IRJET - Strengthening of Beam using Engineered Cementitious Composites

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 07 Issue: 04 | Apr 2020 www.irjet.net p-ISSN: 2395-0072
© 2020, IRJET | Impact Factor value: 7.34 | ISO 9001:2008 Certified Journal | Page 387
STRENGTHENING OF BEAM USING ENGINEERED CEMENTITIOUS
COMPOSITES
R.Rajendran1, Aakash.S2, Akash.R3, Antony willson.T4, Kaviyarasan.M5
1Assistant Professor, Department Civil Engineering, K.Ramakrishnan College of Technology, Samayapuram,
Trichy, India.
2,3,4,5Under Graduate Students , Department Civil Engineering, K.Ramakrishnan College of Technology, Sama-
yapuram,Trichy,India.
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Abstract - : In this study, the use of Engineered Cementi-
tious Composites (ECC) for the flexural strengthening of
reinforced concrete beams was observed. ECC was pre-
pared using Recron 3S Polyester fibres and Ground-
granulated blast -furnace slag (GGBS). As in the case of
RC, beams are subjected to uniform and continuous load-
ing which increases with the increase in no. of the storey
and may lead to partially damage or even total failure of
the beam. In order to overcome the total failure of RC
beams a layer of ECC is provided to distribute the cracks
uniformly and make the beam even more ductile. Five
beam specimens of M20 grade concrete of cross sectional
dimensions 150mm X 200mm and length 500mm were
made. One of the five beams was taken as the control
specimen. The other specimens were tested after strength-
ening using ECC. Two specimens were Strengthened by
embedding a layer of ECC as the cover in the tension zone
of the beam, by plastering the tension face of the beam
with ECC with GGBS and other two specimens were
Strengthened by ECC without GGBS. The strength charac-
teristics of the ECC layer for different strengthening
methods were also observed by three point flexural
strength test and the results are compared with that of
control specimen.
Keywords: Recron 3s fiber, GGBS, compressive
strength, flexural strength, Engineered cementitious
composites(ECC).
1. INTRODUCTION
1.1 GENERAL
The strength of any reinforced cement concrete (RCC)
flexural member is dependent on the quality of the ma-
terials used, construction practices and age of the con-
crete. Because of aging the structural beam elements
may become degraded. The degradation can be visible
in the form of cracks and excess deformations. Strength-
ening using any superior material will help to overcome
this degradation. In this study the superior material is
recron 3s fiber and GGBS.
1.1 OBJECTIVE
 To increase the shear strength of Beam
 To increase the flexural strength, compressive
strength of the beam, the recron 3s fibre con-
crete layer reduces the cracks.
 However the basic attributes of RFRC are reduc-
tion in shrinkage cracks and improvement in
elastic properties of concrete.
1.2 METHODOLOGY
 Study of materials
 Collection of material
 Test on materials
 Casting of beam and curing
 Flexural test and compression test
 Report submission
2. MATERIALS
2.1 Recron 3s fiber
Recron 3S is a modified polyester fibre. It is gen-
erally used as secondary reinforcing material in con-
crete and soil to increase their performance. Recron 3s
is a triangular polyester fiber in cross section with cut
length of 6mm & 12mm which is being widely used in
the Indian construction industry market. Use of Recron-
3S as a reinforcing material is to increase the strength in
various applications like cement based precast prod-
ucts, filtration fabrics etc.
Fig. 1. Recron 3s fiber

