mechanical properties of hybrid fiber reinforced blended concrete

1. EXPERIMENTAL STUDY ON MECHANICAL
PROPERTIES OF HYBRID FIBER REINFORCED
BLENDED CONCRETE

2. CONTENTS
• ABSTRACT
• INTRODUCTION
• LITERATURE REVIEW
• EXPERIMENTAL PROGRAMME
• RESULTS AND DISCUSSION
• CONCLUSION
• SCOPE OF WORK
• REFERENCES

3. ABSTRACT
• Plain concrete exhibits a low strength characteristics and weak resistance to the crack development. Internal micro-
cracks are present in concrete even before loading due to shrinkage or other causes of volume change.
• In order to increase the strength parameters of concrete a wide range of replacements and addition of different fibers
in concrete are increased, by these combinations of different fibers and admixtures to the concrete may have
sustainable development in strength characteristics.
• My project is divided into 3 phases, in the first phase the OPC is partially replaced with Metakaolin of 5%, 10%,
15% and 20% and Dolomite of 5%, 10%, 15% and 20% (mineral admixtures) and optimum value is to be
determined by studying the hardened properties of concrete.
• In the second phase with the addition of hybrid fibers 0.5%, 1.0%, 1.5% and 2% to the concrete and optimum value
is to be determined by studying the hardened properties of concrete.
• In the third phase, the optimum values of both mineral admixtures and hybrid fibers combination are used to study
the mechanical properties of hybrid fiber reinforced blended concrete.

4. INTRODUCTION
Hybrid fiber reinforced concrete
• A composite is a hybrid of two or more kinds of fibers bonded in a common matrix to form a composite
material that benefits from each of the constituent fibers and has a synergetic value. The introduction of
short discontinuous fibers considerably enhances the mechanical qualities of concrete. It boosts elastic
modulus, decreases brittleness in concrete, and controls fracture formation, growth and propagation.
• The necessity of hybrid fiber reinforced concrete in different construction sector has been improved. Hence
the research expels the practicality of hybrid fiber reinforcement with a sufficient grade of concrete.
• Fibers can be in form of Metallic fibers, Mineral fibers, Synthetic fibers and Natural fibers.

5. Types of Fibers
1. Metallic fibers (stainless steel, aluminium and copper)
2. Mineral fibers(Asbestos, graphite and glass)
3. Synthetic fibers (Nylon, Carbon and polypropylene)
4. Natural fibers (Sugarcane bagasse, bamboo, jute and Wood)

6. Types of fiber reinforced concrete
1. Steel Fiber Reinforced Concrete
2. Polypropylene Fiber Reinforced Concrete
3. Glass Fiber Reinforced Concrete
4. Carbon Fiber Reinforced Concrete
5. Nylon Fiber Reinforced Concrete

7. Advantages of Hybrid fibers
• 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.
• One type provides strength and stiffness, the other type will gain flexibility and ductility.
• It can use fiber with different durability, the strength and toughness are increased by using durable fiber.

8. Hook end Steel Fibers
Steel fiber (SF) is the most often utilized form of fiber for
concrete reinforcement. These are made up of short
discrete fibers that are scattered evenly and randomly in
concrete. Fibers are utilised in concrete to prevent and
regulate plastic and drying shrinkage. The addition of
Steel fibers to concrete boosts its flexural and toughness
substantially.

9. Carbon fibers
Carbon fiber is a synthetic material that obtains great
strength, stiffness, and lightweight in a single package.
Carbon fiber composites are stronger which is 10 times
stronger and 5 times lighter than steel, and 1.5 times
lighter than aluminium. Carbon fiber composites are also
noted for being exceptionally corrosion resistant and
able to tolerate heavy loads.

10. BLENDED CONCRETE
Blended concrete is defined as combination of two or more mineral admixtures. It is a mixture of two different
properties of materials are combined to enhance the properties of concrete and enhances strength to concrete
when compared with normal concrete.
Significance
• It is a partial replacement to the cement
• It reduces the bleeding in concrete
• It enhances strength parameter
• Low-cost material (mineral admixtures) can be used and abundant availability

11. Metakaolin
Ordinary clay and kaolin clay that has been thermally
treated are formed as metakaolin, and the particle size
of the material in its non-purest form is smaller than
cement particles. It is not a byproduct of industry like
the other admixtures.

