1.

INTRODUCTION

1.1 GENERAL

The use of rubber product is increasing every year in worldwide. Waste tires are
major environmental problem for many metropolitan areas in the India. There are
more than 1 billion scrap tires, approximately one tire per person, generated each year
in the India. Currently 75-80% of scrap tyres are buried in landfills. Burying scrap
tyres in landfills is not only wasteful, but also costly. So many recycling methods for
the rubber tyre are carried according to the need. From this one of the processes is to
making the tyre rubber in to crumb and chipped rubber. This crumb and chipped
waste tires are different to other wastes materials with a potential for re-use because
there production method is now well developed, the reuse of this material in concrete
could have both environmental advantage and at the same time ensure economic
viability with improvement the characteristic design properties of concrete mix. It is
used in many works such as road construction, light weight construction, flooring,
mold making etc. in the form of rubcrete concrete.

The history of the cementing material is as old as the history of engineering

construction. Concrete is one of the most widely used construction material today.
More than 90% of the structures ranging from building, bridges, roads, dams,
retaining walls etc. utilize the concrete for their construction. The versatility and
mould ability of this material, its high compressive strength and discovery of
reinforcing and prestressing technique has gained its widespread use. This is the
popular construction material where strength, durability, impermeability, fire
resistance and abrasion resistance are required. Strength, durability, and workability
may be considered as main properties of concrete. In addition, good concrete should
be able to resist wear and corrosion and it should be water-tight, and economical. The
concrete must be strong enough to withstand without injury all the imposed stresses
with the required strength if properly placed in position and cured. After placing,
concrete should not be allowed to dry rapidly because moisture is very much essential

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for the development for its high strength. To develop a given strength, longer time of
moist curing is required at lower temperature than is neccessary while curing is done
at higher temperature.

Concrete is a homogeneous mixture of binder (cement), fine aggregates, coarse

aggregates and water in some specified proportion. The properties of concrete in
plastic state/ hardened state are dependent on the properties and the type of
ingredients used. So in order to get the required type of concrete quality, it is
necessary to control the properties of the ingredient materials. A thorough knowledge
of interaction of various knowledge of interaction of various ingredients of concrete is
required to be known to manufacture a concrete with stipulated characteristics.
Concrete is very good in compression but week in tension. Concrete can be made
durable by using good quality of materials i.e. Cement aggregates and water, by using
adequate quantity of cement and low water-content ratio thereby ensuring concrete of
increased impermeability. In addition, thorough mixing, desired placing, adequate
compaction and curing of the concrete is equally important to have durable concrete.

Modifications of construction materials have an important bearing on the building

sector. Several attempts have been therefore made in the building material industry to
put to use waste material products, e.g., worn-out tyres, into useful and cost effective
items. Success in this regard will contribute to the reduction of waste material
dumping problems by utilizing the waste materials as raw materials for other
products. The waste problem considered as one of the most crucial problems facing
the world as a source of the environmental pollution. It is contributing as a direct
form in pollution that includes the negative effects on the health by increasing the
diseases, disease vector, percentage of mortality and lowering the standard of living.
The waste usually defined as the all remains things resulted from production, transfer
and uses processes, and in general all transmitted things and resources that the owner
or the producer wants to dispose or must dispose to prevent the risk on the health of
the human and save the environment in general.

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The proposed work presents an experimental study of effect of use of solid waste
material (crumb rubber) in concrete by volume variation of crumb rubber. One of the
important types of remains is waste tyres which have been classified as a part of
municipal solid waste (MSW), resulted from the increase of vehicle ownership. This
eventually will increase consumption of tyres over time. Current practices show that
residents throw it randomly in different places such as valleys, road sides, open areas
and waste dumpsites in improper ways taking the means of open fire, and without
consideration of risk on human health and environment.

Fig.1.1 Used tyre waste in an open area (www.google.com[3])

Fig.1.2 Waste tyre dump on fire (www.google.com[3])

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 2. MATERIAL CHARACTERISTICS

Scrap tyres can be managed as a whole tyre, a slit tyre, a shredded or chipped tyre, as
ground rubber or crumb rubber product.

2.1 Whole Tyres

A typical scrapped automobile tyre weighs 9.1 kg and composed of 35% natural
rubber and 65% synthetic rubber. Steel-belted radial tyres are the predominant type of
tyre currently produced. A typical truck tyre weighs 18.2kg and also contains from 60
to 70 % recoverable rubber. Truck tyres typically contain 65% natural rubber and
35% synthetic rubber. Although a majority of truck tyres are steel-belted radials, there
are still a number of bias ply truck tyres, which contain either Nylon or polyester belt
material.

2.3 Slit Tyres

Slit tyres are produced in tyre cutting machines. These cutting machines can slit the
tyre into two halves or can separate the sidewalls from the tread of the tyre.

