FVFD

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Mix Design and Performance Assessment
Of Crumb Rubber Modified Bitumen
Submitted By
Name: Mir Sayed Ekram
Roll No: 200101037
Sap ID:100004875
Under The Supervisor
Dr. Subhojit Roy
Assistant Professor Department of Civil
Engineering
Dehradun, Uttarakhand, India

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CONTENT
1. Mix Design and Performance Assessment Of Crumb Rubber Modified Bitumen.
2. INTRODUCTION
3. Types of Modified Bitumen
4. What is crumb Rubber
5. Rubber Case
6. Effect of Temperature on Natural Rubber
7. Advantages of Crumb Rubber
8. Desirable Properties of Bituminous Mix
9. Literature Review
10.Objective of Study
11. Selection of Materials
15. Properties of Mix
16. Theoretical Specific of The Mix Gt
17. Air Voids Percent Vv
18. Percent Volume of Bitumen Vb

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19. Voids in mineral aggregate VMA
20. Voids filled with bitumen VFB
21. Experimental Studies
22. Experiment 1. : To determine the specific gravity and water absorption of aggregate.
23. Experiment 2. : To find out the stripping value of the road aggregates

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INTRODUCTION
• India has a road network of over 4,689,842 kilometers in 2013 , and the
second largest road network in the world. It has primarily flexible pavement
design which constitutes more than 98% of the total road network.
• India being a very fast country has widely varying climates, terrains,
construction materials and mixed traffic conditions both in terms of loads
and volumes. Increased traffic factors such as heavier loads, higher traffic
volume and higher tyre pressure demand higher performance pavements.
• So to minimize the damage of pavement surface and increase durability of
flexible pavement, the conventional bitumen needs to be improved.

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• There are many modification processes and additives that are
currently used in bitumen modifications such as
1) Styrene butadiene styrene (SBS)
2) Styrene-butadiene rubber (SBR)
3) Ethylene vinyl acetate (EVA)
4) Crumb rubber modifier (CRM).
Types of Modified Bitumen

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What is crumb Rubber
• Crumb rubber is the term usually applied to recycled rubber from
automotive and truck scrap tires. During the cycling process steel and
fluff is removed leaving tire rubber with a granular consistency.
• And continued processing with a granulator and/or cracker machine,
possibly with the help of mechanical means, like reduces the size of
the particles From physical and chemical interaction of crumb rubber
with conventional bitumen Crumb Rubber Modified Bitumen (CRMB)
is made it.

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Crumb Rubber

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Rubber
• Rubber is derived from tyre which is a complex and high-tech safety
product representing a century of manufacturing innovation, which is
still on-going From the material point of view.
• Tyre is made up of three main components materials:
1) elastomeric compound
2) fabric
3) steel

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Collecting Rubber From tyre by the help of grinder

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Effect of Temperature on Natural Rubber
A. At -10 degree C brittle and opaque
B. At 20 degree C soft, resilient and translucent
C. At 50 degree C plastic and sticky
D. At 120 degree C & -160 degree C vulcanized when agents like
sulphur are added
E. At 180 degree C break down as in the masticator
F. At 200 degree C decomposes.

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Advantages of Crumb Rubber
• Lower susceptibility to daily & seasonal temperature variations
• Higher resistance to deformation at elevated pavement temperature
• Better age resistance properties
• Higher fatigue life of mixes
• Better adhesion between aggregate & binder
• Prevention of cracking & reflective cracking
• Overall improved performance in extreme climatic conditions & under
heavy traffic condition.

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Desirable Properties of Bituminous Mix
• Adequate stability of the mix to withstand the stresses and deformation
due to the repeated application of the wheel loads; this may be achieved
by selecting suitable type and gradation of aggregates, appropriate binder
and its proportion.
• Adequate flexibility of the mix to withstand fatigue effects and
development of cracks during service life of the pavement to be achieved
by the selection of proper mix of aggregates and binder.
• Adequate resistance to permanent deformation such as rutting due to
movement of heavy wheel loads during hot weather; this may be achieved
by selection of good quality of aggregates, ensuring its appropriate
gradation and densification of the mix during compaction.