12. Dolomite
It is also known as "dolostone" and "dolomite rock,"
and is a sedimentary rock that is mostly formed of the
mineral dolomite, CaMg(CO3)2.It is formed as a result
of magnesium-rich groundwater altering of lime mud
and limestone after deposition

13. Literature Review
• Hamdy K. Shehab El-Din. (2017). In this study, they have investigated that the optimum percentage of
metakaolin at 15 per cent and fibers ratio of 0.25% and 0.5% (steel and polypropylene) are included and
concrete grade of 60 MPa and evaluated characteristics of compressive, split tensile and bond strength. The
correlation has taken in between them and strength has been developed.
• Adanagouda. (2021).In this study, they have investigated that the optimum percentage of metakaolin at 5 per
cent and fibers varying proportion of 0, 0.5, 0.75 and 1.0% for polypropylene and for steel fibers 0, 0.75, 1.0
and 1.25% and Metakaolin replacement percentages are 0 10 20 and 30% and three different ratios 0.275
0.325 and 0.375 and aggregate binder ratio 1.75 are constant.
• Dejia Liu.(2018). Examines the study on carbon fibers when addition to concrete to get the high-quality
concrete and sand ratio of 31% with percentage range of 0.2 to 1% of CFs and peak value registered at 0.8%.
Mixing of CFs had great influence on early age compressive strength. At 28 days the strength is 35.39 N/mm²
and early strength is observed at 3 and 7days with increase strength 26.36 and 27.95N/mm² .

14. • V.Sivakumar.(2020). In this study, they have investigated that steel fiber and polypropylene crossover strands
mixes as extend of 80-20% 70-30% and 60-40% and grade of concrete is M60 grade and volume proportion of
1.5% of hybrid fiber. The final conclusion is that the quality test outcomes is 80 per cent steel filaments and
20% polypropylene for blend 1 is achieved for compressive quality and flexural test quality is 16%.
• Alisa Machner. (2017). Examines the study on dolomite and metakaolin and peak value registered at 10% of
cement replacement. The Portland metakaolin cement up to 20% wt with dolomite or limestone, the test was
conducted in different temperatures like 5, 20, and 38 ᵒC and strength developed at 90days.

15. EXPERIMENTAL PROGRAMME
Materials used
• Cement
• Fine aggregate
• Coarse aggregate
• Mineral admixtures
• Hybrid fibers

16. Cement
• Ordinary Portland cement (OPC 53 grade) was used through out the experimental work.
Physical properties of cement
S.No Property Result
1 Normal consistency 30 %
2 Initial and final setting
time
35 and 480 min
3 Specific gravity 3.12
4 Fineness of cement 95 %

17. Fine aggregate
Physical properties of fine aggregate
S.No Property Result
1 Specific gravity 2.64
2 Zone II
3 Fineness modulus 2.55

18. Coarse aggregate
Physical properties of Coarse aggregate
S.No Property Result
1 Specific gravity 2.72
2 Fineness modulus 6.79

19. Mineral admixtures
Physical properties of dolomite
1. Chemical composition CaMg(CO3)2
2 Colour White
3 Specific gravity 2.9
4 Fineness 93%
5 Crystal system Hexagonal

20. Physical properties of Metakaolin
1. Chemical composition SiO2 & Al2O3
2. Colour Off-white
3. Specific gravity 2.5
4. Fineness 95%
5. Physical form Powder

21. Chemical composition percentage of OPC, metakaolin and
dolomite
S. No Major Components Cement Dolomite Metakaolin
01 CaO 65.0% 54% 12%
02 SiO2 20.0% 2% 52%
03 Al2O3 4.90% 2% 26%
04 MgO 3.10% 36% 4%
05 Loss of Ignition 2.40% - -
06 Fe2O3 2.30% - 6%
07 SO3 2.30% - -
08 K2O 0.40% - -
09 Na2O3 0.20% - -