2.3 Crumb Rubber

Crumb rubber may be produced by mechanical grinding (ambient process) or by

cryogenic process (freezing). In the mechanical process, tyres are reduced to chips or
shreds and then put through granulators which separate and remove loose steel and
fiber and further reduce rubber particle size. Finally, the small rubber chunks are
ground to produce rubber crumb of 30 to 80 mesh size. In the cryogenic process, tyre
chips are frozen in liquid nitrogen as they pass through a cryogenic tunnel then
broken down by impact. They then pass through a series of screen meshes where they
are shattered into their three component parts: rubber, steel and fabric. Although the
cryogenic process is the more expensive of the two, it produces smoother and smaller
crumb.

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 Fig.2.1. Crumb Rubber (www.google.com[3])

2.4 Shredded or Chipped Tyres

In most cases the production of tyre shreds or tyre chips involves primary and
secondary shredding. A tyre shredder is a machine with a series of oscillating or
reciprocating cutting edges, moving back and forth in opposite directions, that
effectively cuts or shreds tyres as they are fed into the machine. The size of the tyre
shreds produced in the primary shredding process can vary from as large as 300 to
460mm long by 100 to 230mm as wide, down to as small as 100 to 150mm in length,
depending on the manufacturer, model, and condition of the cutting edges. Production
of tyre chips, which are generally sized from 76mm to 13mm, requires two-stage
processing of the tyre shreds to achieve adequate size reduction. Secondary shredding
results in the production of chips that are more equidimensional than the larger size
shreds that are generated by the primary shredder.

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 Fig.2.2. Typical shredding waste tyre machine (Sangeeta Dhyani, 2017[7])

2.5 Ground Rubber

Ground rubber may be sized from particles as large as 19mm to as fine as 0.15mm
depending on the type of size reduction equipment and the intended application. The
production of ground rubber is achieved by granulators, hammer mills, or fine
grinding machines. Granulators typically produce particles that are regularly shaped
and cubical with a comparatively low surface area.

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 3. MANUFACTURING OF CRUMB RUBBER

Crumb rubber is made by combination or application of several size reduction

technologies. These technologies may be divided into two major processing
categories, mechanical grinding and cryogenic reduction.

3.1 Mechanical Grinding

Mechanical grinding is the most commonly used process. The method consists of
mechanically breaking down the rubber into small particles using a variety of
grinding techniques, such as cracker mills, granulators etc. the steel components are
removed by a magnetic separator. The fiber components are separated by air
classifiers. These systems are well established and can produce crumb rubber at
relatively low cost. The system is easy to maintain and requires few people to operate
and service. Replacement parts are generally easy to obtain and install. The other
important advantage of mechanical grinding relates to the shape and physical
properties of the crumb rubber particles. The shape and surface texture of the crumb
rubber particles are relatively rounded and smooth, and are able to form molecular
cross-links with virgin rubber material. The rubber materials are broken down under
high shear stress. Since the tyre compound consists of a carbon-sulphur cross linked
matrix, the grinding process causes ‘de-linking’ of the material. The resulting ‘de-
linked’ material is more viscous compared to virgin rubber and is a unique
characteristic of mechanically ground crumb rubber. For applications involving
compounding with virgin rubber or plastic, crumb rubber provides some
advantageous attributes to the visco elastic compound. The crumb rubbers do not
cause a deterioration of tensile strength at low to moderate loading.

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3.2 Cryogenics

The cryogenics process consists of freezing the shredded rubber at an extremely low
temperature. The frozen rubber compound is then easily shattered into small particles.
The fiber and steel are removed in the same fashion as in mechanical grinding. The
advantages of the system are cleaner and faster operation resulting in the production
of fine mesh size. The most significant disadvantage is the slightly higher cost due to
the added of cooling.

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 4. RUBCRETE

The concrete mixed with waste rubber added in different volume proportions is called
rubcrete concrete. Partially replacing the coarse or fine aggregate of concrete with
some quantity of small waste tire in the form of crumb and chipped can improve
qualities such as low unit weight, high resistance to abrasion, absorbing the shocks
and vibrations, high ductility and brittleness and so on to the concrete.

4.1 MATERIALS

The primary materials are cement, fine aggregate, course aggregate, water, chemical
admixtures and rubber.

4.1.1 Cement

Cement is one of the basic construction materials that will be generally in powdered
form and hardens upon the addition of water to it. It can serve as a binding material to
aggregates to obtain strength. It possesses cohesive and adhesive properties. The
chemical composition of the cements can be quite diverse but by far the greatest
amount of concrete used today is made with Portland cements. For this reason, the
discussion of cement in this report is mainly about the Portland cement.
Portland cement, the basic ingredient of concrete, is a closely controlled chemical
combination of calcium, silicon, aluminum, iron and small amounts of other
ingredients to which gypsum is added in the final grinding process to regulate the
setting time of the concrete. Lime and silica make up about 85% of the mass.
Common among the materials used in its manufacture are limestone, shells, and chalk
or marl combined with shale, clay. Generally, its Specific Gravity is 3.15.

