International Journal of Engineering Trends and Technology (IJETT) – Volume1 Issue3 – June 2011
Experimental Study Of Light Weight Concrete By The Partial
Replacement Of Coarse Aggregate By Thermo Plastics
Saritha .B1,J.Chamundeeswari2
1,2
Assistant Professor
Department of Civil Engineering, Bharath University
173, Agaram Road, Selaiyur, Tambaram,Chennai-73,India.
Abstract
In this project work we had done an experimental study on the light weight concrete (using plastic
aggregates) and the conventional concrete which is an ordinary concrete. In this project work we had
done concrete mix design in the M20 grade. We had replaced the coarse aggregate partially by the plastic
aggregates (in the light weight concrete) which are having the properties of the thermoplastics. We got
these aggregates from the MS plastics (company name) located at sedharapet in Pondicherry. We partially
replaced (thirty percent) the coarse aggregate in the concrete by this plastic aggregate which is having the
properties of the thermoplastics. We had conducted the concrete tests on both conventional concrete and
on the light weight concrete. Finally we had an comparative study on both these conventional concrete
and light weight concrete.
Keywords: Light weight concrete,thermoplastic,compressive strength,rebound testultra pulse value
test,tension, test,flexure test
1. Introduction
Concrete is a composite construction material composed primaril of aggregate, cement and water. There
are many formulations that have varied properties. The aggregate is generally a coarse gravel or crushed
rocks such as limestone, or granite, along with a fine aggregate such as sand. The cement, commonly
Portland cement, and other cementitious materials such as fly ash and slag cement, serve as a binder for
the aggregate. Various chemical admixtures are also added to achieve varied properties. Water is then
mixed with this dry composite which enables it to be shaped (typically poured) and then solidified and
hardened into rock-hard strength through achemical process known as hydration. The water reacts with
the cement which bonds the other components together, eventually creating a robust stone-like material.
Concrete has relatively high compressive strength,but much lower tensile strength. For this reason is
usually reinforced with materials that are strongi n tension (often steel). Concrete can be damaged by
many processes,such as the freezing of trapped water.
Concreteis widely used for making architectural structures, foundations, brick/block walls,pavements,
bridges/overpasses, motorways/roads, runways, parking structures, dams, pools/reservoirs, pipes,
footings for gates, fences and poles and even boats. Famous concrete structures include the BurjKhalifa
(world's tallest building), the Hoover Dam, the Panama Canal and the Roman Pantheon.
Concrete technology was known by the Ancient Romans and was widely used within the Roman Empire.
After the Empire passed, use of concrete became scarce until the technology was re-pioneered in the mid18th century.
1.1 light weight concrete
The majority of regular concrete produced is in the density range of 150 pounds per cubic
foot (pcf). The last decade has seen great strides in the realm of dense concrete and fantastic
compressive strengths (up to 20,000 psi) which mix designers have achieved. Yet regular
concrete has some drawbacks. It is heavy, hard to work with, and after it sets, one cannot cut or
nail into it without some difficulty or use of special tools. Some complaints about it include the
perception that it is cold and damp. Still, it is a remarkable building material - fluid, strong,
relatively cheap, and environmentally innocuous. And, it is available in almost every part of the
world. Regular concrete with microscopic air bubbles added up to 7% is called air entrained concrete. It is
generally used for increasing the workability of wet concrete and reducing the freeze-thaw damage by
making it less permeable to water absorption.Conventional air entrainment admixtures, while providing
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International Journal of Engineering Trends and Technology (IJETT) – Volume1 Issue3 – June 2011
relatively stable air in small quantities, have a limited range of application and aren't well suited for
specialty lightweight mix designs. Lightweight concrete begins in the density range of less than 120 pcf.
It has traditionally been made using such aggregates as expanded shale, clay, vermiculite, pumice, and
scoria among others. Each have their peculiarities in handling, especially the volcanic aggregates which
need careful moisture monitoring and are difficult to pump. Decreasing the weight and density
produces significant changes which improves many properties of concrete, both in placement
and application. Although this has been accomplished primarily through the use of lightweight
aggregates, since 1928 various preformed foams have been added to mixes, further reducing
weight. The very lightest mixes (from 20 to 60 pcf) are often made using only foam as the
aggregate, and are referred to as cellular concrete. The entrapped air takes the form of small,
macroscopic, spherically shaped bubbles uniformly dispersed in the concrete mix. Today foams
are available which have a high degree of compatibility with many of the admixtures currently
used in modern concrete mix designs. Gecko Stone of Hawaii is currently experimenting with
one such foam.
