EFFECT OF HYBRID FIBER WHEN
BLENDED WITH CONCRETE
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MOHIT VIDHATE
ADARSH SAWANT
CHETAN SAHANI
DINESH THAKUR
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CONTENT
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INTRODUCTION
DEFINATION OF HYBRID FIBER
TYPES OF FIBRE
PROPERTIES OF STEEL AND POLYESTER
FIBER
LITERATURE STUDY ON VARIOUS FIBRES
NEED FOR PRESENT STUDY
DEFINATION OF HYBRID FIBER
A composite can be stated as a hybrid when two
and more type of fibers are used in a combined
matrix to produce a composite that will reflect the
benefits of each of the individuals fibers used This
will finally provide synergetic response to the
whole structure. Such composite of concrete is
termed as hybrid fiber reinforced concrete (HFC).
EFFECTS OF HYBRID
FIBER
IN
CONCRETE
• Fibers
are usually
used in concrete to control cracking
due to plastic shrinkage and to drying shrinkage.
• They also reduce the permeability of concrete and thus
reduce bleeding of water
• Reduce steel reinforcement requirements
• Increase toughness and durability
• Improve freeze thaw resistance
PROPERTIES OF STEEL
Properties
Values
Length (mm)
50
Diameter (mm)
1
Aspect ratio(length/dia)
65
Density (g/cm^3)
7.8
Tensile strength(mpa)
800-900
PROPERTIES OF POLYESTER FIBER
Properties
Values
Fiber
Polyester CT 2424
Cutting length
12mm
Effective Diameter
0.2-0.4mm
Specific gravity
1.34-1.39
Melting point
250-260 C
Elongation
20-60%
Young's modulus
>500Mpa
.
ADVANTAGES OF HYBRID FIBER
REINFORCED CONCRETE
1. Crack Bridging at two stages is carried
out: As two types of fibers are used, one will
treat the initial micro cracks. Further chances of
macro cracks are treated by next type of fibers.
This is not achieved by a single type of fiber.
 2. Two or more types of system: One type
provides strength and stiffness. The other type
will gain flexibility and ductility.
 3. It can use fiber with different durability. The
strength and toughness are increased by using
durable fiber.

LITERATURE SURVEY






Dr. Md. Saiful Islam et al. concluded both the compressive & flexural strength of concrete are
observed to increase with the inclusion of steel fiber. The improvement depends on the fiber
volume fractions and its aspect ratios.
The compressive & flexural strength of concrete enhances up to 1.5% & 2% of steel fiber content
respectively and then decreases with the increase of fiber content. 1.5% & 2% steel fiber content is
found as optimum fiber content for compressive & flexural strength respectively.
After 28 days curing, the increase in compressive strength for SFRC is reported to vary in the
range of 4 to 24% whereas for flexural strength, the corresponding increase varies from 40 to 70 %.
Both compressive and flexural strength values of SFRC increase with the increase in aspect ratio
of fiber. The increase in compressive strength was observed as 6% as aspect ratio changes from 50
to 70. In flexural strength, the corresponding value was reported as 11 %.
The plain concrete beam specimen failed completely at a certain load whereas the beam specimens
with steel fiber showed gradual failure and a clear flexural crack. The flexure crack developed in
SFRC beam specimens were limited to hair cracks only in most of the cases.
The load-deflection characteristics & cracking/failure pattern of the SFRC specimens indicated to
improved ductility over plain concrete. Also inclusion of fibers in concrete are observed to improve
its flexural strength more effectively as compared to compressive strength.
LITERATURE SURVEY









Ch. Hanumantha Rao et al. concluded the use of recycled PET fibres
in concrete as a waste material by assessing their effect in concrete
specimens.
The addition of PET in the ratios of 0.5%, 1%, 1.5%, reduced the
workability of the manufactured concrete.
The significant improvements in strengths were observed with
inclusion of plastic fibers in concrete.
The optimum strength was observed at 0.5% of fiber content for all
type of strengths.
To expand the use of PET fiber, the cost will need to be considered.
At this stage the market price is comparable to that of steel fiber,
when the same volumes are being compared.
In addition, its use as pavement on narrow, winding, and steep roads
can be considered.
The PET fibres incorporation does not significantly change the
magnitude of the mortar compressive strength.
The use of recycled materials added to concrete is a technology that
can constantly be improved, regarding technical and environmental
conditions.
In this research it has been proposed the use of PET bottles to obtain
reinforcing fibers to increase the ductility of concrete.
MIX DESIGN


Mix Design calculation for M40 Grade :
Initial Parameters :

