Hybrid concrete using polypropylene and steel

1. STUDY ON MECHANICAL PROPERTIES OF
CROSS FIBRE REINFORCED CONCRETE USING
TERMOPLASTIC AND STEEL FIBRE
SANJEEVKUMAR .S (7101121413015)
.
Submitted by,

2. ABSTRACT
 The use of two or more types of fibres in a suitable combination may potentially improve the overall properties of
concrete and also result in performance concrete. The combining of fibres, often called hybrid fibre, is investigated
in this project for a M30 grade concrete.
 This project focuses on the experimental investigation carried out on hybrid fibre reinforced concrete up to a total
fibre volume fraction of 0.25%, 0.5%, 0.75% and 1% which was prepared using normal mixing, compaction and
curing conditions.
 At this volume fraction, flexural toughness and ductility of hybrid fibre concretes comparable to steel fibre
concretes Increased fibre availability in the hybrid fibre systems, in addition to the ability of non-metallic fibres of
bridging smaller micro cracks, are suggested as the reasons for the enhancement in flexural properties.

3. SUMMARY OF LITERATURE REVIEW
Hybrid fibre reinforced concretes significantly improve the ductility
performance of reinforced concrete specimens.
Hybrid fibre reinforced concretes significantly enhance flexural strength.
Modulus of rupture of hybrid fibre reinforced concretes increases
significantly.
Hybrid fibre reinforced concrete specimens increases the deflection
compared to plain concrete.
Hybrid fibre reinforced concrete reduces crack widths.

4. OBJECTIVES OF THE PROJECT
 To explain the use of polypropylene –steel fibres to improve the performance of
the reinforced concrete beams.
 To increase the ultimate strength of the reinforced concrete beams
 To study the mechanical properties of polypropylene-steel fibre concrete
 To investigate the suitability of hybrid fibre reinforced concretes

5. SCOPE
 To study the ultimate load carrying capacity of reinforced concrete beams using
polypropylene and steel fibres percentages varying from 0%,0.25%,0.5%and 1%, as
Hybrid.
 To study experimentally the flexural behaviour of reinforced concrete beams using steel
and polypropylene fibres.
 To understand the failure mechanisms of the flexural member.

6. METHODOLOGY
This project is carried out as per the following method.
 The properties of steel and polypropylene fibre are to be studied by carrying out
ductility and flexural strength test. Then the steel and polypropylene fibres are added in
concrete beams with various proportions as 0.25%, 0.5%, 0.75% and 1% by volume
fraction to form hybrid concrete and the specimens are to be subjected to loading
separately up to the failure. The load carrying capacity, deflection and crack pattern of
the concrete beams are to be studied.

7. STEEL FIBRES AND POLYPROPYLENE FIBERS

8. EXPERIMENTAL INVESTIGATION
 The specific gravity of the cement tested is 3.10
 The initial and final setting time of the cement is 55 minutes and 720 minutes respectively.
 The specific gravity of the fine aggregate tested is 2.64.
 The fineness modulus of the aggregate tested is 2.85%
 The specific gravity of the coarse aggregate tested is 2.86.
 The fineness modulus of coarse aggregate tested is 7.27.
 The mix design for M30 concrete is arrived as 1: 1.64: 2.66

9. COMPRESSIVE STRENGTH RESULTS FOR CUBER
 Compression test on concrete cubes has been carried out conforming to IS 516-1999. All the
concrete cube specimens were tested in a 2000 kN capacity compression testing machine. The
crushing strength of concrete cube is determined by applying compressive load at the rate of
140 kgf/cm2/min or 140 kN/min till the specimen fail. After 28 days of curing, the cubes were
then allowed to become dry for few hours before testing. Plane surfaces of the specimen were
between the platens of compression testing machine and subjective to loading. The
compressive strength of controlled concrete and other composite specimen are given Table 5.10

10. DETAILS OF M30 GRADE PROPORTIONS
No. of Specimen Description
of specimen
Fibre Volume
Fraction (Vf) in %
Poly Propylene
fibre in %
Steel Fibre in % No of Cubes
1 control NC 0 0 7th day 28th day
2 C1
0.25
100 0 3 3
3 C2 70 30 3 3
4 C3 30 70 3 3
5 C4 0 100 3 3
6 C5
0.5
100 0 3 3
7 C6 70 30 3 3
8 C7 30 70 3 3
9 C8 0 100 3 3
10 C9
0.75
100 0 3 3
11 C10 70 30 3 3
12 C11 30 70 3 3
13 C12 0 100 3 3
14 C13
1
100 0 3 3
15 C14 70 30 3 3
16 C15 30 70 3 3
17 C16 0 100 3 3