Foam used with either lightweight aggregates and/or admixtures such as fly ash, silica fume, synthetic
fiber reinforcement, and high range water reducers (aka superplasticizers), has produced a new hybrid of
concrete called lightweight composite concrete, or LWC.
For the most part, implementation of Lightweight Composite design and construction utilizes existing
technology. Its uniqueness, however, is the novel combination drawing from several fields at once:
architecture, mix design chemistry, structural engineering, and concrete placement.
Given the hoops that any new material or method must go through, implementation of LWC construction
can be much at the mercy of any number of bureaucratic standards (licenses, approvals, etc.) including
fire ratings, material test data, environmental impacts, as well as opposition from labor unions and
existing suppliers supporting the lumber industry.
Bureaucratic standards are sometimes easy enough to achieve, but only if one has deep pockets. But these
costs are pretty much out of range for the average entrepreneurs in this field. These individuals also have
found reluctance within the ready mix industry to take the initiative for R&D... their natural conservatism
and relative success in the last four decades only has reinforced their will to keep things the same without
added risk.
They wait for the entrepreneur's homework. Other technologies, such as synthetic fiber manufacturers,
also wait for the entrepreneur. It seems leadership, unfortunately, is not likely to come from the industries
with the most available resources, but from those individuals who not only have a vision for the future,
but a persistent mission to make it a reality.
2. Materials and Methods
2.1Collection of materials
The materials required for this project are coarse aggregate, fine aggregate, ordinary Portland cement, for
the conventional concrete and plastic aggregate, fine aggregate, and ordinary Portland cement for the light
weight aggregate concrete.
We collected the fine aggregate, coarse aggregate and ordinary Portland cement from the places near by
our college campus.
We collected the plastic aggregate made by thermoplastic from the msplastics(company name) located at
sedharapet in Pondicherry.Nearlywecollected60kgof this plastic aggregate on that available place. The
price of the 1kg of this plastic aggregate is 55 rupees.
2.2 Testng of materials
The testing of materials can be classified under the following categories They are
a ) Tests on cement
b ) Tests on fine aggregate
c ) Tests on coarse aggregate
2.2.1 Tests on cement
o Finess of cement
o Normal consistency of cement
o Intial setting time of cement
o Final setting time of cement
o Specific gravity
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International Journal of Engineering Trends and Technology (IJETT) – Volume1 Issue3 – June 2011
2.2.2 Tests on fine aggregate
o Sieve analysis
o Specific gravity
o Water absorption
2.2.3 Tests on coarse aggregate
o Impact test
o Loss angles test
o Attribution test
o Crushing value
o Sieve analysis
o Water absorption
2.3 Mix Design
In this project work our aim is to get the mix design of grade M20 (1:1.5:3). For that mix design we are
following the procedures from the IS-code book.
2.4 Casting of Concrete Specimen
After finishing the mix design and testing of the materials we are going to cast the cubes, cylinders and
beams in both the conventional concrete and also in the light weight concrete (using plastic aggregates).
We are going to cast 18 cubes, 18 cylinders and 18 beams. On these 18 cubes, 9 cubes for
the conventional concrete and 9 cubes for the light weight concrete, on the 18 cylinders, 9
cylinders for the conventional concrete and 9 cylinders for the light weight concrete, on the 18
beams, 9 beams for the conventional concrete and 9 beams for the light weight concrete.
2.5 Testing of Concrete Specimen
The tests for the concrete specimen can be classified as under the following conditions. They are,
o Tests on fresh concrete
o Tests on hardened concrete
2.5.1 Tests on fresh concrete
o Slump test
o Vee-bee consistometer
o Compaction value
2.5.2 Tests on hardened concrete
o Compression test
o Flexure test
o Rebound hammer test
2.5.3 Design Mix proportion
WATER
188.79
0.525
CEMENT
359.6 Kg
1
FINE AGGRAGATE
591.97 Kg
1.65
COARSE AGGREGATE
1202.08 Kg
3.34
3. Results and Discussion
This tests are classified into following categories. There are,
a )Tests on materials
b ) Tests on fresh concrete
c )Tests on hardened concrete
3.1 Tests on materials
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International Journal of Engineering Trends and Technology (IJETT) – Volume1 Issue3 – June 2011
a) Fineness of cement
The fineness index of the given cement sample is 2.68%
b) Normal consistency of cement
The normal consistency of cement paste is found to be 36%
c) Initial setting time
The initial setting time of the given sample of cement is 28 minutes.
d) Specific gravity of cement
The specific gravity of given sample of cement is 3.2
c) Specific gravity
The specific gravity of the given coarse aggregate is 2.67
The specific gravity of the given fine aggregate is 2.61
d) Water absorption
The water absorption for the given coarse aggregate is 0.5%
The water absorption for the given fine aggregate is 1.04%.
e) Crushing test
The crushing value for coarse aggregate sample is 25.23%.