4.1.2 Fine Aggregate

Fine Aggregate is a filling material for the Concrete. The Fine Aggregate used for this
study is River Sand. The Aggregate passing through IS: 4.75 mm sieve could be

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called as Fine Aggregate. Generally, The Specific Gravity of Fine Aggregate is 2.4 to
2.6.

4.1.3 Coarse Aggregate

The aggregate passing through IS: 20 mm sieve and retained on IS: 4.75mm sieve
could be called as coarse aggregate. Generally, Coarse aggregate is a material that
enhances the strength and stability for the concrete. The coarse aggregate used for this
study is from Miyapur Quarry. The specific gravity of fine aggregate is 2.4 to 2.6.

4.1.4 Water

Water is a key ingredient in the manufacture of concrete. Attention should be given to

the quality of water used in concrete. Mixing water can cause problems by
introducing impurities that have a detrimental effect on concrete quality. Although
satisfactory strength development is of primary concern, impurities contained in the
mix water may also affect setting times, drying shrinkage, or durability or they may
cause efflorescence. Water should be avoided if it contains large amounts of
dissolved solids, or appreciable amounts of organic materials.

4.1.5 Chemical Admixtures

Admixtures are ingredients other than water, aggregates, hydraulic cement, and fibers
that are added to the concrete batch immediately before or during mixing. A proper
use of admixtures offers certain beneficial effects to concrete, including improved
quality, acceleration or retardation of setting time, enhanced frost and sulfate
resistance, control of strength development, improved workability, and enhanced
finish ability.

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4.1.6 Rubber

Rubber is an inorganic material that is obtained from latex collected from tapped
rubber trees. It has a property to compress and is a ductile material. The rubber used
for this study is scrap tyre of 20mm thick and 100mm diameter, from IDA Jeedimetla,
cut into 20mm size pieces. Generally, the specific gravity of rubber is 1.52.

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 5. APPLICATION OF RUBCRETE CONCRETE

 In non-load bearing members as lightweight concrete walls.

 In highway constructions as a shock absorber.
 In sound barriers as a sound absorber.
 In buildings as an earthquake shock-wave absorber.
 It may also used in runways and taxiways in the airport, industrial floorings
and even as structural member.

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 6. EXPERIMENTAL STUDY

6.1 CONCRETE MIX DESIGN

For this study, we have adopted concrete grade of M30. The Mix Design for these
grade are done as per IS 10262-1982.

Table 6.1 Details of M30 Mix Proportion

Water Cement Fine Aggregate Coarse Aggregate

191.58 kg/ m3 456.142 kg/ m3 337.5003 kg/ m3 1147.91521 kg/ m3

6.2 CASTING OF SPECIMEN

The mixing of concrete is done to have a homogeneous mixture of all ingredients in

concrete including crumb rubber. The mixing of ingredients was done in the concrete
mixer. The known quantities of fine aggregate were replaced by crumb rubber like
5%, 10 %. Required quantity of water was added in dry mixture of cement, sand,
coarse aggregate and crumb rubber. They were mixed vigorously till the resulting mix
become homogeneous and uniform in appearance. Rotating drum type batch mixer
was used for mixing the concrete ingredient. Before each batching the mixer was
cleaned and washed with the fresh water so that there should not be any chemical
agent adheres to it which could have used before.

Fig.6.1. Rotating drum type mixer (Sangeeta Dhyani, 2017[7])

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6.3 TESTING OF SPECIMEN

Structural performance of the concrete mainly depends upon its strength in

compression and flexure so it is essential to carry out tests to determine these
properties. The following tests was carried out on concrete and summarized as below:

 Compression Strength
 Split Tensile Strength

6.3.1 Compression strength

Compressive strength test were carried out on 150mm×150mm×150mm cubes with

compression testing machine of 2000KN capacity. The specimen, after removal from
curing tank was cleaned and dried. The surface of the testing machine was cleaned.
The specimen was placed at the centre of the compression testing machine and load
was applied continuously, uniformly and without shocks and the rate of loading was
14N/mm2/minute i.e. at constant rate of stress. The load was increased until the
specimen failed. The maximum load taken by each specimen during the test was
recorded. The compressive strength was found after 7 and 28 days in order to
compare the strengths for different percentage of fibers in concrete.

Fig.6.2. Compression strength test (Sangeeta Dhyani, 2017[7])

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6.3.2 Split tensile strength

A standard test cylinder of concrete specimen (300mm×150mm diameter) is placed

horizontally between loading surfaces of compression testing machine. The
compression load is applied diametrically and uniformly along the length of cylinder
until the failure of cylinder along the vertical diameter. To allow the uniform
distribution of this applied load and to reduce the magnitude of high compressive
stresses near the point of application of this load, strips of plywood are placed
between the specimen and loading platens of the testing machine. Concrete cylinders
split into two halves along this vertical plane due to indirect tensile stress generated
by poisson’s effect.

