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IJSART - Volume 1
Issue 4 –APRIL 2015
ISSN [ONLINE]: 2395-1052
Investigation Of Concrete Properties With Different
Types Of Fibers With Their Variation Of Volume
Fraction And Different Aspect Ratio
Mr. Charkha Kailas 1, Prof. Prashant Awsarmal2
1, 2
MIT Aurangabad
Abstract- The present work deals with the literature works of
different researcher’s results of their experimental
investigations on steel fiber reinforced concrete. Effect of
these different types of steel fibers on various strengths of
concrete are studied. They are use Fibers at various volume
fraction rates like as 0 % to 5 % by weight of cement. Various
strengths considered for investigation are compressive
strength, flexural strength, split tensile, and bond strength.
Results are observe of different researchers and their
experimental comparison of results of steel fiber reinforced
concrete with that of normal concrete showed the significant
improvements in the results of various strengths like as
compressive strength, flexure strength, splitting strength,
bonding strength of concrete with different types of steel fiber
with various constant volume fractions and different aspect
ratio.
Keywords- Concrete, Steel Fibers, Hook end, Crimped, Straight,
Compressive, Flexure, Split Tensile and Bond Strength.
metallic and non-metallic fibers. Here, we will mainly discuss
Steel Fiber Reinforced Concrete (SFRC). The SFRC is a
composite material made of cement, fine and coarse
aggregates and discontinuous discrete steel fibers. In tension
SFRC fails only after the steel fiber breaks or pulled out of the
cement matrix. The composite nature of SFRC is responsible
for its properties in freshly mixed and hardened state. The
SFRC possess many excellent dynamic performances such as
high resistance to explosion and penetration as compared to
traditional concrete. When used in structural applications,
SFRC should only be used in a supplementary role to inhibit
cracking, to improve resistance to impact or dynamic loading
and resist material disintegration.
The investigation reported in this paper is aimed at studying
the behavior of steel fiber reinforced concrete beam under
combined loading. The tests conducted on rectangular beams
under different combination. The results of tests will be
comparing with the theoretical predictions. A good agreement
between the theory and experiment will been observed.
I. INTRODUCTION
1.1 Objectives
Fiber Reinforced Concrete (FRC) is a composite
material made primarily from hydraulic cements, aggregates
and discrete reinforcing fibers. Fiber incorporation in concrete,
mortar and cement paste enhances many of the engineering
properties of these materials such as fracture toughness,
flexural strength, resistance to fatigue, impact, thermal shock
and spalling. It is a type of building material that is increasing
in use. New types of concrete develop continuously and the
need to update the knowledge on the use of fiber
reinforcement in such concrete increases. The use of fiber
reinforcement is not a particularly recent idea. During ancient
times, fibers extracted from organic material were used. Fiber
Reinforced Concrete started to come to its modern industrial
use during the 1960‟s. The first applications were mainly
defense related where FRC was used in various shelter
structures. Research development has led the FRC to increase
its use as a building material. Nowadays, it is commonly
applied in shotcrete, pavements, industrial floors, bridge decks
and precast elements.
The fiber reinforced concrete is produced using different types
of fibers. The fibers are mainly classified in two groups as
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The objective of this study is to investigate the
mechanical properties like as compressive strength, flexure
strength, splitting strength and bond strength of concrete with
different types of steel fiber with different volume fractions
and different aspect ratio.
II. LITERATURE REVIEW
2.1 Fiber Reinforced Concrete
Fiber reinforced concrete can be defined as a
composite material consisting of a cement matrix containing
uniformly or randomly dispersed discrete fibers. The fibers act
as crack arrestors that restrict the growth of cracks in the
matrix, controlling them from enlarging which under stress
eventually causes brittle failure.
In the past, attempts have been made to impart
improvement in tensile properties of concrete members by
way of using conventional reinforced steel bars and also by
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IJSART - Volume 1
Issue 4 –APRIL 2015
applying restraining techniques. Although both these methods
provide tensile strength to the concrete members, they
however, do not increase the inherent tensile strength of
concrete itself.
It has been recognized that the addition of small,
closely spaced and uniformly dispersed fibers to concrete
would act as crack arrester and would substantially improve its
static and dynamic properties. This type of concrete is known
as Fiber Reinforced Concrete. Fiber is a small piece of
reinforcing material possessing certain characteristic
properties. They can be circular or flat. The fiber is often
described by a convenient parameter called “aspect ratio”. The
aspect ratio of the Fiber is the ratio of its length to its
diameter. Typical aspect ratio ranges from 30 to 150.