The crushing value for the thermoplastic aggregate is 0.986
f) Impact test
The impact value of the coarse aggregate sample is found to be 23.65%.
The impact value of the thermoplastic aggregate sample is found to be 2.85%
3.2 Tests on fresh concrete
a) Slump test
The slump value of the conventional concrete having the water cement ratio of 0.525 is 17mm.
The slump value of the light weight concrete having the water cement ratio of 0.525 is
9mm.
b) Compaction factor of freshly mixed concrete
The compacting factor for the conventional concrete mix is 0.826
The compacting factor for the light weight concrete mix is 0.773
3.3 Tests on hardened concrete
Table 1 Tests conducted after 7 days
Specimen
Tests
Ordinary concrete
cubes
Ultra pulse value test (m/s) 4411
Rebound test (N/mm2)
26
Compression
strength 23.55
2
(N/mm )
Cylinders
33
Rebound test (N/mm2)
2
Tension test (N/mm )
2.49
Ultra pulse value test(m/s) 4385
Beams
27
Rebound test (N/mm2)
2
Flexure test (N/mm )
36
Light weight concrete
4225
24
20.44
31
2.22
4032
26
34.5
Table 2Tests conducted after 14 days
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International Journal of Engineering Trends and Technology (IJETT) – Volume1 Issue3 – June 2011
Specimen
Tests
cubes
Ultra pulse value test (m/s)
2
Rebound test (N/mm )
Compression
(N/mm2)
Cylinders
Light weight concrete
4504
4373
28
26
strength 27.77
Rebound test (N/mm2)
23.22
34
32
Tension test (N/mm )
3.3
2.77
Ultra pulse value test(m/s)
4665
3257
Rebound test (N/mm2)
28
27
42
37
2
Beams
Ordinary concrete
2
Flexure test (N/mm )
Table 3 Tests conducted after 28 days
Specimen
cubes
Tests
Ultra pulse value test (m/s)
2
Rebound test (N/mm )
Compression
(N/mm2)
Cylinders
Light weight concrete
4716
4424
30
28
strength 31.23
Rebound test (N/mm2)
28.45
36
35
Tension test (N/mm )
3.34
3.19
Ultra pulse value test(m/s)
4444
4366
Rebound test (N/mm2)
30
29
52
44
2
Beams
Ordinary concrete
2
Flexure test (N/mm )
4. Conclusion
The compressive strength of the partially light weight concrete is lower than the ordinary
conventional concrete. Therefore this light weight concrete will be used in the places where the structure
is not belonging to any external force. This light weight concrete is only capable to carry its self weight
only.
The workability of the light weight concrete is not good when it is compared to the ordinary
conventional concrete. This workability can be improved by introducing microscopic air bubbles into this
concrete.
Also the flexure strength, tensile strength values of the partially light weight concrete are lower
than the ordinary conventional concrete. So this light weight aggregate will be used in the places where
the external forces are not applied in the structure.
The partially light weight concrete may also be used as structural concrete on some cases
because it is having the compressive strength value which is suitable for structural (greater than
17.44N/mm2).
Reference
ISSN: 2231-5381
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International Journal of Engineering Trends and Technology (IJETT) – Volume1 Issue3 – June 2011
1. Chandra, S. and Berntsson, L. Lightweight aggregate concrete: science, technology and applications.
Noyes Publications.
2. Berra, M. and Ferrara, G. “Normal weight and total-lightweight high-strength concretes: A comparative
experimental study,” SP-121, 1990, pp.701-733.
3. Kayali, O.A. and Haque, M.N. “A new generation of structural lightweight concrete,” ACI, SP-171,
1997, pp. 569-588.
4. Bai, Y. and Basheer, P.A.M. “Influence of Furnace Bottom Ash on properties of concrete,” Proceedings
of the Institution of Civil Engineers, Structure and Buildings 156, February 2003, Issue 1, pp. 85-92.
5. Bai, Y. and Basheer, P.A.M. “Properties of concrete containing Furnace Bottom Ash as a sand
replacement material,” Proceedings of structural faults and repairCD-ROM), London, July 1-3,
2003.
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