EXPERIMENTAL INVESTIGATION ON BEHAVIOUR OF SFRC ON …ishitvtech.in/pdf/sajet-vol-3-no7-7.pdf · Concrete is a structural components exist in buildings . South Asian Journal of Engineering

South Asian Journal of Engineering and Technology Vol.3, No.7 (2017) 53-67

53

ISSN No: 2454-9614

EXPERIMENTAL INVESTIGATION ON BEHAVIOUR OF

SFRC ON R.C.C COLUMNS UNDER AXIAL LOAD K.E.Viswanathan

, S.Dhivya

Civil Engineering Department, EBET

*Corresponding Author: K.E.Viswanathan

E-mail: [email protected])

Received: 05/01/2017, Revised: 18/02/2017 and Accepted: 01/04/2017

Abstract

Though Concrete is a widely accepted building material it is not without any drawbacks. The low tensile strength and

brittle nature of concrete necessitates it to be reinforced with steel rods. Placing the steel reinforcement in the tension zone of

concrete will enhance the tensile strength of concrete. The addition of fibers to concrete delays the failure mechanism and

induces ductility to concrete and called as Steel Fiber Reinforced Concrete (SFRC). Similarly an important and most frequently

encountered combination of construction materials is that of steel and concrete, with applications in multi -storey commercial

buildings and factories, as well as in bridges. These materials can be used in mixed structural systems, for example concrete cores

encircled by steel tubes, as well as in composite structures where members consisting of steel and concrete act together

compositely. In present work, an experimental investigation on the structural behavior of encased steel concrete composite

columns was made. The percentage of steel fiber is varying by addition of different percentages of steel fiber such as 0.2, 0 .4,

0.6, 0.8 and 1. The material properties were tested and mechanical properties such as compressive strength, split tensile strength

and Flexure strength test are carried with M 40 mix proportions for CC. The addition of 1% of steel fiber shows good strength

performance in comparison with conventional concrete.

© 2015 Ishitv Technologies LLP All rights reserved.

Keywords: Self Fibre Reinforced Concrete,Compressive Strength

1. Introduction

Concrete is a widely used construction material for various types of structures due to its durability. For a

long time it was considered to be very durable material requiring a little or no maintenance. Many environmental

phenomena are known significantly the durability of reinforced Concrete structures. We build Concrete structures in

highly polluted urban and industrial areas, aggressive marine environments and many other hostile conditions where

other materials of construction are found to be nondurable. Concrete is a structural components exist in buildings

mailto:[email protected])b


54

and bridges in different forms. Understanding the response of these components during loading is crucial to the

development of an overall efficient and safe structure. Different methods have been utilized to study the response of

structural components. Experimental based testing has been widely used as a means to analyze individual elements

and the effects of Concrete strength under loading. It has now become the choice method to analyze Concrete

structural components.

Normal conventional Concrete members attain failure in some cases by the property tensile strength. Hence

it can be compensated by means of adding of different percentages of steel fibers with Concrete mixture provide us a

good strength and tensile property. More research works are carried out in the steel fiber reinforced Concrete with

addition of different fibers with different ratios. Steel Fiber-reinforced Concrete (SFRC) is Concrete containing

fibrous material which increases its structural integrity. It contains short discrete fibers that are uniformly distributed

and randomly oriented. In the last few years, many failures were occur in the reinforced Concrete structures and

their losses are very high under economical considerations. Fibers include steel fibers, glass fibers, synthetic fibers

and natural fibers. Within these different fibers that character of fiber reinforced Concrete changes with varying

Concretes, fiber materials, geometries, distribution, orientation and densities.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. The increase in compressive strength will enhance their strength in column. Steel

