CR 50 and SF 50.
0
5
10
15
20
25
30
35
40
45
50
0 HK 80/60 HK 50/30 SF 80/130 SF 50/30 CR 50/30
Co
mp
ress
ive
stre
ngt
h a
t 28
day
s
Type of fiber
Compressive Strength (MPa)
Compressive Strength (MPa)
0
1
2
3
4
5
6
7
8
0 HK 80/60 HK 50/30 SF 80/130 SF 50/30 CR 50/30
Split
ten
sile
str
engt
h
Type of fiber
Split tensile strength (MPa)
Split tensile strength (MPa)
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Figure 4: Flexural strength at 28 days
From figure 4, Flexural strength of HK 80/60 is compared to all
types of fibers. The maximum
percentage increase is 28.03%. The flexural strength of SF
fibers is lower than other two types of
fibers. Flexural strength is reduced in the same type of fiber
when aspect ratio is lowered.
4.5 Conclusions
It is possible to achieve self-compaction with the addition of
different steel fibers with
different aspect ratios. All mixes are having good flowing
ability.
With increasing aspect ratio viscosity of the concrete increases
which will leads to decrease
the ability to flow. Aspect ratio 80 havent satisfied the
V-funnel test results specified by the
EFNARC.
The SCC developed compressive strengths ranging from 32.50 to
46.00Mpa, Split tensile
strength ranges from 3.82 to 7.89MPa and Flexural strength
ranges from 4.98 to 6.92MPa at
the end of 28 days.
It is observed that for the same aspect ratio the hook ended
fiber shows improvement in all
properties of concrete as compared to the crimped & straight
fiber.
There is decrease in the strength with decrease in aspect ratio
of same fiber type.
The straight fibers have less strength as compared with hook end
and crimped fibers because
of their shape. Due to the shape, it is obvious that the hook
end and crimped fiber have good
bond and anchorage in the matrix resulting in more strength.
0
1
2
3
4
5
6
7
8
0 HK 80/60 HK 50/30 SF 80/130 SF 50/30 CR 50/30
Flex
ura
l Str
engt
h
Type of fiber
Flexural Strength (MPa)
Flexural Strength (MPa)
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REFERENCES:
1. Hajime Okamura and Masahiro Ouchi, Self Compacting Concrete,
Journal of Advanced
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relationships for steel fiber reinforced self-
compacting concrete, Structural Engineering and Mechanics Vol.
46, No. 2, 2013, pp 295-
322.
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the properties of self-compacting
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journal of emerging technology and advanced engineering Vol. 2,
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1799-1807.
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