22. Steel fibers
Physical properties
S.No Properties Steel fiber
1 Length of fiber, mm 25
2 Diameter, mm 0.5
3 Aspect ratio 50
4 Tensile strength, MPa 210
5 Elastic modulus, GPa 160

23. Carbon Fibers
Physical properties
S.No Properties Carbon fiber
1 Length (mm) 6-10
2 Diameter (micron) 12
3 Tensile strength (MPa) 1200-4500
4 Elastic modulus (GPa) 200-650

24. Types of fibers
Types Tensile strength
(Mpa)
Elastic modulus
(10³ Mpa)
Ultimate
elongation
(%)
Specific Gravity
Steel 210-2750 160 0.5-3.5 2.50
glass 1034-3792 69 1.5-3.5 3.20
Asbestos 551-965 89-138 0.60 1.50
carbon 1200-4500 200-650 15 1.80
cotton 413-689 4.82 3-10 1.10
Nylon 858-827 4.13 16-20 0.50
Polypropylene 551-758 3.45 24 1.10

25. Casting of specimens
• Mixing process is done with concrete mixer
• After the completion of mixing the test on fresh properties of concrete i.e.., slump cone test
• The moulds are arranged in a flat surface and well mixed concrete is placed and compacted

26. Demoulding of specimens
• After 24 hours of casting the test specimens are demoulded carefully and should be shifted to
curing tank

27. Curing of specimens
• The specimens are transferred to curing tank after demoulding and should be placed until the
required time period for testing.

28. Tests on concrete
• To evaluate the mechanical properties of concrete the following tests are to be conducted and results are
tabulated
• The listed below tests are conducted over for the conventional concrete (i.e., for M30 grade) and relatively
compared over for the replaced specimens with hybrid fiber reinforced blended concrete
• Compression test
• Split tensile test
• Flexural test

29. Compressive strength test
 The compressive strength is measured using cube specimens. The
dimension of the cube specimen is 150 x150 x 150 mm. The compressive
strength of three cubes is measured after 7, 14, and 28 days.
 The compressive strength f Ꞌ
c =
𝑷
𝑨
 The capacity of the testing machine is 2000 KN.
 The load is applied gradually for specimen.
 The compressive strength of concrete is determined by breaking cube
specimen in a compression testing machine.

30. Split tensile test
 The split tensile strength is measured by using cylinder specimens. The size
of the cylinder specimen diameter of 150 mm and height 300 mm. The split
tensile strength for cylinder is measured after 7, 14, and 28 days interval.
 The split tensile strength f ct =
𝟐𝑷
𝝅𝒅𝒍
 The capacity of the testing machine is 2000 KN.
 The load is applied gradually for specimen.

31. Flexural strength test
• The flexural strength is measured by using prism specimens.
The size of the prism specimen is 100 X 100 X 500 mm. the
flexural strength of prism is measured after 7, 14, and 28 days.
• The flexural strength f b =
𝟑𝒑𝒂
𝒃𝒅𝟐 For a > 110 mm & a < 133 mm
f b =
𝑷𝑳
𝒃𝒅𝟐 For a > 133 mm
• The specimen is tested under universal testing machine
• At peak load the specimen gets cracked and ultimate load is
recorded.

32. Compressive strength for different metakaolin percentages
Metakaolin (%)
Compressive strength (MPa)
7 days 28 days
0 26.54 40.25
5 35.96 45.65
10 30.51 43.15
15 29.65 42.45
20 27.70 39.65
26.54
35.96
30.51 29.65
27.7
40.25
45.65
43.15 42.45
39.65
0
5
10
15
20
25
30
35
40
45
50
0 5% 10% 15% 20%
Compressive
strength
(Mpa)
Metakaolin
7 days 28 days