Fiber Reinforced Concrete is a Concrete mix that contains short, discrete fibers that are uniformly distributed and

randomly oriented. Fibers used are steel fibers, synthetic fibers, glass fibers, and natural fibers.The main function of

the fibers in members is that of resisting the opening of the cracks due to micro cracking, increasing the ability of

the member to with stand loads. The characteristic of fiber reinforced Concrete are changed by the alteration of

quantities of Concrete, fiber substances, geometric configuration, dispersal, direction and concentration. It is a

special type of Concrete in which cement based matrix is reinforced with ordered or random distribution of

fiber.The addition of fibers to the conventional Concrete is varying from 1-2% by volume depending on geometry of

fibers and type of application. The inclusion of steel fibers in Concrete is to delay and control tensile cracking of

composite material. It imparts extensive post cracking behavior and significantly enhances the ductility and energy

absorption capacity of the composite. This composite consists of one or more phases that are discontinuous

embedded in a continuous phase. Discontinuous phase is usually harder and stronger than the continuous phase and

is called as reinforcement or reinforcing material. The continuous phase is known as matrix.

2. Experimental Setup

Materials

Cement

https://en.wikipedia.org/wiki/Plasticity_(physics)

https://en.wikipedia.org/wiki/Permeability_(fluid)

https://en.wikipedia.org/wiki/Water


55

An Ordinary Portland cement of 53 grades was used for casting cubes, cylinders and Prism for Concrete

mixes. There are two intrinsic requirements for any cement in the Concrete mix design. The compressive strength

development with time and attainment of appropriate rheological characteristics type and production of Concrete.

Variation in the chemical composition and physical properties of cement affects the strength parameters. The Table

1 gives the properties of cement for OPC 53 Grade.

Table 1: Properties of Cement

Aggregate

Aggregate properties greatly influence the behavior of Concrete, since they occupy about 80% of the total

volume of Concrete. The aggregate are classified as

Fine aggregate : Fine aggregate are material passing through an IS sieve that is less than 4.75mm Gauge Usually

natural sand is used as a fine aggregate at places where natural sand is not available crushed stone is used as a fine

aggregate. The sand used for the experimental works was locally procured and conformed to grading zone II. Sieve

analysis of the fine Aggregate was carried out in the laboratory as per IS 383-1970 and shown in Table 2. The fine

aggregate was first sieved through 4.75mm sieve to remove any particle greater than 4.75 mm sieve and then was

washed to remove the dust.

Table 2: Properties of Fine Aggregate

Properties Test value Standard value

Type Natural sand Natural sand

Specific

gravity 2.60

2.3

Fineness

modulus 2.705

2.6-2.9

Properties Test value Standard value

Specific gravity 3.12 3.15

Normal

consistency 33%

30%

Initial setting 45 minutes 30 minutes

Fineness 8% <10%


56

Coarse aggregate: The materials which are retained on 4.75mm sieve are called coarse aggregate. The broken stone

is generally used as a coarse aggregate. The nature of work decides the maximum size of the coarse aggregate.

Locally available coarse aggregate having the maximum size of 10 mm was used in the present work. According to

IS 383:1970 coarse aggregate maximum 10 -20mm coarse aggregate is suitable for Concrete work and the properties

are shown in Table 3. But where there is no restriction 40mm or large size may be permitted.

Table 3: Properties of Coarse Aggregate

Properties Test value

Standard value

Type Crushed

Crushed

Specific gravity 2.83

2.5 – 2.8

Maximum size 20mm

20mm

Fineness

modulus 3.33

2.9-3.5

Water

Water is an important ingredient of Concrete as it actively participates in the chemical reaction with cement.

Since it helps to form the strength giving cement gel, the quantity and quality of water is required to be looked

into very carefully. Potable water is generally considered satisfactory. In the present investigation, tap water was

used for both mixing and curing purposes. As per codal provision, IS 456-2000 Ph value should me greater than

6.

Steel fiber

Steel fiber used in Concrete is basically a cheaper and easier to use form of rebar reinforced Concrete.

Rebar reinforced Concrete uses steel bars that are laid within the liquid cement, which requires a great deal of

preparation work but make for a much stronger Concrete. Steel fiber-reinforced Concrete uses thin steel wires

mixed in with the cement. This imparts the Concrete with greater structural strength, reduces cracking and helps

protect against extreme cold. Steel fiber is often used in conjunction with rebar or one of the other fiber types. The

properties of steel fiber are shown in Table 4.The steel fiber used in our investigation is with an aspect ratio (l/d)

of 50.