11. COMPRESSIVE STRENGTH OF THE CUBE AT 7 DAYS & 28 DAYS
No. of
Specimen
Description of
Specimen
No. of
Specimen
Poly
Propylene
fibre in %
Steel Fibre in %
Compressive
strength 7 days
N/mm2
Compressive
strength 28 days
N/mm2
1 CONTROL NC -- -- 25.35 36.22
2 C1
0.25
100 0 27.66 39.51
3 C2 70 30 25.58 36.54
4 C3 30 70 31.98 45.68
5 C4 0 100 29.39 41.98
6 C5
0.5
100 0 27.66 39.51
7 C6 70 30 23.16 33.09
8 C7 30 70 31.28 44.69
9 C8 0 100 30.25 43.21
10 C9
0.75
100 0 27.14 38.77
11 C10 70 30 32.49 46.42
12 C11 30 70 31.28 44.69
13 C12 0 100 28.18 40.25
14 C13
1
100 0 32.67 46.67
15 C14 70 30 33.53 47.90
16 C15 30 70 36.47 52.10
17 C16 0 100 32.84 46.91

12. DISCUSSION ON COMPRESSIVE STRENGTH
 The compressive strength of Hybrid concrete specimens were found to be more than that of control
specimen indicating that the addition of steel-polypropylene fibres are contributing to the strength
 The compressive strength of 0.25% Hybrid concrete specimens, it was found that of all specimens was
more than that of control specimen indicating that the addition of 30-70 (Polypropylene-Steel) is
contributing to the maximum compressive strength.
 The compressive strength of 0.5% Hybrid concrete specimens, it was found that of all specimens was
more than that of control specimen except C6 indicating that the addition of 30-70 (Polypropylene-
Steel) is contributing to the maximum compressive strength

13. DISCUSSION ON COMPRESSIVE STRENGTH
 The compressive strength of 0.75% Hybrid concrete specimens, it was found that of all specimens were
more than that of control specimen indicating that the addition of 70-30 (Polypropylene-Steel) is
contributing to the maximum compressive strength.
 The compressive strength of 1% Hybrid concrete specimens, it was found that of all specimens was
more than that of control specimen indicating that the addition of 30-70 (Polypropylene-Steel) is
contributing to the maximum compressive strength. It was concluded that increase in compressive
strength has been observed in all cases except C6. 30-70 (Polypropylene-Steel) contributes maximum
compressive strength.

14. SPLIT TENSILE STRENGTH RESULTS FOR CYLINDERS
S.NO Reference code Volume fraction in %
Hybrid fibre volume fraction
(PP-Steel) %
Split Tensile strength in
Mpa
1. S1 (Control) 0 0-0 1.9
2. S2 1% 100-0 2.2
3. S3 1% 80-20 2.8
4. S4 1% 60-40 3.9
5. S5 1% 40-60 3.3
6. S6 1% 20-80 3.7
7. S7 1% 0-100 3.2

15. DISCUSSION ON SPLIT TENSILES STRENGTH
 The The result of tensile strength shows that the strength of hybrid fiber concrete of 1%
volume fraction with 60-40 (Polypropylene-Steel) is 105.26% higher than ordinary
control specimen. The increase in split tensile strength varies from 15.79% to 105.26%.
In all cases, increase in split tensile strength over control concrete has been observed.

16. TEST SPECIMEN SETUP
 The specimens are beams of size 1700mm x 150mm x 100mm, reinforced with 3
Numbers of 8mm diameter HYSD bars in tension and 2 Numbers of 8mm diameter
HYSD bars in compression zone as hanger rods. The specimen is also provided with
shear reinforcements in the form of 6mm diameter mild steel bar two legged stirrups at
100 mm centre.

17. EXPERIMENTAL SETUP

18. LOAD DEFLECTION BEHAVIOUR
 Load vs deflection plot has been drawn for all test specimens from the experimental
data. The behaviour of test specimens is compared the plots. The first crack and
failure load were recorded along with the corresponding displacements and strains.

19. RESULTS AND DISCUSSION
Specimen
Ultimate Failure(Pu)
Load (kN)
Ultimate Failure
Moment (kNm)
Ultimate Deflection (mm) First Crack
Load (kN)
Mode of Failure
L/2 L/3 L/4
S1 (control) 33.9625 8.49 10.172 7.060 8.616 10 Under reinforced
S2 36.76 9.19 26.680 23.42 20.15 10 Under reinforced
S3 34.67 8.66 31.567 25.08 19.00 10 Under reinforced
S4 42.80 10.70 15.300 13.641 11.982 10 Under reinforced
S5 39.75 9.93 34.96 30.05 25.13 8 Under reinforced
S6 39.01 9.75 29.789 25.345 21.783 8 Under reinforced
S7 40.04 10.01 21.061 14.952 12.952 8 Under reinforced

20. CONTROL CONCRETE
0
5
10
15
20
25
30
35
40
0 5 10 15 20
Load
in
kN
Deflection in mm
L/2
L/3
L/4

21. DISCUSSION
 Reinforced beam failed in bending zone. After the first crack load of 10kN, the
reinforcement started yielding and more number of cracks has formed in the bending
zone extended towards the point loads with increment in loads. At ultimate load
failure of beam occurred. Large numbers of wide cracks were observed during failure.
The beam takes ultimate load of 33kN.