13. Literature Review
• A number of studies are available on topic of –CRUMB ROBBER
MODIFIED BITUMEN.
• Hence a detailed review of research works carried out related to the
present study is described as below.
• Investigations in India and countries abroad have revealed that
properties of bitumen and bituminous mixes can be improved to
meet requirements of pavement with the incorporation of certain
additives or blend of additives.
• These additives called “MODIFIER BITUMEN” and the bitumen
premixed with these modifiers is known as modified bitumen.

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• Modified bitumen is expected to give higher life of surfacing (up to
100%) depending upon degree of modification and type of additives and
modification process used.
• The additive used in our current study is Crumb Rubber and Use of
crumb rubber as an additive to the conventional mixes leads to
excellent pavement life, driving comfort and low maintenance.
• So, The rheology of CRMB depends on internal factors such as crumb
rubber quantity, type, particle size, source and pure bitumen
composition, and external factors such as the mixing time, temperature,
and also the mixing process (dry process or wet process).

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PROCESS OF CUTTING TYRE BY USING BASIC AVAILABILITIES
a) b)

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c) d)

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MODIFIED CRUMB RUBBER
MODIFIED CRUMB RUBBER
e)

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Objective of Study
• Preparation of Crumb Rubber Modified Bituminous Mix by varying
percentage of crumb rubber with bitumen
• Identifying the optimum crumb-rubber modified bitumen percentage
in mix design using Marshall Stability Test

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Selection of Materials
a) Selection of aggregates
• Aggregates which possess sufficient strength, hardness, toughness, soundness and
polished stone value are chosen, keeping in view the availability.
• Crushed aggregates and sharp sand produce high stability of the mix when compared
with gravel and rounded sands.
a) Selection of aggregate grading
• The properties of a bituminous mix including the density and stability are very much
dependent on the aggregates and their grain size distribution.
• Most of the engineering organizations have specified the use of dense graded mixes
and not open graded mixes. As higher maximum size of aggregates gives higher
stability, usually the larger size that can be adopted depends on the compacted
thickness of the pavement layer. Maximum aggregate size of 25 to 50 mm are used
in the bituminous mixes for base course and 12.5 to 18.7 mm are used for surface
course.

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a) Selection of Crumb Rubber
a) Selection of Bitumen
MODIFIED CRUMB RUBBER
BITUMEN

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Calculation test using Marshall Stability
Test
(As per IS 17127: 2019)

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Rubber % Bitumen (gm) Rubber (gm)
10% 75.6 8.4
20% 67.2 16.8
30% 58.8 25.2
Experiment: 3.5% Binder
• Aggregate = 1200 gm per sample
• Number of samples = 8
• Normal Bitumen = 84 gm
Crumb Rubber Modified Bitumen Calculations:
Binder Content Calculations (CRMB Mix Design using
Marshall Stability Test)
• Total Bitumen = 285.6 gm
• Total Rubber = 50.4 gm
• Total Aggregate = 9600 gm

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Rubber % Bitumen (gm) Rubber (gm)
10% 86.4 9.6
20% 76.8 19.2
30% 67.2 28.8
Experiment: 4.0% Binder
• Aggregate = 1200 gm per sample
• Number of samples = 8
• Normal Bitumen = 96 gm
Crumb Rubber Modified Bitumen Calculations:
• Total Bitumen = 326.4 gm
• Total Rubber = 57.6 gm
• Total Aggregate = 9600 gm

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Rubber % Bitumen (gm) Rubber (gm)
10% 97.2 10.8
20% 86.4 21.6
30% 75.6 32.4
Experiment: 4.5% Binder
• Aggregate = 1200 gm per sample
• Number of samples = 8
• Normal Bitumen = 108 gm
Crumb Rubber Modified Bitumen Calculations:
• Total Bitumen = 367.2 gm
• Total Rubber = 64.8 gm
• Total Aggregate = 9600 gm