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Hooked end fiber has been in the market for over 25 years. This shape is probably the most popular and

successful in the history of steel fiber reinforced Concrete. HE can be used in almost any known application for

steel fiber reinforced Concrete. HE does not perform as well as undulated fibers with regard to shrinkage control

but it provides excellent workability when using fibers with up to an aspect ratio of 60. Aspect ratios up to and

including 80 provide satisfactory workability. HE can be used with any Concrete mix and high Concrete density

is less mandatory then for undulated or for flat-end fibers. Load transfer in the crack is very good with this fiber

shape. Fig 1 shows the pictorial view of steel Fiber. Thus after the appearance of the first crack the loss of load-

bearing capacity occurs quickly but then stabilizes and in some cases even begins to increase again after large

cracks have developed.

2.1 Fabrication of Sensing Pellet

Table 4: Properties of Steel Fiber

Properties Description

Cross section Hooked end

Diameter (d) 1mm

Length(L) 50mm

Density 7800 kg/cu.m

Young modulus 2 x 105 Mpa

Mix Proportion for M40 & SFRC Concrete


58

The mix proportions are made for M40 grade and its proportions are in the table for the conventional and SFRC

with different percentages of Steel Fiber. Thus addition of steel fiber to conventional with various percentages

show improving the strength of Concrete. Table 5, 6,7,8,9 & 10 gives the clear proportion of the Concrete mixes

used in our experimental work.

Table 5: Mix proportion of SFRC (0% of fiber) in M40 Grade Concrete

Specimen

Quantity of materials

Cement

(kg)

Fine

aggregate

(kg)

Coarse

aggregate

(kg)

Water

(liters)

Conventional

Concrete

637 1132 197

6.37

1 1.3 2.53

0.4

Table 6: Mix proportion of SFRC (0.2% of fiber) in M40 Grade Concrete

Specimen


Cement

(kg)

Fine

aggregate

(kg)

Coarse

aggregate

(kg)

Water

(liters)

Steel

fiber (%)

Steel Fiber

Reinforced

Concrete

(SFRC)

637 1132 197

6.37

0.20 1 1.3 2.53

0.4


Specimen


Cement

(kg)

Fine

aggregate

(kg)

Coarse

aggregate

(kg

Water

(liters)

Steel

fiber (%)

Steel Fiber

Reinforced 637 1132 197

6.37


59

Specimen


Cement

(kg)

Fine

aggregate

(kg)

Coarse

aggregate

(kg

Water

(liters)

Steel

fiber (%)

Concrete

(SFRC) 1 1.3 2.53

0.4

0.40


Specimen


Cement

(kg)

Fine

aggregate

(kg)

Coarse

aggregate

(kg)

Water

(liters)

Steel

fiber (%)

Steel Fiber

Reinforced

Concrete

(SFRC)

637 1132 197

6.37

0.60

1 1.3 2.53

0.4


Specimen


Cement

(kg)

Fine

aggregate

(kg)

Coarse

aggregate

(kg)

Water

(liters)

Steel

fiber (%)

Steel Fiber

Reinforced

Concrete

(SFRC)

637 1132 197

6.37

0.80

1 1.3 2.53

0.4

Table 10: Mix proportion of SFRC (1% of fiber) in M40 Grade Concrete


60

Specimen


Cement

(kg)

Fine

aggregate

(kg)

Coarse

aggregate

(kg)

Water

(liters)

Steel

fiber (%)

Steel Fiber

Reinforced

Concrete

(SFRC)

637 1132 197

6.37

1

1 1.3 2.53

0.4

III. PREPARATION OF SPECIMENS

The test specimens where cast in cast-iron moulds. The inside of the mould were applied with oil to facilitate the

easy removal of specimens. For obtaining the binder content sand and cement were mixed dry and kept separately.