Basically fibers are classified asmetallic fibers and polymeric
fibers. Different fibers give different effects such as follows:
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Metallic fibers:
Increase of fracture energy, which subsequently
improves ductility
Increase of strength such as compressive strength,
tensile strength, etc.
Reduction of tendency for cracking
Polymeric Fibers:
Decrease of microscopic crack growth with high
loading
Gain in fire resistance
Decrease of early shrinkage
Glass Fibers:
Decrease of early shrinkage
2.2 Classification of Fibers
Fig-2.1 Classification of Fibers
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MPa. The minimum strength specified in ASTM is 345 MPa.
The modulus of elasticity for metallic fiber is 200 GPa. The
fiber cross section may be circular, square, or irregular. The
length of the fiber is normally less than 75 mm even though
longer fibers have been used. The length-diameter ratio
typically ranges from 30 to 100 or more.
2.4 Polymeric fibers
Synthetic polymeric fibers have been produced as a
result of research and development in the petrochemical and
textile industries. Fiber types that have been tried with cement
matrices include acrylic, aramid, nylon, polyester,
polyethylene, and polypropylene. They all have a very high
tensile strength, but most of these fibers (except for aramid)
have a relatively low modulus of elasticity. The quality of
polymeric fibers that makes them useful in FRC is their very
high length-to-diameter ratios; their diameters are on the order
of micrometers. Polymeric fibers are available in single
filament or fibrillated form. The length used in FRC range
from 12 to 50 mm. The number of studies of FRC containing
polymeric fibers is very limited.
2.5 Basic Mechanism of Fiber Reinforcement
Fiber influences the mechanical properties of
concrete in all modes of failure, especially those that induce
fatigue and tensile stresses. The strengthening mechanism of
fibers involves transfer of stress from the matrix to the fiber by
interfacial shear or by interlock between the fiber and matrix.
With the increase in the applied load, stress is shared by the
fiber and the matrix. With the increase in the applied load,
stress is shared by the fiber and the matrix in tension until the
matrix cracks; then the total stress is progressively transferred
to the fibers, till the fibers are pulled out, or break, or break in
tension.
Fiber efficiency and the fiber content are the
important variables controlling the performance of FRC. Fiber
efficiency is controlled by the resistance to pullout, which
depends on the bond at the fiber matrix interface. Pullout
resistance increases with fiber length. Since pull out resistance
is proportional to the interfacial area, the smaller the diameter,
the larger is the interfacial area available for the bond. For a
given fiber length, smaller the area, more effective is the bond.
The composite effect of these two variables is expressed by
the „aspect ratio‟ (length/diameter). Fiber efficiency increases
with increase in „aspect ratio‟.
2.3 Metallic Fibers
Metallic fibers are made of either carbon steel or
stainless steel. The tensile strength ranges from 345 to 1380
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The contribution of fiber to the composite depends
upon the fiber material and type, Length (L), diameter (d), and
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IJSART - Volume 1
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aspect ratio (L/d), and volume concentration of fibers in the
matrix.
2.6 Factors Influencing Fiber Reinforced Concrete
Fiber reinforced concrete can be defined as a
composite material consisting of a cement-based matrix
containing an ordered or random distribution of fibers. The
fibers act as crack arrestors that restrict the growth of flaws in
the matrix, controlling them from enlarging under stress into
cracks which eventually cause failure. By inhibiting the
propagation of cracks originating from internal flaws,
considerable improvements in static and dynamic properties
can be obtained andfibers impart to the composite qualities of
crack control, toughness, ductility impact resistance.
The use of continuous, aligned fibers in a cement
matrix is fundamentally not different from conventional
reinforced or pre-stressed concrete, where the large diameter
reinforcing bars or the smaller diameter pre-stressing wires
behave analogously to the continuous aligned fibers. The
phenomena of multiple cracking and of composite action in
such materials have been well established for over a century.
Obviously the highest strength characteristics are obtained
when the fibers are aligned to resist the critical stresses, but
then the material becomes markedly anisotropic.
A more exciting challenge that will find a wider
practical application is the use of short, discontinuous fibers
that are uniformly in the matrix. It is true that with random
orientation not all fibers are equally effective in crack control
or in their strengthening and stiffening role: nevertheless, if
sufficient strength and crack control improvements could be
obtained, the practical advantages of discontinuous fibers will
outweigh the strength advantage of continuous aligned fibers.