22. HYBRID FIBRES REINFORCED BEAM (S-2)
0
5
10
15
20
25
30
35
40
0 5 10 15 20 25 30
load
in
KN
Deflection in mm
L/2
L/3
L/4

23. DISCUSSION
 Reinforced beam failed in bending zone. After the first crack load of 10kN, the
reinforcement started yielding and more number of cracks has formed in the bending
zone extended towards the point loads with increment in loads. At ultimate load
failure of beam occurred. Large numbers of wide cracks were observed during failure.
The beam takes ultimate load of 36kN.

24. STIFFNESS
Beams First Crack load (kN)
Mid span deflection at
first crack load (mm)
Stiffness
(kN/mm)
S1(control specimen) 10 1.721 5.81
S2 10 3.844 2.60
S3 8 2.401 3.33
S4 10 0.899 11.12
S5 8 1.617 4.94
S6 8 2.461 3.25
S7 8 1.864 4.29

25. CRACKING BEHAVIOUR
Behaviour of Flexural Failure of Beams
 In the under reinforced section of beam, the member approaches failure due to gradual
reduction of compression zone, exhibiting deflections and cracks, which develop at the soffit
and progress towards the compression face.
 When the area of concrete in compression zone is insufficient to resist the resultant
compressive force, the ultimate flexural failure of the member takes place through the
crushing of concrete. Large deflection and wide cracks are the characteristic futures of the
under reinforced section at failure.

26. CONCLUSION
 The following are the conclusions obtained based on the limited experimental work carried out.
 The physical and mechanical properties of fly ash, metakaolin, and lime sludge and rice husk
ash have been found to be favourable for use in cement concrete as indicates by the
compressive strength of concrete specimens tested.
 The compressive strength of Hybrid concrete specimens were found to be more than that of
control specimen indicating that the addition of steel-polypropylene fibres are contributing to
the strength.

27. CONCLUSION
 The compressive strength of 0.25% Hybrid concrete specimens, it was found that of all
specimens was more than that of control specimen indicating that the addition of 30-70
(Polypropylene-Steel) is contributing to the maximum compressive strength.
 The compressive strength of 0.5% Hybrid concrete specimens, it was found that of all
specimens was more than that of control specimen except C6 indicating that the addition of 30-
70 (Polypropylene-Steel) is contributing to the maximum compressive strength.

28. CONCLUSION
 The compressive strength of 0.75% Hybrid concrete specimens, it was found that of all
specimens were more than that of control specimen indicating that the addition of 70-30
(Polypropylene-Steel) is contributing to the maximum compressive strength.
 The compressive strength of 1% Hybrid concrete specimens, it was found that of all specimens
was more than that of control specimen indicating that the addition of 30-70 (Polypropylene-
Steel) is contributing to the maximum compressive strength. It was concluded that increase in
compressive strength has been observed in all cases except C6. 30-70 (Polypropylene-Steel)
contributes maximum compressive strength.

29. CONCLUSION
 The stiffness values of S4 specimen have more than the other specimen up to first cracked
loaded. This shows that the addition of 1% (60-40) of polypropylene fibre and steel fibre.
 All beams except control specimen has more or less same stiffness values.
 The energy absorption capacities of S2, S3, S4, S5, S6 and S7 specimens more than the control
specimen. This shows that the S1, S2, S3, S4 and S7 specimens offered more resistance to
applied load to compare than other specimen.
 Finally, it is indicated that the steel and polypropylene fibre is to increase the behavior of
reinforced concrete beam.

30. REFERENCES
 Denvid Lau and Oral Buyukozturk (2009), "Moisture Degradation in Concrete/Epoxy Systems", The 9th
International Symposium on Fiber Reinforced Polymer Reinforcement for Concrete Structures , 13-15 July 2009,
Sydney, Australia
 N. Ganesan, P.V.Indira and Sabeena.M.V, " Effect of Hybrid fibres on the Compressive Constitutive Behaviour of
High Performance Concrete under Cyclic Loading, National Conference on Recent Advances in Civil Engineering
(RACE 2012), Nov 29 ‐Dec 01, 2012, CUSAT, Kochi , pp.322‐327
 Shah, S.P. and S.H. Ahmad, High performance concrete: properties and applications. 1994, New York: McGraw-
Hill. xii, 403.

31. REFERENCES
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75,10.4028/www.scientific.net/MSF.610-613.69,Yuan Hua et al., 2009, Materials Science Forum, 610-613, 69,
January, 2009
 Mahyuddin Ramli N., and Nandakuma,.N., (2003). Crack Growth Resistance of Hybrid Fibre Reinforced Cement
Composites, Cement and Concrete Composites, 25, 3-9.
 V Langlois P. Shah (1987). Strength Evaluation and Failure Mechanisms of Fibre Reinforced Concrete,
Proceedings of the International Symposium on Fibre Reinforced Concrete, India, 1-18.
 Yuan Hua, Jie Li, and Kern Wu, (2002). Mechanical Properties of Hybrid Fibre Reinforced Concrete at Low Fibre
Volume Fraction, Cement and Concrete Research, 33, 27- 30.

32. THANK YOU
Regards,
SANJEEVKUMAR .S (7101121413015)