Then coarse aggregates and dry mix of cement and sand were kept in three layers and approximate amount of water

was sprinkled on each layer and mixed thoroughly. The specimens casted with mix proportions of M40 grade by

weight with water cement ratios of 0.40. The materials were mixed in hand mixer. The Coarse aggregate and fine

aggregate were added and mixed thoroughly in a dry condition then cement and water added to get fresh Concrete

mix. Mixing of fiber reinforced Concrete needs careful conditions to avoid balling of fibers, segregation and in

general the difficulty of mixing the materials uniformly. Increase in the aspect ratio, volume percentage and size

and quantity of coarse aggregate intensify the difficulties and balling tendency. Steel fiber content of 1% by

volume and aspect ratio of 50 are made with M40 grade. Totally 54 cubes, cylinder and Prisms specimens were

casted and tested for 7 days, 14 days and 28 days to determine the strength of the conventional and SFRC by

compressive, split tensile and flexure test on Concrete.

Flexural Strength Test


61

Compressive strength of Cube specimens

Compressive strength of Concrete depends on many factors such as water-cement ratio, cement strength,

quality of Concrete material, and quality control during production of Concrete etc. Compressive strength is the

capacity of a material or structure to withstand axial loads tending to reduce size. When the limit of compressive

strength is reached, brittle materials are crushed. Concrete can be made to have high compressive strength and tested

as shown in figure 2. Cubes are prepared for conventional and SFRC. The size of the cube is 150 x 150 x 150 mm.

the failure load of compressive strength of cube is calculated by using the formula.

Compressive strength = Load/Area N/mm2

Split Tensile Strength of Concrete

The test is carried out by placing cylinder specimen of dimension 150mm diameter and 300mm length,

horizontally between the loading surface of compression testing machine and the load is applied until failure of the

cylinder along the vertical diameter as shown in figure 3. The failure load of the specimen is noted. The failure load

of tensile strength of cylinder is calculated by using the formula

Tensile strength= 2P / 3.14 DL N/mm2

Where, P- Failure loads of the specimen, D-Diameter of the specimen and L-Length of specimen

Flexural Test for Prism

The test is carried out to find the flexural strength of the prism of dimension 100 mm x 100 mm x 500 mm as shown

in figure 4. The prism is then placed in the machine then load is applied to the uppermost surface as cast in the

mould. The load is applied until the failure of the prism. By using the failure load of prism,

Flexural strength = PL/bd2 N/mm2 Where – Failure load of the prism, L- Length of the prism, B-breadth of the prism

& D-depth of the prism.

Flexural strength = PL/bd2 N/mm2 Where – Failure load of the prism, L- Length of the prism, B-breadth of the prism

& D-depth of the prism.


62

Figure 4: Test for Flexural Strength

Results and Discussion

A. Compressive Strength of M 40 & SFRC with different percentages of fibers Volume.

The compressive strength of conventional Concrete and different percentages of steel fiber reinforced

Concrete are casted with tested and the results shows that for 7 days,14 days and 28days the strength achieved in

conventional Concrete is 20.53 N/mm2, 30.52 N/mm2 and 43.22 N/mm2 .The SFRC with 0.2% of steel fiber added

with the conventional Concrete obtained strength at 7 days ,14 days and 28days are 21.08 N/mm2,32.46 N/mm2 and

41.02 N/mm2.Similarly for the Concrete with addition of steel fiber with 0.4 % steel fiber induce strength 22.36

N/mm2, 31.54 N/mm2 and 41.38N/mm2. For the 0.6% addition of steel fiber shows strength such as 21.30 N/mm2,

32.94 N/mm2 and 43.04 N/mm2. The addition of 0.8 % of steel fiber in Concrete induces strength 24.42N/mm2,

33.42N/mm2 and 43.03N/mm2. The 1% percentage of steel fiber in Concrete achieves strength such as 25.84 N/mm2,

34.82 N/mm2 and 45.72N.mm2. From the tested results as shown in Table11 and figure 5, 1% of steel fiber have

higher compressive strength and good ductility in Concrete. About 54 cube specimens were casted and they are

tested in Compression Testing Machine by placing horizontally.