The effective reinforcement of the matrix and the efficient
transfer of stress between the matrix and the fiber depend
upon many factors. Many of these factors are intimately
interdependent, and exercise a profound but complex
influence on the properties of the composite.
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The relative fiber matrix stiffness
Fiber matrix interfacial bond
Strain compatibility between fiber and the matrix.
Shape of fibers
Strength of fibers
Fiber orientation
Specimen size
Span of specimen
Spacing of fibers
Physical and mechanical properties of fibers
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2.7 Steel Fiber Reinforced Concrete
Steel fiber reinforced concrete is a composite
material made of hydraulic cements, fine and coarse
aggregate, and a dispersion of discontinuous, small steel
fibers. It may also contain pozzolans and admixtures
commonly used with conventional concrete. The addition of
steel fibers significantly improves many of the engineering
properties of mortar and concrete, mainly impact strength and
toughness. Flexural strength, fatigue strength, and the ability
to resist cracking and spalling are also enhanced. Similarly,
addition of fibers decreases the workability of fresh concrete
and this effect is more pronounced for fibers with high aspect
ratios. Research and design of steel fiber reinforced concrete
began to increase in importance in the 1970s, and since those
days various types of steel fibers have been developed. They
differ in material as well as in size, shape and surface
structure, as shown in figure 2.1. Due to different
manufacturing processes and different materials, there are
differences in the mechanical properties such as tensile
strength, grade of mechanical anchorage and capability of
stress distribution and absorption.
Figure 2.2: Different Types of Steel Fibers
There are drawn wire fibers, cut sheet metal fibers
and milled steel fibers. Melt extracted fibers are amorphous
and thus stainless. In order to improve anchorage and
adhesion with the concrete matrix, the shape can be
designed with hooked ends, completely corrugated or
provided with end cones. Steel fibers are generally 12.7 - 63.5
mm long, and 0.45 - 1.0 mm in diameter. The usual amount of
steel fibers ranges from 0.25% to 2% by volume, or 20 - 157
kg/m¬¬3.
A lot of research work has been done and is going on the use
of different types of steel fibers in enhancing different
properties of concrete. Research work done by different
researchers is discussed here in brief.
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2.8 Research work by different researchers
Banthia and Sappakittipakorn: In the opinion of these
two researchers, crimped steel fibers with large diameters are
often used in concrete as reinforcement. Such large diameter
fibers are inexpensive, disperse easily and do not unduly
reduce the workability of concrete. However, due to their large
diameters, such fibers also tend to be inefficient and the
toughness of the resulting fiber reinforced concrete (FRC)
tends to be low. Hence, an experimental program was carried
out to investigate if the toughness of FRC with large diameter
crimped fibers can be enhanced by hybridization with smaller
diameter crimped fibers while maintaining workability, fiber
dispensability and low cost. The results showed that such
hybridization, replacing a portion of the large diameter
crimped fibers with smaller diameter crimped fibers can
significantly enhance toughness. The results also suggested
that such hybrid FRCs fail to reach the toughness levels
demonstrated by the smaller diameter fibers alone.
Bayramov, C. Tasdemir and M. Tasdemir: conducted
this research to optimize the fracture parameters of steel fiber
reinforced concretes to obtain a more ductile behavior than
that of plain concrete. The effects of the aspect ratio (L/d )
and volume fraction of steel fiber (Vf ) on fracture
properties of concrete in bending were investigated by
measuring the fracture energy (GF ) and characteristic
length (lch ). For optimization, three-level full factorial
experimental design and response surface method were used.
The results show that the effects of fiber volume fraction and
aspect ratio on fracture energy and characteristic length are
very significant.
Padmarajaiah and Ramaswamy ; carried out an
experimental program for eight fully prestressed beams and
seven partially prestressed beams made with high strength
fiber-reinforced concrete (plain concrete strength of 65 MPa).
These studies mainly attempted to determine the influence of
trough-shaped steel fibers in altering the flexural strength
at first crack and ultimate, the load–deflection and
moment–curvature characteristics, ductility and energy
absorption capacity of the beams. The magnitude of the
prestress, volume fraction of the fibers ranging from 0% to
1.5% and the location of fibers were the variables in the test
program. Analytical models to determine the load–
deflection and moment–curvature relationships as a
function of the fiber volume fraction were formulated.
