a study on combination of steel and glass fibers...
TRANSCRIPT
© January 2017 | IJIRT | Volume 3 Issue 8 | ISSN: 2349-6002
IJIRT 144189 INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN TECHNOLOGY 35
A STUDY ON COMBINATION OF STEEL AND
GLASS FIBERS AS HYBRID FIBERS IN CONCRETE
N.N.Pavan Kumar1, T.Raja Shekar2, and P.Tejeswar Kumar3 1M.Tech Student, Jogaiah Institute of Technology and Science, Kalagampudi
2Head of the Department, Jogaiah Institute of Technology and Science, Kalagampudi 3Assistant Professor, Jogaiah Institute of Technology and Science, Kalagampudi
Abstract—Concrete is a brittle material when subjected
to normal stresses and impact loads, where tensile
strength is relatively low compared to compressive
strength. This can be improved by addition of fibrous
material. The geometric size and modulus of fibers are
the main factors influence the mechanical performance
of fiber reinforced concrete. The use of different type of
fibers in a suitable combination may potentially improve
the overall mechanical performance of concrete and
increase tensile strength, energy absorption capacity of
concrete. The present investigation studies the synergic
mechanical properties of hybrid fiber polymer
reinforced concrete. The properties of plain concrete,
mono steel fiber concrete, glass fiber concrete and hybrid
fiber concrete of M20 grade were studied and the
properties of hybrid fiber concrete are compared with
respect to plain and mono steel fiber and glass fiber
concrete. Similarly the axial stress-strain curves under
Axial Compression are studied.
Index Terms—Fiber, synergic mechanical properties,
hybrid fiber polymer, mono steel fiber and glass fiber
concrete
I. INTRODUCTION
Concrete is acknowledged to be a relatively brittle
material when subjected to normal stresses and impact
loads, where tensile strength is approximately just one
tenth of its compressive strength. As a result for these
characteristics, concrete flexural members cannot
support such loads that usually take place during their
service life. Historically, concrete came to be
reinforced with continuous reinforcing bars to
withstand tensile stresses and to compensate for the
lack of ductility and strength.
More energy is required for propagation of cracks into
the hardened cement paste than around the coarse
aggregate. Due to the sharpness of the cracks in the
concrete the rate of propagation of the cracks is higher
than ductile material. That is why the concrete
possesses lower strain level at failure. The propagation
of the crack in the concrete is perpendicular point to
the principal tensile stress acting at that point .This is
the case both in compression and tension. In the direct
tension, cracks open up in a plane perpendicular to the
direction the load applied. In the compression, the
cracks open up due to lateral strain which induces the
tensile stress. With increasing compressive stress, the
lateral strain increases and the energy gets dissipated
by the propagation of cracks creating new surfaces.
Then the failure takes place by splitting of the
concrete.
II. MATERIALS
A. Cement
The Cement used in the investigation was 53 Grade
Ordinary Portland cement confirming to IS:
12269[1987]. The cement was obtained from a single
consignment and was of the same grade and same
source. The specific gravity, standard consistency and
initial setting time are respectively 3.11, 33% and
35min.
B. Fine aggregate
The fine aggregate conforming to Zone-2 according to
IS: 383[1970] were used. The fine aggregate used was
obtained from a nearby river source. The bulk density,
specific gravity and fineness modulus of the sand used
were 1.41g/cc, 2.60 and 2.90.The sand obtained was
sieved as per IS sieves (i.e.2.36, 1.18,600,300 and
150mm). Sand retained on each sieve was filled in
different bags and stacked separately for use. To
obtain zone-2 sand correctly, sand retained on each
sieve was mixed in appropriate proportion in which
each size fraction
© January 2017 | IJIRT | Volume 3 Issue 8 | ISSN: 2349-6002
IJIRT 144189 INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN TECHNOLOGY 36
C. Coarse aggregate
Crushed granite Aggregate was used as coarse
aggregate. The coarse aggregate used was obtained
from a local crushing unit having 20mm normal size,
well graded aggregate according to IS: 383[1970]. The
bulk density, specific gravity and fineness modulus of
the coarse aggregate used were 1.46g/cc, 2.78 and 7.1
respectively. The coarse aggregate procured from
quarry was filled in bags and stacked separately.
D. Water
Potable water was used in the experimental work for
both mixing and curing.
E. Steel fibers
Initially, round steel fibers were produced by cutting
smooth high tensile steel wire of uniform cross
section; much of it rejected portions of the wire used
in steel belted radial lines. To improve the quite low
resistances to fiber pull out of smooth uniform fibers.