Table 11: Compressive strength of M 40 & SFRC with different percentages of fibers Volume

Specimen

No of

specimens

Compressive Strength(N/mm2)

7 Days

(N/mm2)

14 days

(N/mm2)

28

days(N/mm2)


63

CC(M40) 3 20.53 30.52 43.22

SFRC

(0.2%) 3 21.08 32.46 41.02

SFRC

(0.4%) 3 22.36 31.54 41.38

SFRC

(0.6%) 3 21.30 32.92 42.26

SFRC

(0.8%) 3 24.42 33.42 43.04

SFRC (1%) 3 25.84 34.82 45.72

Figure 5 : Compressive strength of M 40 & SFRC with different percentages of fibers Volume

B. Split Tensile strength of M 40 & SFRC with different percentages of fibers Volume.

The Split Tensile strength of conventional Concrete and different percentages of steel fiber reinforced Concrete are

tested and the results shows that for 7 days,14 days and 28days the strength achieved in conventional Concrete is

2.12 N/mm2, 2.96 N/mm2 and 3.81 N/mm2 .

The SFRC with 0.2% of steel fiber added with the conventional Concrete obtained strength at 7 days,14 days and

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er…

Stee

l Fib

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er…

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Compressive strength of M 40 &

SFRC with different percentages

of fibers Volume

Average Compressive

Strength

7 days

14 days

28 days


64

28days are 2.36 N/mm2, 3.24 N/mm2 and 3.90N/mm2.Similarly for the Concrete with addition of steel fiber with 0.4

% steel fiber induce strength 2.21 N/mm2, 3.36 N/mm2 and 4.02 N/mm2. For the 0.6% addition of steel fiber shows

strength such as 2.40 N/mm2, 3.34 N/mm2 and 4.36 N/mm2.The addition of 0.8 % of steel fiber in Concrete induces

strength 2.46 N/mm2, 3.42 N/mm2 and 4.48 N/mm2. The 1% percentage of steel fiber in Concrete achieves strength

such as 2.54 N/mm 2, 3.4 N/mm2 and 4.62N.mm2. From the tested results as shown in Table 12 and figure 6, 1% of

steel fibers have higher Split Tensile strength in Concrete. About 54 cylindrical specimens were casted and they are

tested in Compression Testing Machine.

Table 12: Split strength of M 40 & SFRC with different percentages of fibers Volume.

Specimen

No of

specimens

Split strength (N/mm2)

7 Days

(N/mm2)

14 days

(N/mm2)

28

days(N/mm2)

CC(M40) 3 2.12 2.96 3.81

SFRC

(0.2%)

3 2.36 3.24 3.90

SFRC

(0.4%)

3 2.21 3.36 4.02

SFRC

(0.6%)

3 2.40 3.34 4.36

SFRC

(0.8%)

3 2.46 3.42 4.48

SFRC (1%) 3 2.54 3.4 4.62


65

Figure 6 Split tensile strength of M 40 & SFRC with different percentages of fibers Volume

C. Flexural strength of M 40 & SFRC with different percentages of fibers Volume

The Flexural strength of conventional Concrete and different percentages of steel fiber reinforced Concrete 4. the

results shows that for 7 days,14 days and 28days the strength achieved in conventional Concrete is N/mm2, 2.96

N/mm2 and 3.81 N/mm2 .The SFRC with 0.2% of steel fiber added with the conventional Concrete obtained

strength at 7 days,14 days and 28days are 2.36 N/mm2, 3.24 N/mm2 and 3.90N/mm2.Similarly for the Concrete with

addition of steel fiber with 0.4 % steel fiber induce strength 2.21 N/mm2, 3.36 N/mm2 and 4.02 N/mm2. For the

0.6% addition of steel fiber shows strength such as 2.40 N/mm2, 3.34 N/mm2 and 4.36 N/mm2.The addition of 0.8 %

of steel fiber in Concrete induces strength 2.46 N/mm2, 3.42 N/mm2 and 4.48 N/mm2. The 1% percentage of steel

fiber in Concrete achieves strength such as 2.54 N/mm 2, 3.4 N/mm2 and 4.62N.mm2. From the tested results it

shown in Table 13 and figure 7, 1% of steel fiber have higher flexural strength in Concrete. About 54 prism

specimens were casted and they are tested in flexure Testing Machine under two point loading.