Empirical relationships for the ultimate strength, first crack
load level, load versus deflection and moment versus
curvature as a function of fiber content were proposed by
making use of force equilibrium and compatibility
considerations. A primary finding was that the placement of
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ISSN [ONLINE]: 2395-1052
fibers over a partial depth in the tensile side of the prestressed
flexural structural members provided equivalent flexural
capacity as in a beam having the same amount of fiber over
the full cross-section. In large scale precast concrete
applications it is expected that this would be economical and
lead to considerable cost saving in the design without
sacrificing on the desired structural performance. The
analytical models proposed in this study predicted the test
results closely.
Rao and SeshuRelatively little research work has
been done on the behavioral aspects of SFRC under pure
torsion compared to its behavior under flexure or shear or
under combined loading. The researchers suggested that the
enhanced properties of SFRC in particular the ductility of
the matrix can be achieved when a minimum volume
fraction of fiber content is maintained. They studied the
behavioral aspects of plain SFRC members under pure torsion
and derived an empirical formula to predict the ultimate
torsional strength of the SFRC members under pure torsion.
Wang, Liu and Shen: investigated three types of SRFC
specimens with 0.0%, 3.0% and 6.0% (percentage by volume)
of ultra short steel fibers subjected to impact compression tests
conducted on 74-mm-diameter split Hopkinson pressure bar
(SHPB). Based on the stress–strain curves of different strainrates, as well as the random statistical distribution hypothesis
for SFRC strength, a dynamic damage constitutive model of
SFRC composite under compression was proposed. It was
established that both the volume fraction of steel-fiber and
strain-rate of loading exert significant influences on the SFRC
strength. The theoretical results were in good agreement with
experimental data.
Kurugo, Tanacan and Ersoy : studied the effect of
steel fiber reinforcement and polymer modification on the
Young‟s modulus of lightweight concrete aggregates. Through
experimental measurements, composite property models that
best describe the mixtures in terms of the properties and
volume fractions of their constituents were identified. The
relationship between various composite properties and the
mixtures used to produce the lightweight concrete were also
explored qualitatively.
Yazici, Inan and Tabak: investigated the effects of
aspect ratio (l/d) and volume fraction (Vf) of steel fiber on the
compressive strength, split tensile strength, flexural strength
and ultrasonic pulse velocity on steel fiber reinforced concrete
(SFRC). For this purpose, hooked-end bundled steel fibers
with three different l/d ratios of 45, 65 and 80 were used.
Three different fiber volumes were added to concrete mixes at
0.5%, 1.0% and 1.5% by volume of concrete. Ten different
concrete mixes were prepared. After 28 days of curing,
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compressive, split and flexural strength as well as ultrasonic
pulse velocity were determined. It was found that, inclusion of
steel fibers significantly affect the split tensile and flexural
strength of concrete in accordance with l/d ratio and Vf.
Besides, mathematical expressions were developed to estimate
the compressive, flexural and split tensile strength of SFRCs
regarding l/d ratio and Vf of steel fibers.
Mohammadi, Singh and Kaushik: studied properties
of plain concrete and steel fiber rein- forced concrete (SFRC)
containing fibers of mixed aspect ratio. An experimental
programme was planned in which various tests such as
inverted cone time, Vebe time and compaction factor were
conducted to investigate the properties of plain concrete and
fiber reinforced concrete in the fresh state. Compressive
strength, split tensile and static flexural strength tests were
conducted to investigate the properties of concrete in the
hardened state. The specimen incorporated three different
volume fractions, i.e., 1.0%, 1.5% and 2.0% of corrugated
steel fibers and each volume fraction incorporated mixed steel
fibers of size 0.6 • 2.0 • 25 mm and 0.6 • 2.0 • 50 mm in
different proportions by weight. Complete load deflection
curves under static flexural loads were obtained and the
flexural toughness indices were obtained by ASTM C-1018 as
well as JCI method. A fiber combination of 65% 50 mm +
35% 25 mm long fibers can be adjudged as the most
appropriate combination to be employed in SFRC for
compressive strength, split tensile strength and flexural
strength. They found better workability as the percentage of
shorter fibers increased in the concrete mix.
Song, Wu, Hwang and Sheu:
studied impact
resistance variations of high-strength steel fiber-reinforced
concrete (HSFRC), versus those of high-strength concrete
(HSC). They found that impact resistance of the high-strength
steel fiber-reinforced concrete improved satisfactorily over
that of the high-strength concrete; the failure strength
improved most, followed by first-crack strength and
percentage increase in the number of post- first-crack blows.