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Theoretical Specific Gravity of the mix (GT): without rubber
Formula:
Where,
W1= Weight of course aggregate.
W2= Weight of filler, dust
Wb= Weight of bitumen Specific
G1= Specific Gravity course aggregate
=2.6
G2= Specific Gravity of filler =2.4
• G3= Specific Gravity of bitumen =1.09

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For 3.5% Binder
W1= 264+276+240 =780 gm
W2= 420 gm
Wb= 42 gm
=
Sample.1 Gt1= 2.42
Sample2 Gt2= 2.42
For 4% Binder
Sample.1 Gt1= 2.4
Sample2 Gt2= 2.4

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For 4.5% Binder
Gt1………………………Sample 1
• Gt2

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Mixer Asphalt Mixer

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Compaction mix design bitumen

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A) B)

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A) B)
C)

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Marshal stability test report

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Bulk Specific gravity of mix (Gm):
Formula:
Where,
Wa= w.t of sample in air
Ww= w.t of sample in water
For 3.5% Binder
=1.39
=1.48

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For 4% Binder
=1.44
=1.53
For 4.5% Binder
=1.46
• =1.45

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Bulk Density:
Formula:
For 3.5% Binder
=14.07 KN/m3
For 4% Binder
=14.56 KN/m3
For 4.5% Binder
• =14.27 KN/m3

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Betumen Content
%
Bulk Density Gravity Bulk Density
Sample 1 Sample 2 Average
3.5% 1.39 1.48 1.435 14.07
4% 1.44 1.53 1.485 14.56
4.5% 1.46 1.45 1.455 14.27
Bulk Density Table:

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4% 4% 5%
14.4
14.45
14.5
14.55
14.6
14.65
14.7
14.75
Bulk density
Bitumen Content
Bulk
Density

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Estimation of corrected stability and flow values
after applying correction factors.
Bitumen
Content
%
Stability (kN) Flow
(0.25mm)
Sample
1
(kN)
Sample
2
(kN)
Average
(kN)
Correction
Factor
Corrected
Stability
(kN)
Sample
1
(mm)
Sample
2
(mm)
Average
(mm)
3.5% 19.96 26.93 23.445 1.38 32.35 5.55 4.57 5.06
4% 28.38 30.52 29.45 1.22 35.93 6.9 12.63 9.765
4.5% 27.12 27.62 27.37 1.24 33.94 4.44 6.34 5.39

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3.0% 3.2% 3.4% 3.6% 3.8% 4.0% 4.2% 4.4% 4.6%
30
31
32
33
34
35
36
37
Stability (kN) vs Bitumen Content
Bitumen Content (%)
Stability
(kN)

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Estimation of percentage of air void:
Formula:
Where,
Gt= Theoretical specific gravity
Gt= Bulk specific gravity
For 3.5% Binder
Sample1:
=42.56%
Sample2:
• =38.01%

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For 4% Binder
Sample1:
=40%
Sample2:
=38.25%
For 4.5% Binder
Sample1:
=38.91%
Sample2:
=37.33%
•

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Estimation percentage of air voids
Bitumen Content
%
Specific gravity
Gt
Bulk specific gravity
Gm
Air voids
Pa (%)
3.5% 2.42 14.64 40.285 %
4% 2.4 1.485 39.125 %
4.5% 2.39 1.455 38.12 %

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Air Voids (%) vs Bitumen Content (%)
3.2% 3.4% 3.6% 3.8% 4.0% 4.2% 4.4% 4.6%
37.00%
37.50%
38.00%
38.50%
39.00%
39.50%
40.00%
40.50%
f(x) = − 2.175 x + 0.4788
Voids Ratio
Voids Ratio Linear (Voids Ratio)
Bitumen Content
Air
Voids
(in
%)