1)Cement : OPC 53

2) Concrete Grade : M 40

3) Specific Gravity of Cement : 3.12

4) Fine Aggregate : Sand – Zone II

5) Specific Gravity Of Fine Aggregate : 2.65

6) Coarse Aggregate : 20mm : 10mm

7) Specific Gravity Of coarse Aggregate : 2.85

8) Design Mix Target Slump : 90 – 100mm

1]Target Mean Strength :

F‟ck = Fck + 1.65 x S = 40 + 1.65 x 5 = 48.25 N/mm2

Where,

Fck’ = target average compressive strength at 28 days

Fck = characteristic compressive strength at 28 days , and

S= Standard Deviation
MIX DESIGN

2]Determination of W/C Ratio :

As per IS 456 :2000 max w/c for moderate exposure is 0.45

But from practical experience w/c ratio is 0.4 but 0.38 is adopted w/c = 0.4

W/c ratio varies from 0.3 to 0.4 using graph , max w/c = 0.5 .

For Moderate Exposure w/c = 0.38.

Selection of water Content :

SR. No Size of Aggregate (mm)

1
10
208

2
20
186

3
40
165
Maximum Water content (L)
MIX DESIGN





3] Determination of water Content :
Maximum Water Content for 20 mm Coarse aggregate = 186 liters
So , Water content = 186+6 % = 197.16 Kg.
3% increase for every additional slump of 25 mm.
The admixture that we have used is a water reducer Admixture ; and
it decreases the water content by 18 % .

So , the new water content is 197.16 - 18% of 197.16 = 161.67 liters

4]Calculation of Cement content :

W/C = 0.38

The water Content = 161.67 liters

Cementitious Content = 161.67/ 0.38 = 425.48 kg/m^3
MIX DESIGN
5]Calculation of Volume and Coarse aggregate
and fine aggregate

W/ C= 0.38
 It is less than 0.5-0.38 = 0.12
 Coarse aggregate is increased at the rate of 0.01
for every decrease in w/c rate of 0.05
 For Zone II - W/C = 0.5
 Coarse Aggregate = 20 mm
 Volume of Coarse Aggregate = 0.62
 So for W/C ratio =0.38
 Volume of Coarse aggregate = 0.62+0.02 = 0.64
 Volume of Fine aggregate = 1 - 0.64 = 0.36

MIX DESIGN

6]Design Mix Calculation

(I). Volume of Concrete = 1 m^3

(II). Volume of Cement = Mass of Cement / Specific Gravity * 1000
= 425.48 / 3.12 * 1000







= 0.14 m^3
(iii). Volume of water = Mass of water / Specific Gravity of water * 1000
= 161.67 / 1 * 1000
= 0.161 m^3
(iv). Volume of entrapped air = 0.02m^3
(v). Volume of all Aggregate ( fine + Coarse ) = Volume of concrete (Volume of
cement + volume of water + volume of
entrapped air )
=1-

(0.14+0.161+0.02)

=0.679
MIX DESIGN

(vi). Mass of coarse aggregate= Volume of all aggregate *volume of coarse aggregate*
specific gravity of coarse aggregate *1000

=0.679*0.64*2.85*1000

=1238.49 kg

(vii).Mass of fine aggregate =Volume of all aggregate* volume of fine aggregate*
specific gravity of fine aggregate*1000

=0.679*0.36*2.65*1000

=647.76 kg

Mix Proportion:

Cement=425.48kg/m^3

Coarse Aggregate= 1238.49 kg/m^3

Fine Aggregate= 647.76 kg/m^3

Water= 161.67 liters/m^3

W/C ratio= 0.38

volume of admixture=0.7*425.48=298 ml

Cement: Fine Aggregate: Coarse aggregate :Water

1
:1.52
: 2.91
:0.38
RESULTS
COMPRESSION TEST RESULTS
SF
0
0
0.5
0.5
1
1
1.5
1.5
2
2
0.5
0.5
1
1
1.5
1.5
2
2
0.5
0.5
1
1
1.5
1.5
2
2
0.5
0.5
1
1
1.5
1.5
2
2
PF
0
0
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
1
1
1
1
1
1
1
1
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
2
2
2
2
2
2
2
2
LOAD(KN)
720
1116
734.4
1120
748.68
1124
812
1140
800
1137.5
798
1135.5
795
1136.86
790
1134
792
1133
794
1121
794
1124
795
1126
782
1128
785
1129
788
1121
778
1124
780
1129
STRENGTH(N/MM^2)
32
49.6
32.64
49.78
33.29
49.95
36.08
50.67
35.85
50.55
35.46
50.46
35.33
50.44
35.11
50.4
35.2
50.35
35.28
49.82
35.28
49.95
35.33
50.44
34.75
50.13
34.88
50.18
35.02
49.82
34.57
49.95
34.67
50.17
SPLIT TENSILE TEST RESULTS
SF
0
0
0.5
0.5
1
1
1.5
1.5
2
2
0.5
0.5
1
1
1.5
1.5
2
2
0.5
0.5
1
1
1.5
1.5
2
2
0.5
0.5
1
1
1.5
1.5
2
2
PF
0
0
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
1
1
1
1
1
1
1
1
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
2
2
2
2
2
2
2
2
LOAD(KN)
89.86
128.82
95.83
146.42
94.88
152.38
98.03
154.56
92.69
140.13
91.75
142.02
89.86
145.16
85.46
150.50
88.29
131.65
82.32
137.93
82.95
153.64
91.74
146.73
83.26
135.73
85.46
141.07
87.66
142.33
90.80
153.64
91.43
153.33
STRENGTH(N/MM^2)
2.86
4.10
3.05
4.66
3.02
4.85
3.12
4.92
2.95
4.46
2.92
4.52
2.86
4.62
2.72
4.79
2.81
4.19
2.62
4.39
2.64
4.89
2.92
4.67
2.65
4.32
2.72
4.49
2.79
4.53
2.89
4.89
2.91
4.88
FLEXURAL TEST RESULTS
SF
0
0
0.5
0.5
1
1
1.5
1.5
2
2
0.5
0.5
1
1
1.5
1.5
2
2
0.5
0.5
1
1
1.5
1.5
2
2
0.5
0.5
1
1
1.5
1.5
2
2
PF
0
0
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
1
1
1
1
1
1
1
1
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
2
2
2
2
2
2
2
2
LOAD(KN)
14.17
23.96
14.85
25.54
13.78
26.21
14.63
26.16
16.43
28.01
16.09
27.68
15.81
27.11
15.52
27.06
14.96
26.66
13.61
26.1
13.78
26.33
13.73
26.1
14.85
26.55
15.3
27.34
15.53
27.62
13.61
27.34
14.28
27.56
STRENGTH(N/MM^2)
2.52
4.26
2.64
4.54
2.45
4.66
2.6
4.65
2.92
4.98
2.86
4.92
2.81
4.82
2.76
4.81
2.66
4.74
2.42
4.64
2.45
4.68
2.44
4.61
2.64
4.72
2.72
4.82
2.76
4.91
2.42
4.86
2.54
4.9
COMPRESSION TEST
7 DAYS
COMPRESSION TEST
28 DAYS
SPLIT TENSILE TEST
7 DAYS
SPLIT TENSILE TEST
28 DAYS
FLEXURAL RESULTS
7 DAYS
FLEXURAL RESULTS 28 DAYS
CONCLUSION
COMPRESSIVE STRENGTH :
The test was conducted as per IS 516-1959 codal provision. For
cube compression tests on concrete, cube of size 150 mm was
employed. All the cubes were tested in saturated condition after
wiping out the surface moisture from the specimen. The tests
were carried out at a uniform stress after the specimen has been
centered in the testing machine. For all mixes compressive
strengths were determined at 7 days and 28days. The results of
compressive strength were presented in Table . The cubes were
tested using Compression Testing Machine (CTM) of capacity
2000Kn. The maximum compressive strength is observed at 1.5%
steel fiber and 0.5% polyester fiber in M40.
SPLIT TENSILE STRENGTH :
The test was conducted as per IS: 5816-1999 codal
provisions. For split tensile strength, the cylinder
of 100mm diameter and 200mm height were used.
In replacement of Steel fiber and polyester fiber,
the splitting tensile strength of steel fiber and
polyester fiber concrete showed to be higher than
that of the conventional concrete. The maximum
split tensile strength was obtained at 1.5% steel
fiber and 0.5% polyester fiber
FLEXURAL STRENGTH :
The test was conducted as per IS: 516-1959 codal
provisions. Flexure strength was measured by
loading 150mm x150 mm x 700 mm concrete beams
with a span at least three times the depth. Flexural
strength of steel fiber and polyester fiber concrete
seemed to be increased at 2% steel fiber and 0.5%
polyester fiber.
FUTURE SCOPE
As we concluded that maximum strength of
compression was achieved in 1.5% SF and 0.5%
PF so these ratios can be used in concrete
 Moreover as we include Steel Fiber, the amount
of reinforcement needed will be decreased by our
results , study and the practical experience.
 Also when we include Polyester Fiber the
compressive strength has also increased.
 By the use of these fibers in combine the split
tensile as well as flexural strength is also
increased when compared with normal concrete.
