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Partial replacement of discarded rubber tyres with coarse aggregate
ABSTRACT
The disposal of waste tyres is becoming a major waste management problem in the world at the
moment. It is estimated that 1.2 billions of waste tyre rubber produced globally in a year. It is estimated
that 11% of postconsumer tyres are exported and 27% are sent to landfill, stockpiled or dumped illegally
and only 4% is used for civil engineering projects. Hence efforts have been taken to identify the
potential application of waste tyres in civil engineering projects. In this essence, our present study aims
to investigate the optimal use of waste tyre rubber crumbs as coarse aggregate in concrete composite.
A total of 6 cubes are casted of M25 grade by replacing 20 percent of tyre aggregate with coarse
aggregate and compared with regular M25 grade concrete. Fresh and hardened concretesuch as
workability, compressive strength were identified.
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Partial replacement of discarded rubber tyres with coarse aggregate
Introdution:
The scarcity and availability at reasonable rates of sand and aggregates lead to invent the new
materials with their replacement. The new materials should not be much expensive than what we have
now or else it would be somewhat again cannot be replaceable because every cannot use it. The material
should be economical and affordably available.
So, from number of years the experiments have been going on to replace partially or completely
by the solid wastes which cannot harm the construction and gives same strength as the regular
aggregate.
Discarded rubber tyres, plastic waste, rice husk, fly ash etc, are some of the waste materials can
partially replaced by the coarse or fine aggregate. The rubber aggregate from discarded tyre rubber is
one of the waste material which can be used to partially replace natural aggregate in sizes 20-10mm, 10-
4.75mm and 4.75 down can be partially replaced.
About one crore ten lakhs all types of new vehicles are added each year to the Indian roads. The
increase of about three crores discarded tyres. The disposal of which each year pose a potential threat to
environment.
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Partial replacement of discarded rubber tyres with coarse aggregate
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Partial replacement of discarded rubber tyres with coarse aggregate
Materials:
Rubber aggregate:Rubber aggregate of 20mm are taken from lorry tyres of MRF make partially replacing the coarse
aggregate of concrete with some quantity of small waste tyre material. These materials are cut into
20mm size manually. The research has shown that material improves qualities such as low unit weight,
high resistance to abrasion, absorbing the shocks and vibrations and so on to the concrete more over
inclusion of rubber in to concrete results in higher durability and elasticity.
Discarded tyres as concrete aggregates:Earlier studies in the use of worn-out tyres in asphalt mixes were very promising, they showed that
rubberized asphalt had better skid resistance, reduced fatigue cracking and achieved longer pavement
life than conventional asphalt. So far very little work have been done in the use of rubber from scrap
tyres in Portland cement concrete mixture. The work done so far in the use of tyre rubber as aggregate
in concrete is given below.
Slump:It was observed slump decreases with increase rubber content by total aggregates volume, the results
show that at rubber content 20% by total aggregates volume. The slump was normal and the concrete
was workable. This mix was properly compacted because rubber having low unit weight and low
interlocking capacity without proper mixing rubber cannot paired up with the concrete as natural
aggregate.
Density: The general density reduction was to be expected due to the low specific gravity of the rubber
aggregates with respect to that of the natural aggregates. The reduction in density can be a desirable
feature in a number of application, including architectural application such as nailing concrete, false
facades, stone backing and interior construction as well as precast concrete, light weight hollow and
solid blocks, slabs etc.
Air content:The air content increases in rubber concrete mixture with increase amount of ground tyre rubber.
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Partial replacement of discarded rubber tyres with coarse aggregate
Plastic shrinkage:The addition of rubber shreds to mortar reduced plastic shrinkage cracking compared to a control
mortar. Despite their apparently weak bonding to the cement paste, rubber shreds provided sufficient
restrain to prevent micro cracks from propagating.
Effect of surface texture of rubber particles:Various studies show that the rougher the rubber particles used in concrete mixtures the better the
bonding they develop with the surrounding matrix and, therefore, the higher the compressive strength of
rubber concrete may be obtained by improving the bond between rubber particles and the surrounding
cement paste. Pretreatment to improve bond of rubber aggregates vary from merely washing them with
water to acid etching. The treatment increase in surface roughness of the rubber, which improves its
attachment to the cement paste. Upon loading weak bonding of rubber aggregates to surrounding cement
paste is one of the main cause of lower compressive strerngth of rubber concrete. There are various
methods by which rubber aggregates bonds may be improved. The waste rubber recycling factories
should supply the rubber aggregates in pretreated and specified gradings for their better performance.