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Theoretical Specific Gravity of mix normal betumen+rubber (Gt):
Formula:
Where,
W1= Weight of course aggregate.
W2= Weight of filler, dust
Wb= Weight of bitumen Specific
G1= Specific Gravity course aggregate =2.6
G2= Specific Gravity of filler =2.4
G3= Specific Gravity of bitumen =1.09
• Gr= Specific Gravity of rubber= 1.38
wR= Weight of rubber

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For 3.5% Binder (Bitumen 90% + Rubber 10%)
W1= 264+276+240 =780 gm
W2= 420 gm
Wb= 37.2 gm
wR= 4.2 gm
=
Gt1= 2.42………Sample1
Gt2= 2.4………Sample2

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For 3.5% Binder (Bitumen 80% + Rubber 20%)
W1= 264+276+240 =780 gm
W2= 420 gm
Wb= 33.6 gm
wR= 8.4 gm
=
Gt1= 2.42………Sample1
• Gt2= 2.42…………Sample2

48. For 3.5% Binder (Bitumen 70% + Rubber 30%)
W1= 264+276+240 =780 gm
W2= 420 gm
Wb= 29.4 gm
wR= 12.6 gm
=
Gt1= 2.31……Sample1
Gt2= 2.31……Sample2
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For 4% Binder (Bitumen 90% + Rubber 10%)
W1= 264+276+240 =780 gm
W2= 420 gm
Wb= 43.2 gm
wR= 4.8 gm
=
Gt1= 2.40………Sample1
• Gt2= 2.40………Sample2

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For 4% Binder (Bitumen 80% + Rubber 20%)
W1= 264+276+240 =780 gm
W2= 420 gm
Wb= 38.4 gm
wR= 9.6 gm
=
Gt1= 2.41…………Sample1
Gt2= 2.41…………Sample2

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For 4% Binder (Bitumen 70% + Rubber 30%)
W1= 264+276+240 =780 gm
W2= 420 gm
Wb= 33.6 gm
wR= 14.4 gm
=
Gt1= 2.41………Sample1
• Gt2= 2.41………Sample2

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For 4.5% Binder (Bitumen 90% + Rubber 10%)
W1= 264+276+240 =780 gm
W2= 420 gm
Wb= 48.6 gm
wR= 5.4 gm
=
Gt1= 1.82…………Sample1
• Gt2= 1.82………Sample2

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For 4.5% Binder (Bitumen 80% + Rubber 20%)
W1= 264+276+240 =780 gm
W2= 420 gm
Wb= 43.2 gm
wR= 10.8 gm
=
Gt1= 2.40……………Sample1
• Gt2= 2.40……………Sample2

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For 4.5% Binder (Bitumen 70% + Rubber 30%)
W1= 264+276+240 =780 gm
W2= 420 gm
Wb= 37.8 gm
wR= 16.2 gm
=
Gt1= 2.40………Sample1
Gt2= 2.40………Sample2

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Rubber+Betumen

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Experimental Studies
1. AIM: To determine the specific gravity and water absorption of aggregate.
2. AIM: To find out the stripping value of the road aggregates.

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Experiment.1
• AIM: To determine the specific gravity and water absorption of aggregate.
• Apparatus:
• A wire basket of not more than 6.3 mm mesh or a perforated container of
convenient size with thin wire hangers for suspending it from the balance.
• A thermostatically controlled oven to maintain temperature of 100°c to 110°c.
• A container for filling water and suspending the basket. An airtight container of
capacity similar to that of the basket.
• A balance of capacity about 5 kg. to weigh accurate to 0.5 g. and of such a type
and shape as to permit weighing of the sample container when suspended in
water.
• A shallow tray and two dry absorbent clothes, each not less than 750 X 450 mm.