The two concretes resembled each other on the coefficient of
variation values, respectively, on the two strengths, whereas
the high-strength concrete was much higher in the value on the
percentage increase Lu and Hsu: conducted extensive
experimental program which showed the behavior of high
strength concrete and steel fiber reinforced high strength
concrete under uniaxial and triaxial compression. Triaxial
stress–strain relations and failure criteria were used to evaluate
the effect of steel fiber reinforcement on the mechanical
properties of high strength concrete in triaxial compression,
which were found to be insignificant.
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Lau and Anson: investigated the compressive
strength, flexural strength, elastic modulus and porosity of
concrete reinforced with 1% steel fiber (SFRC) and changes of
color to different elevated heating temperatures, ranging
between 105 °C and 1200 °C. The results showed a loss of
concrete strength with increased maximum heating
temperature and with increased initial saturation percentage
before firing. Mechanical strength results indicated that
SFRC performs better than non-SFRC for maximum
exposure temperatures below 1000 °C, even though the
residual strength remains very low for all mixes at this high
temperature. The variations with colour, which occurred, were
associated with maximum temperatures of exposure.
Altun, Haktanir and Ari : studied C20 and C30
classes of concrete produced each with addition of Dramix
RC-80/0.60-BN type of steel fibers (SFs) at dosages of 0
kg/m3, 30 kg/m3, 60 kg/m3, and their compressive strengths,
split tensile strength, moduli of elasticity and toughness were
measured. Nine reinforced concrete (RC) beams of 300 300
 2000 mm outer dimensions, designed as tension failure and
all having the same steel reinforcement, having SFs at dosages
of 0 kg/ m3, 30 kg/ m3, 60 kg/m3 with C20 class concrete,
and nine other RC beams of the same peculiarities with C30
class concrete again designed as tension failure and all having
the same reinforcement were produced and tested under
simple bending. The load versus mid-span deflection
relationships of all these RC and steel-fiber-added RC
(SFARC) beams under simple bending were recorded. First,
the mechanical properties of C20 and C30 classes of concrete
with no SFs and with SFs at dosages of 30 kg/ m3 and 60 kg/
m3 were determined in a comparative way. The flexural
behaviors and toughness of RC and SFARC beams for C20
and C30 classes of concrete were also determined in a
comparative way. The experimentally determined (midsection load)–(SFs dosage) and (toughness)–(SFs dosage)
relationships are given to reveal the quantitative effects of
concrete class and SFs dosage on these crucial properties.
2.9 Concluding remark
It is observed from the literature survey that the use
of steel fibers, especially hooked end fibers, crimped fiber and
straight fibers are more advantageous as they enhance the
overall mechanical properties of plain concrete than other
fibers. Thus, one can think of comparison in such steel fibers
by putting variation of volume fraction with their difference
aspect ratio, and check their engineering properties.
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III. EXPERIMENTAL WORK
Flow chart of experimental work:
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V. RECOMMENDATIONS FOR FUTURE WORK
The present work has good scope for future research,
some are given below:
1. Behaviour of concrete with different types of steel
fibers will be study by changing the volume fraction
also aspect ration
2. Check the strength of concrete by adding the Fly ash
in same work.
3. Investigation of strength of concrete with same work
by addition of Metacoline.
4. Finite Element Analysis.
5. Torsional Strength transfer mechanism in Circular
Section.
6. Study of resistant to chemical attack.
VI. APPLICATIONS
Steel Fiber Concrete is being used widely nowadays.
SFC has found number of applications, some of which are
listed below:
 Construction of highway paving and industrial
floors with crimped as well as strength fibers.
 Repairs and new construction on hydraulic
structures to provide resistance to cavitations and
severe erosion.
 Repairs and rehabilitation of marine structures.
 Tunnel as also as Cannel lining.
REFERENCES
IV. EXPECTED OUTCOME
From above study is conclude that, all mechanical
properties viz. compressive strength, flexure strength, splitting
strength and bond strength will be improved by addition of
fibers irrespective of fiber type and aspect ratio.
All strength likes compressive strength, flexure
strength and splitting strength will be improved with
increasing aspect ratio.
Also for same aspect ratio the hook ended fibrewill
be showing pronounce improvement in all properties of
concrete as compare crimped & straight fiber. There might be
decrease in the strength with decrease in aspect ratio of same
fiber type. The straight fibers will having less strength as
compared with hook end and crimped fibers. Also that will be
hook end and crimped fibers having because of their shape
and anchorage in the matrix resulting in more strength.
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