The object was to augment the adhesive bond by
introducing mechanical interlock between fiber and
matrix in the same way that deformed rebar improves
bond compared with smooth rebar. Keeping in view of
this above, fiber diameter is chosen to give raise the
desired aspect ratio. An Aspect ratio of 60 (0.5 mm
diameter and 30 mm length) is adopted. The properties
of steel fibers are shown in the table1
Table1. Physical and mechanical properties of steel
fibers
III. METHODOLOGY
In this study M20 Standard Grade of Concrete is being
used. Mix design is carried out as per IS: 10262(2009)
code stipulations and proportions corresponding to
M20 are arrived at as 1:1.5:3:0.6
IV. EXPERIMENTS ON HYBRID FIBER
REINFORCED CONCRETE
A. Fresh properties of hybrid fiber reinforced concrete
The fresh properties of hybrid fiber reinforced
concrete include measuring the workability of
concrete by slump cone test. For various proportions
of fiber content the slump values are noted. Slump test
is the most commonly used method of measuring
consistency of concrete which can be employed either
in the laboratory or at site work. The apparatus for
conducting the slump test essentially consists of a
metallic mould in the form of a frustum of a cone
having the internal dimensions as bottom diameter of
20cm, top diameter of 10cm and an height of
30cm.The slump cone is shown in fig1
Fig 1. Slump cone test
B. Hardened properties of hybrid fiber reinforced
concrete
1) Compressive strength
The cube specimens were tested in a standard
compression testing machine .The bearing surface of
the machine was wiped off clean and any loose sand
or other material removed from the surface of the
specimen . The axes of the specimens were carefully
aligned at the center of the loading frame. The load
applied was increased continuously at a constant rate
until the resistance of the specimen to the increasing
load breaks down and no longer can be sustained. The
maximum load applied on the specimen was recorded.
The rate of loading was adopted as per IS 516 [1956]
Fig 2.Cubes testing in universal testing machine for
compressive strength
2) Split tensile strength
The bearing surface of the casting was wiped clean, in
case of cylindrical specimens the test was carried out
Property Steel fibers
Length(l) 30mm
Diameter(d) 0.5mm
Aspect ratio(l/d) 60
Specific gravity 7.8
Tensile strength 1700 MPa
Elastic modulus 200 GPa
Failure strain 3.5%
© January 2017 | IJIRT | Volume 3 Issue 8 | ISSN: 2349-6002
IJIRT 144189 INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN TECHNOLOGY 37
by placing the specimen horizontally between the
loading surfaces of the compression testing machine
for split tensile strength and the axis of the specimen
was carefully aligned with center of the loading
frames. The load was applied and increased
continuously till the specimen breaks. The maximum
load was recorded. The test was performed as per IS
516 [1956]. By obtaining the failure load the split
tensile strength is calculated using the formulae
Split tensile strength = 2P/ (3.14DL)
Where, P = Failure load, D = Diameter of cylinder
And L = Length of cylinder
Fig 2.Cylinders testing in UTM to find split tensile
strength
3) Flexural tensile strength
The flexural strength of the specimen is expressed as
the modulus of the rupture. The method used in testing
is third point loading.. The strength in the bearing is
the extreme fiber stress on the tensile side at the point
of the failure. The test was performed as per IS 516
[1956]. If ‘a’ equals the distance between the line of
fracture and the nearer support, measured on the
centered line of the tensile side of the specimen, in cm,
is calculated to the nearest 0.05 MPa as follows
when ‘a’ is greater than 20.0
cm for 15 cm specimen or greater than 13.3 cm for a
10.0 cm specimen, or
When ‘a’ is less than
20.0 cm but greater than 17 cm for 15 cm specimen, or
less than 13.3 cm but greater than 11 cm for a 10 cm
specimen where
b = measured width in cm of the specimen,
d = measured depth cm of the specimen at the point of
the failure,
l = length in cm of the span on which the specimen
was supported, and
P =Max. Load in kg applied to the specimen.
If ‘a’ is less than 17 cm for a 15 cm specimen, or less
than 11 cm for a 10 cm specimen, the results of the test
be discarded.
Fig 3.Prisms testing for flexural strength
4) Testing for Stress-Strain Curve
The cured specimens are capped with plaster of Paris
before testing to provide a smooth loading surface.
The set up of two square frames along with the
compressometer is used for measuring the strains.
Tests are continued until the peak load dropped to
about 0.5 times the peak load. Beyond the peak load,
the strains increased at a rapid rate and are
accomplished with a decrease in the load carrying
capacity of the specimen.
