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Experimental Studies on Composite Precast
Roof Panels under Static Flexure
Vasudevan N1
PG Student1,M.E Structural Engineering,
Department of civil engineering,
PSNA College of Engineering and Technology,
Dindigul, Tamil Nadu, India.
RanjithBabu B2
Assistant professor2
Department of civil engineering
PSNA College of engineering and technology
Dindigul, Tamil Nadu, India.
Abstract - Prefabricated composite roof
panels offer a variety of possibilities to be used in
many locations where economy, ease of
construction and speed are of prime importance.
High strength to weight ratio, reduced weight and
thereby attraction of lesser seismic forces and good
thermal insulation are some of the important
characteristics of the panels. Use of light-weight
structural elements in buildings is becoming
popular in the recent years. The sand is replaced
with copper slag with various percentage
0,25,50,75,100.The compression, spilt tensile and
rebound hammer tests were conducted for cubes
and cylinder with varying percentage of copper
slag. Therefore the slabs were casted with 0, 25, 50,
75&100 percentage replacement of copper slag. In
this study the flexural behaviour of precast light-
weight concrete panels under four-point bending is
observed and the variable parameter such as
replacement of copper slag has been studied
Keywords - Precast, Sandwich Panels,
Light-Weight Panels, Copper Slag, Expanded
Polystyrene.
1.INTRODUCTION
Precast concrete structural elements are
manufactured under controlled factory conditions
and therefore concrete structural elements with
good precision in geometry and finishing can be
manufactured. Background information on precast
technology can be found in the literature. Precast
concrete elements besides being structurally and
economically efficient, also have social and
environmental benefits. Precast structural elements
if light-weighted also have advantages such as (i)
less attraction of seismic forces, (ii) ease of
handling and transportation and (iii) cost effective.
Light-weight concrete sandwich panels produced
by replacing core concrete using lesser dense
material consist of two skins of concrete called
wythe, one on either side of the core. Welded wire
mesh or conventional steel rebars may be used to
reinforce the wythes. The core is made of material
that provides significant thermal and sound
insulation. In this study, EPS (Expanded
Polystyrene) is used as the core. In order to achieve
composite action of the panel under flexural load
shear transfer between the two wythes is ensured
by using shear connectors that connect the two
wythes. Experimental studies on the behaviour of
light-weight concrete sandwich panels under
different load conditions can be found in the
literature which have proved the feasibility of using
these panels for floors, roofs and walls of the
buildings. Nevertheless, it is noted that in the
literature no studies are found reported on the
flexural behaviour of light-weight concrete
sandwich panels with wires as shear connectors. In
this paper the results of the experimental study
carried out to determine the flexural behaviour of
prototype precast light-weight concrete sandwich
panels with wires as shear connectors under four-
point bending are presented. Four prototype panels
are tested in the present study to study the effect of
percentage of reinforcement in wythes and the total
thickness of the panel, both of which are directly
proportional to the moment carrying capacity,
ultimate load carrying capacity and the flexural
behaviour of light-weight concrete sandwich panel.
The paper is organized as follows. Section 2
presents the materials used and casting of the
panels, Section 3 presents the experimental work
test set-up details, Section 4 presents the results and
discussions and Section 5 presents summary and
conclusions.
II. MATERIALS DETAILS
2.1 Cement
Cement is largely dependent binder
material in concrete and its quality production must
be ensured with little or no hazard to the
environment. India is one of the largest producers
of cement. For this experimental investigation
RAMCO 53 grade ordinary Portland cement is
used. Specific Gravity of Cement is 3.1.finess of
cement 0.28%.
2.2 Fine aggregate
Sand is an inert occurring material of size
less than 4.75 mm. Specific gravity of fine
aggregate 2.6. Fineness Modulus of Fine Aggregate
= 2.75.
2.3 Coarse aggregate
As explained fine aggregate used for
concrete production is classified as fine aggregate
and coarse aggregate depending on its particle size.
Aggregate of size more than 4.75 mm, is called as
coarse aggregate and is one of the most important
ingredient of concrete. It gives strength to the
concrete and constitutes about 70 to 75 percent
volume of concrete. Crushed stone in general used
as coarse aggregate which is black in colour,
angular and in local name known as black metal. Specific gravity of coarse aggregate is 2.72. Bulk
Density of Coarse Aggregate is1527 kg / m3 Fineness Modulus of Coarse Aggregate is 3.24
2.4 Water
Potable water conforming to the
Requirements of water for concreting and curing as
per IS: 456 2000.