Fig.6.3. Split tensile strength test (Sangeeta Dhyani, 2017[7])

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6.4 RESULTS

The tests results to show concrete behavior will change as a result of the volumetric
replacement of sand with crumb waste tyres.

6.4.1 Compression strength test result

Table 6.4.1 Test Results of M30 Grade Compression Strength

Compression strength
(N/mm2)
Sl no Percentage of
rubber
7th day 14th day 28th day

1 0 37.73 41.51 44.62

2 5 33.24 35.9 42.17

3 10 31.2 34.8 36.4

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6.4.2 Split tensile strength test result

Table 6.4.2 Test Results of M30 Grade Split Tensile Strength

Spilt Tensile Strength Values

(KN)
Sl no Percentage of
rubber
7th day 14th day 28th day

1 0 450 505 539

2 5 443 496 528

3 10 439 489 504

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 7. FUTURE SCOPE OF STUDY

The present work was undertaken to study the investigation on crumb rubber
modified concrete by replacing up to 10% of fine aggregate with crumb rubber.
However, further studies may be planned to cover the following aspects particularly
of rubberized concrete.

 Durability and plastic shrinkage of rubberized concrete.

 Properties of fresh concrete and hardened concrete with tyre chips of different
size as an addition to the concrete rather than its replacement with aggregates.
 Effect of surface texture of rubber particles and effect of different curing
methods on rubberized concrete.
 Effects of size of crumb rubber on behavior of modified concrete.
 The combination of two different types of fiber such as crumb rubber and
steel fiber may tend to provide better performance.
 Effects of volume variation of crumb rubber on concrete when more than 20%
sand is replaced by crumb rubber.
 Properties of hardened modified concrete with different curing periods.
 Effects on the properties of the hardened modified concrete with different
types of loading.
 Properties of the self compacting rubberized concrete.
 Effects of different water cement ratios with different aspect ratio of
aggregates on the properties of rubberized concrete.
 Durability of rubberized concrete under freeze thaw cycles.
 Fire performance of rubberized concrete.
 Effect of crumb rubber in asphaltic applications.

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 8. CONCLUSIONS

The test results of this study indicate that there is great potential for the utilization of
waste tyres in concrete mixes in several percentages, ranging from 0% to 10%. Based
on present study, the following can be concluded.

 The strength of modified concrete is reduced with an increase in the rubber

content, however lower unit weight meets the criteria of light weight concrete
that fulfill the strength requirements.
 Concrete with higher percentage of crumb rubber possess high toughness. The
slump of the modified concrete increases about 1.08%, with the use of 1 to 5%
of crumb rubber.
 Energy generated in the modified concrete is mainly plastic.
 Stress strain shows that concrete with a higher percentage of crumb rubber
possess high toughness, since the generated energy is mainly plastic.
 Failure of plain and rubberized concrete in compression and spilt tension
shows that rubberized concrete has higher toughness.
 The spilt tensile strength of the concrete decreases about 30% when 20% sand
is replaced by crumb rubber.
 The flexural strength of the concrete decreases about 69% when 20% sand is
replaced by crumb rubber.
 The compressive strength of the concrete decreases about 37% when 20%
sand is replaced by crumb rubber.
 For large percentage of crumb rubber the compressive strength gain rate is
lower than that of plain concrete.

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Journal of Management, Technology And Engineering , Volume 8, Issue XI,
pp 508-516
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R (2017) Experimental Investigation on Replacement of Course Aggregate by
Shredded Rubber Tyre, International Journal of Chem Tech Research,
2017,10(8), pp 670-676.
3. www.google.com
4. R Santhosh Kumar, N Manodeepan, K Manikandan, S Prabhavathi and S
Arulkesavan (2015) An Experimental Investigation on Rubberized
Concrete,International Journal for Innovative Research in Science &
Technology, Volume 2, Issue 07, pp 82-88.
5. G. Nagesh Kumar, V. Sandeep and Ch. Sudharani (2014) Using Tyres
Wastes as Aggregates in Concrete to Form Rubcrete – Mix for Engineering
Applications, International Journal of Research in Engineering and
Technology, Volume 03, Issue 11, pp 500-509.
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Shinde (2016) Use of waste tyres in road construction, International Research
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Rubber, International Journal of Research in Technology and Management,
Volume 3, Issue 3, pp 17-19.
8. Mazyad Al-Fadhli (2017) Advantages of Concrete Mixing with Tyre Rubber,
Int. Journal of Engineering Research and Application, Volume 7, Issue 4,
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