33. Compressive strength for different dolomite percentages
Dolomite (%)
Compressive strength (MPa)
7 days 28 days
0 26.54 40.25
5 28.95 41.25
10 34.35 44.85
15 31.75 43.95
20 30.05 39.65
26.54
28.95
34.35
31.75
30.05
40.25 41.25
44.85 43.95
39.65
0
5
10
15
20
25
30
35
40
45
50
0 5% 10% 15% 20%
Compressive
strength
(Mpa)
Dolomite
7 days 28 days

34. Compressive strength for different Hybrid fibers percentages
Hybrid fibers
(%)
Compressive strength (MPa)
7 days 28 days
0 26.54 40.25
0.5 27.24 41.21
1.0 30.04 41.62
1.5 33.25 43.15
2.0 30.50 42.71
26.54 27.24
30.04
33.25
30.5
40.25 41.21 41.62
43.15
42.71
0
5
10
15
20
25
30
35
40
45
50
0 0.5% 1.0% 1.5% 2.0%
Compressive
strength
(Mpa)
Hybrid fibers
7 days 28 days

35. Compressive strength for different types of concrete
Type Compressive strength (MPa)
7 days 14 days 28 days
Conventional 26.54 31.65 40.25
Blended
concrete
33.85 38.92 41.46
Hybrid fiber
reinforced
blended
concrete
39.14 42.48 46.32
26.54
33.85
39.14
31.65
38.92
42.48
40.25
41.46
46.32
0
5
10
15
20
25
30
35
40
45
50
Conventional concrete Blended concrete hybrid fiber reinforced blended
concrete
Compressive
strength
(N/mm
2
)
7 days 14 days 28 days

36. Split tensile strength for different types of concrete
Type
Split tensile strength (MPa)
7 days 14 days 28 days
Conventional 2.60 2.75 3.26
blended
concrete
2.70 2.90 3.60
Hybrid fiber
reinforced
blended
concrete
3.56 3.65 4.17
2.6
2.7
3.56
2.75
2.9
3.65
3.26
3.6
4.17
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
Conventional concrete blended concrete Hybrid fiber reinforced
blended concrete
Split
tensile
strength
(N/mm
2
)
7 days 14 days 28 days

37. Flexural strength for different types of concrete
Type Flexural strength (MPa)
7 days 14 days 28 days
Conventional 4.50 5.40 6.80
Blended
concrete
8.08 9.49 11.60
Hybrid fiber
reinforced
blended
concrete
8.45 10.83 14.60
4.5
8.08
8.45
5.4
9.49
10.83
6.8
11.6
14.6
0
2
4
6
8
10
12
14
16
Conventional concrete blended concrete Hybrid fiber reinforced blended
concrete
Flexural
strength
(N/mm
2
)
7 days 14 days 28 days

38. CONCLUSIONS
1. The compressive strength to a conventional concrete and HFRBC varying a percentage of 47%, 34% and
28% at interval of 7, 14 and 28days.The observation in the compressive strength have higher percentage
variation at 7days.
2. The split tensile strength to a conventional concrete and HFRBC varying a percentage of 37%, 33% and
28% at interval of 7, 14 and 28days.The observation for split tensile strength have higher percentage
variation at 7 days when compared to remaining interval.
3. The flexural strength to a conventional concrete and HFRBC varying a percentage of 88%, 101% and 115%
at interval of 7, 14 and 28days.The observation for flexural strength have higher percentage variation at
28days when compared to remaining interval. The flexural strength which is observed that higher variation
among three strength parameters mainly this due to the hybrid fibers (carbon and steel) which is capable to
resist higher loads and minimise the crack formation.
4. The final conclusion for the study on mechanical properties of hybrid fiber reinforced blended concrete
exhibits good mechanical properties when it is compared with conventional concrete and blended concrete.

39. SCOPE OF WORK
• To study the strength of concrete with different fibers combination and mineral admixtures.
• To study the optimum values of different percentages with metakaolin, dolomite and hybrid fibers
( Hook end steel fibers and carbon fibers)
• To study the mechanical properties of Hybrid fiber reinforced blended concrete.

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43. Thank you..