2.5 Copper slag
Copper slag is a by-product material
produced from the process of manufacturing
copper. As the copper settles down in the smelter, it
has a higher density, impurities stay in the top layer
and then are transported to a water basin with a low
temperature for solidification. The end product is a
solid, hard material that goes to the crusher for
further processing. Copper slag used in this work
was brought from Oman Mining Company, which
produces an annual average of 60,000 tons. The
physical properties of copper slag is given in table
.It is an industrial by-product material produced
during the copper smelting and refining process of
manufacturing of copper which can be used for a
surprising number of applications in the building
and industrial fields. This material represents a
popular alternative to sand as a blasting medium in
industrial cleaning. Using blasting or high-pressure
spraying techniques, companies are using copper
slag to clean large smelting equipment or furnaces
.Material like copper slag can be used as one which
can reduce the cost of construction
Physical Properties
Particle shape Irregular
Appearance Black & glassy
Type Air cooled
Specific gravity 3.91.3.68
Percentage of voids 43.20%
Bulk density 2.08g/cc, 1.70 to
1.90 g /cc
Fineness modulus of copper
size 3.47
Angle of internal friction 510 200
Particle size 0.075mm to 4.75
mm
Hardness Between 6 and 7
2.6 Expanded Polystyrene
EPS is a closed cell lightweight cellular
plastics material produced from polystyrene. The
material has been modified by the addition of flame
retardant additives. Polystyrene literally translated
is “polymerised styrene”. That is, the single styrene
molecules are chemically joined together to form a
large molecule which is called the polymer. Styrene
is produced from benzene and ethylene, and
polymerisation is accomplished in the presence of
catalysts, usually organic peroxides. The
expandable form is produced as small beads
containing a blowing agent.
2.7 MIX PROPORTIONS
In this study the copper slag was replaced
instead of fine aggregate with various percentage as
25, 50, 75,100. For M30grade of concrete mix
design was done as per IS: 10262-2009.
2.8 MIX RATIO
III. EXPERIMENTAL WORK
The experimental program includes
preparation and testing of Five slabs with different
proportions of sand by replacing them by copper
slag under four point loading.
3.1 Raw Materials used
Raw materials like Portland cement, fine
aggregate that passes through the 2.36mm sieve,
coarse aggregate 12.5mm,wire mesh with 3mm
diameter and cross section 50mm x 50 mm, sand is
replaced by percentage of 0,25,50,75&100 copper
slag.
Cement
Fine
aggregate
Coarse
aggregate
W/ C ratio
1 1.43 2.33 0.45
3.2 Preparation of Mould
Mould made up of steel, concrete or wood
can be used. Considering the economical condition
wooden mould are used. wooden mould of
dimension 1.3m x 0.5m x 0.075 m is constructed to
obtain a roof panel of required size for the
construction of the precast panel. After hardened
the precast panels are demoulded from the wooden
mould and is undergone for curing.
3.3 Preparation of Mix
Cement, fine aggregate and coarse
aggregate with the ratio of 1:1.43:2.33 is measured
, taken and undergone to normal hand mixing.
Initially dry mix preparation is done and later on
water and mixed together to give flowability to the
mix.
3.4 Casting of specimen
The wooden mould is placed in the plane
surface and the concrete mix poured for 1/3 from
the mould thickness and binded wire mesh and EPS
is placed at the centre of the mould then once again
the concrete is poured in to the mould and let leave
it for hardening.
3.5 curing
Specimens are cast and demoulded after 1
day and then allowed to cure for 28 days. The slabs
were laid to rest vertically in position.
3.6 Testing of slabs
The slab panels were removed from curing
after a period of 28 days. White wash was applied
to the panels in order to get clear indication of
cracks due to bending under service loads. Panels
were tested for flexural strength under universal
testing machine. The panels were placed on support
leaving a space of 50 mm from both ends. Dial
gauge was placed below the panel to record the
deflection in mm each stage of loading. Cracks are
then marked during each loading and
corresponding central deflection is also noted
down.
IV. RESULTS AND DISCUSSIONS
4.1 COMPRESSIVE STRENGTH TEST (28 DAYS)
4.2 SPLIT TENSILE TEST(28DAYS)
TESTING PROCEDURE
Flexure testing is carried out in universal testing machine of 1000tonne capacity.
4.1 Flexural strength on slab
S.NO MIX CS 0 CS 25 CS 50 CS 75 CS 100
1 1:1.43:2.33 5 kN 6.5 kN 8 kN 7 kN 5.5 kN
4.1 TEST RESULTS AND DISCUSSION
• The observed ultimate load for cracking of ratio
1:1.43:2.33 for Slab are 5 KN, 6.5 KN, 8 KN, 7KN
and 5.5 KN for CS 0, CS 25, CS 50 , CS 75 & CS
100.
• The number of cracks developed in slab at first
cracking is 4.5, 6, 7.5,6.5 and 5 for ratio
1:1.43:2.33
• The crack spacing at ultimate load for slab are
45mm, 71mm, 127mm, 97mm and 77mm
respectively for the Static Loading.
• Finally the observation concludes that the
Flexural Behaviour of slab has gained more
strength with mix ratio 1:1.43:2.33
29.4 26.137.6 36.2
30.1
0% 25% 50% 75% 100%
COMPRESSIVE STRENGTH
(MPa)COMPRESSVE STRENGTH
2.33 2.372.79 2.54
2.05
0% 25% 50% 75% 100%
SPILT TENSILE STRENGTH
(MPa)
spilt tensile test
CASTING AND TESTING
4.3 Load–deflection profile for panels
5. ACKNOWLEDGEMENTS
Authors are grateful to the Civil
Engineering Department for their help in
conducting this project and acknowledge the
management of PSNA College of Engineering And
Technology for their moral support.
REFERENCES:
[1] Beatrice Belletti, Patrizia Bernardi, Elena
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[3] Daniel Ronald Joseph J, Prabakar J,
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EISSN: 2321-9637.
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DEFLECTION
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LOAD VS DEFLECTION
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