Fig 4.Cylinders testing for stress-strain curve
Fig 5.Prisms testing in tensile testing machine for load-
deflection curves
© January 2017 | IJIRT | Volume 3 Issue 8 | ISSN: 2349-6002
IJIRT 144189 INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN TECHNOLOGY 38
V. RESULTS AND DISCUSSIONS
A. Compressive strength
Table 2.Compressive loading test results of plain
concrete
S.NO Load(KN) Compressive
strength (MPa)
1 610 27.11
2 625 27.77
3 645 28.66
Average 27.84
B. Split tensile strength
Table 3.Split tensile strength test results for plain
concrete
S.No Load(KN) Split tensile
strength
(MPa)
1 200 2.82
2 180 2.54
3 220 3.11
Average 2.82
C) Flexural strength
Table 4.Flexural strength test results for plain concrete
S.No Load(KN) Flexural
strength
(MPa)
1 6.76 3.38
2 6.81 3.40
3 7.10 3.55
Average 3.44
D) Hybrid fiber reinforced concrete
The hybrid fiber concrete is prepared with optimum
dosage of steel fiber concrete (1.0% by volume of
concrete) and varying the proportion of glass fibers
keeping SBR latex content constant as 2% by weight
of cement. Initially trial mixes were conducted with
various proportions and based on that the proportions
of glass fibers are 0.1%, 0.2%, 0.3%, 0.4% and 0.5%
by volume of concrete respectively. The various Mix
ID are AP- Plain AS- Steel fiber, AG- Glass fiber and
ASG- Steel and glass fiber
Table 5.Dosage of different fiber combinations used in
the study
Mix ID
Volume
fraction of steel
fibers
Volume
fraction of
glass fibers
(%) (%)
AS 1 0
AG 0 0.5
ASG 1 0.5
Bar chart 1: Comparison of compressive strength of
plain, mono steel fiber, glass fiber and hybrid fiber
concrete
Bar chart 2: Split tensile comparison between plain,
mono steel fiber, glass fiber and hybrid fiber
Bar chart 3: comparing flexural strength of plain, mono
steel fiber, Glass fiber and hybrid fiber concrete
27.84
30.529.4
33.03
24
26
28
30
32
34
AP AS AG ASG
Co
pre
ssiv
e S
tre
ngt
h in
M
Pa
compressive strength in MPa
0
1
2
3
4
5
AP AS AG ASG
Split
Te
nsi
le S
tre
ngt
h
inM
Pa
Split Tensile strength in MPa
0
1
2
3
4
5
6
AP AS AG ASG
Fle
xura
l Str
en
gth
in M
Pa
Flexural Strength in MPa
© January 2017 | IJIRT | Volume 3 Issue 8 | ISSN: 2349-6002
IJIRT 144189 INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN TECHNOLOGY 39
Graph1: Axial Stress -Strain for plain concrete
Graph 2: Axial Stress -Strain curve for Mono Steel
fiber Concrete
Graph 3: Axial Stress -Strain curve for Glass fiber
concrete
Graph 4: Axial Stress-Strain Curves comparing all
types of fiber concretes
VI. CONCLUSION
The following are the conclusions from the present
study
1. It is possible to produce hybrid fiber polymer
concrete composites using glass fibers in
combination with steel fibers with an
enhancement in the mechanical properties of
concrete, toughness and ductility of the concrete
2. The increase in the compressive strength, split
tensile strength and flexural strength of hybrid
fiber polymer concrete compared to plain
concrete are 25%, 45% and 41% respectively.
Similarly the percentage increase of
compressive, split tensile and flexural strength of
hybrid fiber compared to mono steel fiber are
1.4%, 25% and 15% respectively.
3. Increased fiber availability of glass fibers in
bridging smaller micro cracks could be the
reason for the enhancement in split and flexural
properties.
4. The post peak behavior mainly depends on the
steel fibers as the glass fibers are inability to
sustain high crack widths resulting at large
deflections.
5. There is enhancement in energy absorption
capacity due to addition of fibers and polymer
which indicates the increase in ductility of
concrete.
6. A major significance of these findings is that
steel fibers in concrete could be replaced to a
0
5
10
15
20
25
0 0.002 0.004
STR
ESS
in M
Pa
STRAIN
AP
0
10
20
30
0 0.002 0.004 0.006
Stre
ss in
MP
a
Strain
AS
0
5
10
15
20
25
0 0.002 0.004 0.006
Stre
ss in
MP
a
Strain
AG
-505
1015202530354045
0.0000 0.0020 0.0040 0.0060 0.0080
STR
ESS
in M
Pa
STRAIN
ASG AP-0% AS-1% AG-0.5%
Hybrid Fibers
© January 2017 | IJIRT | Volume 3 Issue 8 | ISSN: 2349-6002
IJIRT 144189 INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN TECHNOLOGY 40
small extent with glass to provide better
properties of the concrete.
7. Jogaiah Institute of Technology and Science,
Kalagampudi.
FUTURE SCOPE
1. The study can expand to Study of behavior of
hybrid fibers in self compacting concrete, high
strength, self compacting/curing and other
modern type of concretes to observe the influence
and improvement in the behavior of concrete in
terms of its energy absorption and fracture.
2. There is need to Study of hybrid fibers with latex
as polymer under torsion and shear.
3. The study of behavior of hybrid fiber polymer
concrete for high strength concretes
4. The study of different type of hybrid fiber
combinations like steel- glass fiber, steel-
polypropylene fiber with different types of
polymers.
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