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Procedure
• About 2 kg of the aggregate sample is washed thoroughly to remove fines, drained and then placed in
the wire basket and immersed in distilled water at a temperature between 22°c to 32°c with a cover of
at least 50 mm of water above the top of the basket.
• Immediately after immersion the entrapped air is removed from the sample by lifting the basket
containing it 25nn above the base of the tank and allowing it to drop 25 times at the rate of about one
drop per second.
• The basket and the aggregate should remain completely immersed in water for a period of 24 hours
afterwards.
• The basket and the sample are then weighed while suspended in water at a temperature of 22°c to
32°c. in case it is necessary to transfer the basket and the sample to a different tank for weighing, they
should be jolted 25 times as described above in the new tank to remove air before weighing. This
weight is noted while suspended in water w1 gram.
• The basket and the aggregate are then removed from water and allowed to drain for a few minutes,
after which the aggregate are transferred to one of the dry absorbent clothes. The empty basket is than
return to the tank of water, jolted 25 times and weight in water w2 g.

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• The aggregates placed on the absorbent clothes are surface dried till no further
moisture could be removed by this cloth.
• Then the aggregates are transferred to the second dry cloth spread in a single layer,
covered and allowed to dry for at least 10 minutes until the aggregates are
completely surface dry. 10 to 60 minutes drying may be needed.
• The aggregates should not be exposed to the atmosphere, direct sunlight or any
other source of heat while surface drying.
• A gentle current of unheated air may be used during the first ten minutes to
accelerate the drying of aggregate surface.
• The surface dried aggregate is maintained at a temperature of 110 degree Celsius for
24 hours. It is then removed from the oven, cooled in airtight container and weighed
W4 g. At least two tests should be carried out, but not concurrently.

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Calculation
W1 weight of aggregate in air
W1=2002.5 gram
W2 weight of basket in water
W2=1291.5 gram
W3 weight of aggregate plus basket in water
W3= 2509 gram

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W4 dry weight of aggregate
W4=1977.5
WS weight of aggregate
WS=W3-W2
Ws=2509-1291.5
=1217.5 gram
Weight of aggregate

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Specific Gravity:
Formula:
a)
b)

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Water observation=
Formula:
Limits: The specific gravity of aggregate ranges from 2.5 to 3.0
The water observation of aggregate ranges from 0.1 to 2.0
•

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Sieving of Aggregate
Weight of aggregate 2 kg
Aggregate sieved from 10mm and passing return from 4.75mm

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25 times drop in water to clean aggregate Then completely dry aggregate with cloths

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Hite at the temperature

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Experiment.2
• AIM: To find out the stripping value of the road aggregates.
• PRINCIPLE:
• The film stripping device is used to measure resistance of bituminous
mixtures to stripping of the bitumen from the rock particles and is
generally used to evaluate the mineral aggregate.
• However, it may be used to judge the adhesive capacity of the
bituminous material. Stone screenings for use in seal coats or open
graded mixes are usually subjected to this test.
• The test is applied to the aggregate fraction passing 10mm sieve and
retained on 2.36mm sieve. Four specimens can be tested simultaneously.

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Sieving of Aggregate
Sieve 20mm aggregate passing and
12.5mm return aggregate.
Collect 200 grams Aggregate

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Hite at 90 degree temperature Collecting 5% bitumen from total 200gr
aggregate and mix it in aggregate

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Then Putting in water Hite at 24 hours at the 35% temperature

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Result: Removed 20% stripping bitumen from aggregate

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PROCEDURE
• 1) Coat 60g sample of aggregate which passes through 10mm IS Sieves
and retained on 2.36mm IS Sieve with the bitumen to be tested.
• 2) Keep it in the bottle and cure the sample for 15hours at 60°C.
• 3) Allow it to cool to room temperature at 25°C. 4) Add 175ml of distilled
water.
• 5) Similarly take the specimens in the other three bottles and screw on the
caps to the bottles having the rubber gasket in between the bottle top and
the cap. Clamp the bottles to the disc.
• 6) Switch on the unit and agitate the mixture for 15 minutes.
• 7) Estimate the percentage of aggregate stripped by visual observation.

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Result
 The Stripping value of aggregate= 20%

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Thank you