Table 13: Flexural strength of M 40 & SFRC with different percentages of fibers Volume

Specimen

No of

specimens

Flexural strength (N/mm2)

7 Days

(N/mm2)

14 days

(N/mm2)

28

days(N/m

m2)

CC(M40) 3 2.34 6.08 8.03

SFRC

(0.2%)

3 3.06 6.60 10.20

SFRC

(0.4%)

3 3.44 6.84 11.46

012345

Co

nve

nti

…

Stee

l…

Stee

l…

Stee

l…

Stee

l…

Stee

l…

Sp

lit

ten

sile

str

ength

(Nm

m2

)

Split strength of M 40 & SFRC with

different percentages of fibers …

Average Split tensile strength

7days


66

SFRC

(0.6%)

3 3.67 7.08 11.74

SFRC

(0.8%)

3 3.73 7.46 12.65

SFRC (1%) 3 3.90 7.72 13.78

Figure 7 Flexural strength of M 40 & SFRC with different percentages of fibers Volume

Conclusions

For the present study we determine the properties of the conventional Concrete with M40 grade and SFRC

(Steel Fiber Reinforced Concrete) with addition of different percentages of steel fiber were done. The physical

properties such as specific gravity and fineness modules are studied for cement, fine aggregate and coarse aggregate.

The mechanical properties such as compressive strength, Flexural strength and Split Tensile Strength were

found in accordance with Concrete specimens such as conventional and SFRC with (0.2%.0.4%, 0.6%

0.8% and 1%) of steel fiber in addition to the Concrete.

From the experimental results it shows the addition of 1% of steel fiber shows high strength both in

compression, split tensile and flexural strength.

From our observations it is found that, compressive strength increases 6 percentage strength in Steel fiber

reinforced Concrete with 1% of steel fiber in comparison with Conventional Concrete respectively.

From our observations it is found that, split tensile strength increases 3 percentage strength in Steel Fiber

Reinforced Concrete with 1% of steel fiber in comparison with Conventional Concrete respectively.

From our observations it is found that, the flexural strength increases 8 percentage strength in Steel Fiber

Reinforced Concrete with 1% of steel fiber in comparison with Conventional Concrete respectively.

0

5

10

15C

on

ve…

Stee

l…

Stee

l…

Stee

l…

Stee

l…

Stee

l…

Fle

xtu

ral

Str

en

gth

(N/m

m2)

Flexural strength of M 40 & SFRC

with different percentages of …

Average Flextural Strength

7 days

14 days

28 days


67

From the graph it shows the percentage of strength increasing in addition of steel fiber with 1% percentage

in comparison with conventional Concrete.range of humidity (10% to 80% of RH). CuO nanoparticle showed the

sensing response for a humidity sensor.

References [1] Amit Rana (2013) “Some Studies on Steel Fiber Reinforced Concrete”, International Journal of Emerging

Technology and Advanced Engineering”, ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 3, Issue

1, January, pp.120-128.

[2] Arnon Bentur & Sidney Mindess, „„ Fibre reinforced cementitious composites‟‟ Elsevier applied science

London and Newyork 1990.

[3] Balendran R.V., Zhou F.P, A. Nadeem, A.Y.T. Leung, “Influence of Steel Fibres on Strength and Ductility of

Normal and Lightweight High Strength Concrete”, Building and Environment, Vol.37, No.12, (2002), pp.

1361-1367.

Documents

EXPERIMENTAL INVESTIGATION ON BEHAVIOUR OF SFRC ON …ishitvtech.in/pdf/sajet-vol-3-no7-7.pdf · Concrete is a structural components exist in buildings . South Asian Journal of Engineering