This will build confidence to users and improve the mass sale of rubber aggregates as a new
construction material of cement concrete construction. Quality rubber aggregates should be
manufactured and supplied by waste rubber recycling factories in grading 20-10 mm, 10-4.75 mm and
4.75 mm down sizes.
Toughness, impact resistance, heat and sound insulation: Rubberized concrete has ability to with stand large tensile deformations, the rubber particles act as
springs, delaying the widening of cracks and preventing full disintegration of the concrete mass.
Rubberized concrete will give better performance than conventional concrete where vibration damping
is required, such as in building as an earthquakes shock-wave absorber, in foundation pads for
machinery, and in Railway stations.
When rubber aggregates were added to the mixture, the impact resistance of concrete is increased,
Rubber aggregates in concreter also make the material a better thermal insulator, which could be very
useful especially in the wake of energy conservation requirements. From fire test it was observed that
flammability of rubber in rubber concrete mixture was much reduced by the presence of cement and
aggregates. It is believed that fire resistance of rubber concrete mixture is satisfactory. In this connection
more testing is needed.
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Partial replacement of discarded rubber tyres with coarse aggregate
Coarse aggregate:Coarse aggregate of angular shape 20mm and 10mm sizes are mixed to increase the interlocking
capacity. The most desirable fine-aggregate grading depends on the type of work, the richness of the
mixture, and the maximum size of coarse aggregate. In leaner mixtures, or when small-size coarse
aggregates are used, a grading that approaches the maximum recommended percentage passing each
sieve is desirable for workability. In general, if the water-cement ratio is kept constant and the ratio of
fine-to-coarse aggregate is chosen correctly, a wide range in grading can be used without measurable
effect on strength. However, the best economy will sometimes be achieved by adjusting the concrete
mixture to suit the gradation of the local aggregates.
Type of material: 20mm c.a
Wt. of sample taken for testing: 2kg
IS sieve wt.of aggregate retained pecentage retained cumulative % retained % passing
observed As per IS-38340mm 0 0 0 100 10020mm 0.22 11 11 89 85-10010mm 1.63 81.5 92.5 7.5 0-204.75mm 0.15 7.5 100 0 0-5
Type of material: 10mm c.a
Wt. of sample taken for testing: 1kg
IS sieve wt.of aggregate retained pecentage retained cumulative % retained % passing
observed As per IS-38312.5mm 0 0 0 100 10010mm 0.1 10 10 90 85-1004.75mm 0.8 80 90 10 0-202.36mm 0.1 10 100 0 0-5
Fine aggregate:
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Partial replacement of discarded rubber tyres with coarse aggregate
The shape surface texture, angularity and grading of the fine aggregate used in Portland cement concrete
mixtures significantly effect the workability, strength and performance of the concrete mixtures in
service. Shape,surface texture, angularity are the results of the interaction of the nature, structure, and
texture of the rock of which the particles consist and the forces to which they were subjected during and
after formation of the particles.
1.when rock is crushed it generally breaks along the inter faces between the mineral crystals making up
the rock.this is where the binding is weakest.
2.it is difficult to produce particles having a cubical shape from astrong homogeneous rock such as fine
graned trap rock (or) basalt. Homogeneous rock trends to disintegrate into flakes. Sedimentary rocks
commonly are laminated and the strength of the material is lower in one direction than in others.
3.the rock tends to form slabby particles. Rock having closely spaced partings (or) cleavages in one of
two directions produce flat or elongated particles.
Type of material: sand fine aggregate
wt. of sample taken for testing: 0.5kg
IS sieve wt.of aggregate retained pecentage retained cumulative % retained % passing
observed As per IS-38310mm 0 0 0 100 1004.75mm 0.017 3.4 3.4 96.6 90-1002.36mm 0.021 4.2 7.6 92.4 75-1001.18mm 0.066 13.2 20.8 79.2 55-90600micron 0.201 40.2 61 39 35-59300micron 0.104 20.8 81.8 18.2 80-30150micron 0.091 18.2 100 0 0-10
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Partial replacement of discarded rubber tyres with coarse aggregate
Portland pozolana cement(ppc of 43 grade)
The Portland Pozzolana Cement is a kind of Blended Cement which is produced by either intergrinding
of OPC clinker along with gypsum and pozzolanic materials in certain proportions or grinding the OPC
clinker, gypsum and Pozzolanic materials separately and thoroughly blending them in certain
proportions.