2.1.1 Role of recron 3s fiber
 Controls cracking.
 Reduces water permeability.
 Reduces rebound in concrete- brings direct sav-
ing and gain.
 Increases flexibility.
 Safe and easy to use.
2.2 Ground granulated blast furnace slag
GGBS (Ground Granulated Blast-furnace Slag) is a ce-
mentitious material whose main use is in concrete and
is a by-product from the blast- furnaces used to make
iron. The iron ore is reduced to iron and the remaining
materials form a slag that floats on top of the iron.
Fig. 2. GGBS
3. PREPARATION OF CONCRETE
Ordinary Portland Cement (OPC) of grade 33 was used
for both concrete and ECC mix. The Manufactured sand
was used as fine aggregate (FA) for concrete and ECC.
The fineness modulus for the fine aggregate was 2.7. A
mixture of locally available 20mm and 10mm (60% and
40% respectively) size crushed granite stones were
used as coarse aggregate (CA). The fineness modulus for
coarse aggregate was 7.91. Normal potable water was
used for hydrating the cementing medium. For the
preparation of ECC, GGBS was used as a supplementary
cementitious material. Polyester fibres named Recron
produced by Reliance Industries Limited were used in
ECC mix. Conplast SP430, which is a sulphonated naph-
thalene based super plasticizer (SP), was used for the
mix. The targeted strength for the concrete was
20N/mm2. The ECC mix for this study was prepared
with reference tothe same.
Fig. 3.ECC mix
3.1 Mix proportion
 Concrete is made in the (1:1.5:3 )ratio of M20
grade
 Recon 3s fiber is used in very small amount in
mix of about 0.2% to 0.4% of cement used.
 Ground granulated blast furnace slag(GGBS) is
added 50% as partial replacement of cement in
ECC mix for beam B3.For beam B2 no GGBS is
added with ECC mix.
 The normal dosage range of conplast sp430 is
from 1.00 to 3.00 litres for 100 kg of cementi-
tious material in mix. For high workability con-
crete the normal dosage range is from 0.70 to
2.00 litres/100 kg of cementitious material.
BEAM B1: A conventional beam made of normal M20
concrete.
BEAM B2: Beam with a layer of ECC without GGBS in
tension zone for 25mm and 30mm as cover is provided.
BEAM B3: Beam with a layer of ECC with GGBS in ten-
sion zone for 25mm and 30mm as cover is provided.
3.2 Moulding
Moulding is the process of shaping the liquid or flexible
raw material using a rigid frame called a mould. The
mould size of Beam is 150mm x 200mm x 500mm is
used for the moulding.
Fig. 4.Moulding of beam.
3.3. Demoulding
Demoulding is the process of removing the
shaped material from the mould. Usually the demould-

ing is done after the initial setting time of the concrete.
The initial setting time of concrete is about 24 hours.
Fig. 5.Demoulding of beam
4.TEST PROCEDURE
4.1. Flexural strength
To find out the flexural strength of the beam(modulus of
rupture) we need to find the load at which the beam
fails i.e. at which load cracks starts to appear in the
beam while testing. Test procedure done in UNIVERSAL
TESTING MACHINE(UTM) .Our beam of size
150mmx200mmx500mm is placed in the UTM machine
for three point flexural test. The beam is placed on two
supporting pins at set distance apart and it is subjected
to a concentrated point load at center of the beam.
Fig. 6. Three point flexural test
The beam is placed as the tension zone of the beam is in
the bottom side and the compression zone of the beam
is in top side. Then the load is applied on the beam
gradually until the crakes appear on the beam and the
maximum load can be allowed by the beam is noted.
This is the failure load of the concrete beam. The test is
conducted for all the five beams and their respective
failure load is noted.
The equation for calculation of flexural strength.
FLEXURAL STRENGTH ( )
where,
P=Maximum load applied on beam in kilo New-
ton(KN).
b=width of beam in mm.
d=depth of beam in mm.
L=supported length in mm.
4.1.1 Test result
Table 4.1.1 : show the flexural strength of beam
SPECIMEN TYPE
FAILURE LOAD
(KN)
FLEXURAL STRENGTH
(N/mm2)
14 DAYS 28 DAYS 14 Days 28 Days
SPECIMEN 1(B1) 54 61 3.86 4.28
SPECIMEN 2(B2)
(with cover 25 mm)
62.1 69 4.4 4.85
SPECIMEN 3(B2)
(with cover 30 mm)
65.7 73 4.6 5.11
SPECIMEN 4(B3)
(with cover 25 mm)
69.3 77 4.9 5.39
SPECIMEN 5(B3)
(with cover 30 mm)
70.2 78 2.77 5.49

B3(30mm)
B3(25mm)
B2(30mm)
B2(25mm)
B1(conventional
beam)
61
54
70.2
69.3
73
65.7
69
62.1
78
77
FAILURE LOAD @ 28 DAYS(KN)
FAILURE LOAD @ 14 days(KN)
B3(30mm)
B3(25mm)
B2(30mm)
B2(25mm)
B1(conventional
beam)
3.86
4.6
4.4
4.28
4.95
4.9
5.11
4.85
5.45
FLEXURAL STRENGTH @ 28 DAYS
5.35
FLEXURAL STRENGTH @ 14 days
Different specimen
Fig 6.Comparison of failure loads of different specimen at 14 and 28 days
Different specimen
Fig 7.Comparison of Flexural strength of different specimen at 14 and 28 days
4.1. COMPRESSIVE STRENGTH TEST
The compression strength of concrete is the ability of the concrete to resist the compression loads which acts upon it. It is
measured by crushing cubical concrete specimens in compression testing machine. The following procedure is used to find
out the compressive strength of the hardened concrete. Calculate the mix proportion of concrete and mix the raw materi-
als as per the mix design.
Apply the oil on the sides of the mould and pour the fresh concrete into the mould. Fill the mould with the concrete in
three layers and compacted. Remove the concrete from the mould after the initial setting time of 24 hours the concrete is
cured.
Place the concrete in the compression testing machine. The load is gradually increased until the specimen fails.
Note down the value of failure load. Repeat the procedure for various proportion of concrete and compare their results
with conventional concrete.
Failure
Load(KN)
Flexural
strength
(N/mm
2
)

Fig 8: compression test machine
4.2.2. TEST RESULTS
Table 4.1.1: show the compressive strength of beam.
Fig.9.comparison of compressive strength at 14 and 28
days
Fig.10.comparison of failure load at 14 and 28 days.
4.3. RESULTS ANDDISCUSSIONS
[1] Three point bending test was conducted after 28 days
of curing for the comparison of flexural capacity of
strengthened specimens (B2 and B3) with that of the con-
trol specimen (B1). The load values were acquired using
an electronic load cell and the mid span deformations
were measured with help of UTM. A graph was plotted to
present the load deformation characteristics of the beam
specimens.
[2] It is clear that all the strengthened beams showed bet-
ter load deformation behavior compared to the conven-
tional beam.
[3] The ultimate load at failure for B1 was 65kN. The load
at failure for B2(25mm), B2(30mm),
B3(25mm)andB3(30mm) were 69kN, 73kN, 77kN and
79KN respectively. From the results it is clear that
B3(30mm) showed the maximum load at failure. The de-
flection at failure was less than that of B1. The superior
results of B3 may be due to the effect of confinement
made by the ECC layer.
5. CONCLUSIONS
[1] Embedding a layer of ECC at the tension zone did not
make any considerable difference in the strength charac-
teristics of beam.
[2] Specimen plastered with ECC on the tension face
showed better strength characteristics compared to the
other specimens. This may be due to the confinement
provided by ECC which will assist the tension face con-
crete to arrest tension cracks as well as the side faces to
arrest shear cracks.
[3] The specimen confined with ECC on tension faces
showed better deformation characteristics. This shows
the betterment in deformability. The energy absorbing
capacity of beams with ECC provided only at the tension
face was slightly more compared to control specimen.
[4] The addition of GGBS in the ECC provides more
strength to the beam and carry little more load than B2
and conventional beam.
REFERENCES
[1] S. Prem Kumar, A. J. Jeyaarthi, “Experimental Investi-
gation of Reinforced Concrete Using Recron 3s”, Interna-
tional Journal of Latest Engineering and Management Re-
search, pp.45-52, 2017.
[2] Korrapati Anil Kumar, Dr. Shaik Yajdani, “Study on
Properties of Concrete using Recron 3s Fibre”, Interna-
tional Journal of Science Technology & Engineering,
pp.54-62, 2017.
SPECIMEN
TYPE
FAILURE
LOAD
(KN)
COMPRESSIVE
STRENGTH
(Mpa)
14
days
28
days
14
days
28
days
Conventional
concrete
392 438 17.4 19.5
ECC 399 445 17.8 19.8
ECC with 50%
GGBS
409 454 18.2 20.2
ECC with 50%
GGBS
ECC
18.2
conventional
concrete
17.8
17.4
19.8
19.5
compressive strength @ 14 days
compressive strength @ 28 days
20.2
ECC with 50%
GGBS
ECC
conventional
concrete
409
399
392
454
445
438
FAILURE LOAD(KN) @ 14 DAYS
FAILURE LOAD @ 28 DAYS

[3] Rakesh Kumar Gupta, Mohd Ziaulhaq, “Study of Prop-
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