Pozzolana is a natural or artificial material containing silica in a reactive form. It may be further
discussed as siliceous or siliceous and aluminous material which in itself possesses little, or no
cementitious properties but will in finely divided form and in the presence of moisture, chemically react
with calcium hydroxide at ordinary temperature.
M25 concrete mix design with partial replacement of rubber
Stipulations for proportioning:
Grade designation – m25
Type of cement – pcc 43grade
Maxmimum nominal aggregate size – 20mm
Minimum cement concrete – 280kg/m3
Maximum water cement ratio – 0.5
Workability – 25mm to 50mm
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Partial replacement of discarded rubber tyres with coarse aggregate
Exposure condition – extreme
Type of aggregate – crushed angular aggregate
Maximum cement content -445.58kg/m3
Replacement of rubber aggregate – crushed square aggregate
Test data for materials:
Cement used - ppc 43grade
Specific gravity of cement – 3.15
Specific gravity of water – 1.00
Specific gravity of 20mm aggregate – 2.6
Specific gravity of 20mm rubber aggregate – 1.14
Specific gravity of a sand – 2.6
Target strength for mix proportions:
Target mean strength = fck + 1.65*standard deviation
Where fck characteristics strength at 28days = 25n/mm2
Fck = fck + 1.65* standard deviation =24+1.65*4
=31.6n/mm2
Selection of water cement concrete:
From graph of relation between free water cement ratio and concrete strength for different cement strength. The water cement ratio required for target mean strength of 31.6n/mm2 is 0.5.
Adopt water content is 0.50
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Partial replacement of discarded rubber tyres with coarse aggregate
Selection of water content: selection of w/c from curves
For 20mm maximum size aggregate
sand conforming to grading zone 11
water content per cubic metre of concrete = 186kg
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Partial replacement of discarded rubber tyres with coarse aggregate
sand content as percentage of total aggregate by obsolute volume = 35%
adjustment is regular.
change in condition percent adjustment water content required sand in total aggregatefor decrease in water cement ratio by (0. 0 -1(0.60-0.50) that is 0.10for increase in compacting factor 3 0(0.9-0.8) i.e, 0.1for sand conforming to zone 3 of 0 -1.5table 4, IS 383 - 1970
TOTAL 3 -2.5
Therefore required sand content as percentage of total aggregate by absolute volume
= 35 – 4.9
= 30.1%
Required water content
= 186 + 5.58
=191.6 l/m3
Determination of cement content:
Water cement ratio = 0.45
Water = 191.6
Cement = 191.6/0.45
= 445.58 kg/m3
Determination of coarse and fine aggregate contents:
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Partial replacement of discarded rubber tyres with coarse aggregate
0.98 = [191.6 + 445.58/3.15 + 1/0.301 * fa/2.6] *1/1000
0.98 = [191.6 + 141.45 + 1.277fa] * 1/1000
980 = 333.05 + 1.277fa
fa = 506.61 kg/m3
ca = (1-0.301/0.301) * 506.61 * (2.6/2.6)
ca = 1101.67 kg/m3
The mix proportions has become:
cement fine aggregate coarse aggregate445.58 506.61 1101.67
1 1.13 2.47
For one cube of size 150mm*150mm*150mm
Fine aggregate=1.709kg
Coarse aggregate=3.718kg
Cement=1.5kg
Rubber aggregate=0.32kg
Coarse aggregate=2.96kg
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Partial replacement of discarded rubber tyres with coarse aggregate
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Partial replacement of discarded rubber tyres with coarse aggregate
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Partial replacement of discarded rubber tyres with coarse aggregate
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Partial replacement of discarded rubber tyres with coarse aggregate
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Partial replacement of discarded rubber tyres with coarse aggregate
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Partial replacement of discarded rubber tyres with coarse aggregate
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