Lab reports transportation engineering i

TRIBHUVAN UNIVERSITY
KHWOPA COLLEGE OF ENGINEERING
An undertaking of Bhaktapur Municipality
Libali, Bhaktapur
A Report on: Transportation Engineering I
Report no: 1
Title: DETERMINATION OF AGGREGATE IMPACT VALUE
SUBMITTED BY: SUBMITTED TO:
Name: Sushrut Gautam Department of Civil Engineering
Roll no: KCE074BCE089 Khwopa College of Engineering
Group: D2 Libali, Bhaktapur
Date of Submission: 2077/10/29

DETERMINATION OF AGGREGATE IMPACT VALUE
OBJECTIVE
To determine the impact value of aggregates.
To assess their suitability in road construction based on impact value.
REQUIREMENTS
I. AIV impact test machine
II. Weighing Balance
III. Metal tamping rod (10mm in diameter and 230mm long)
IV. Standard Sieves
V. Aggregates
THEORY
The aggregate impact value gives a relative measure of the resistance of an aggregate to sudden
shock or impact, which in some aggregates differs from its resistance to a slow compressive
load. The property of a material to resist impact is known as toughness. Due to movement of
vehicles on the road the aggregate is subjected to impact resulting in their breaking down into
smaller pieces. The aggregate should therefore have sufficient toughness to resist their
disintegration due to impact. This characteristic is measured by impact value test.
AIV is the percentage of fines produced from the aggregate sample after subjecting it to a
standard amount of impact. The amount is produced by a known weight. Classification of
aggregate using AIV test is given below:
< 10% = Exceptionally Strong
10 – 20% = Strong
20 – 30% = Satisfactory for road surfacing
>35% = Weak for road surfacing
AIV =
Weight of portion 2.36mm sieve.(W2)
Total weight of dry sample (W1)
∗ 100%
PROCEDURE
1.The test sample consisted of aggregate which passed 12.5 mm IS Sieve and was retained on
a 10 mm IS Sieve. The aggregate comprising the test sample was dried in an oven and cooled.
2. The measure was filled about one-third full with the aggregate and tamped with 25 strokes
of the rounded end of the tamping rod. Further similar quantity of aggregate was added and a
further tamping of 25 strokes given. The measure was finally filled to overflowing, tamped 25
times and the surplus aggregate struck off, using the tamping rod as a straight edge. The net
weight of aggregate in the measure was determined to the nearest gram (Weight A).
3. The impact machine rest without wedging or packing upon the level plate, block or floor, so
that it was rigid and the hammer guide columns were vertical.
4. The cup was fixed firmly in position on the base of the machine and the whole of the test
sample placed in it and compacted by a single tamping of 25 strokes of the tamping rod.
5. The hammer was raised until its lower face was 380 mm above the upper surface of the
aggregate in the cup, and allowed to fall freely on to the aggregate. The test sample was
subjected to a total of 15 such blows each being delivered at an interval of not less than one
second.

6. The crushed aggregate was then removed from the cup and the whole of it sieved on the 2.36
mm IS Sieve until no further significant amount passed in one minute. The fraction passing the
sieve was weighed to an accuracy of 0.1 g (Weight. B).
7. The fraction retained on the sieve was weighed (Weight C) and, if the total weight (C+B)
was less than the initial weight (Weight A) by more than one gram, the result was discarded
and afresh test made.
Fig: AIV Impact test machine
OBSERVATIONS AND RESULTS
Sample 1 Sample 2 Sample 3
Total weight of dry
sample (W1gm) 360 330 325
Weight passing 2.36mm
sieve. (W2 gm) 102 94 88
Aggregate impact value
(%)
28.33 28.48 27.08
Aggregate Impact mean value = 27.96%
SAMPLE CALCULATION
For Sample 1
W1 = 360 gm
W2 = 102 gm
AIV =
𝑊2
𝑊1
∗ 100%
=
102
360
∗ 100% = 28.33%

CONCLUSION AND DISCUSSION
In this way, AIV test can be done in lab using Impact test machine. The percentage of the
aggregate impact value for three sample that we test are 28.33%, 28.48% and 27.08%.
Therefore, the average percentage of the AIV test is 27.96%.
The aggregate impact value is a measure of resistance to sudden impact or shock. AIV is
conducted in the highway engineering laboratory to get the value of aggregate impact.
Aggregate Impact value is used to classify the stones in respect of their toughness property as
indicated below:
Aggregate Impact Value Classification
< 10% Exceptionally Strong
10 – 20% Strong
20 – 30% Satisfactory for road surfacing
>35% Weak for road surfacing
IRC has recommended the following values for different types of road construction:
S.N. Type of Pavement
Maximum aggregate
impact value %
1
Bituminous surface dressing penetration macadam,
bituminous carpet concrete and cement concrete
wearing course.
30
2 Bitumen bound macadam, base course 35
3 WBM base course with bitumen surfacing 40
4 Cement concrete base course 45
Thus, from these tables for our aggregate with AIV 27.96%, it is satisfactory for road surfacing.
According to IRC, given aggregate sample can be used for Bituminous surface dressing
penetration macadam, bituminous carpet concrete and cement concrete wearing course
pavement layer. Errors may arise during the experimentations due to the following reasons:
i. The tamping of aggregate not being uniform and hammering action during tamping.
ii. The volume of aggregate not being uniform in each test.
We have well conducted the experiment on the aggregate for Aggregate Impact Value test. The
main advantage of AIV test is that test equipment and test procedure are quite simple and it
determines the resistance to impact of stones simulating field conditions. The test can be
performed in short time. Well-shaped cubical stones provide higher resistance to impact than
flaky and elongated stones. The less, the Aggregate impact value, the more is its strength and
is better.
PRECAUTIONS
1. The plunger should be placed centrally so that it falls directly on the aggregate sample.
2. The tamping should be done properly by gently dropping the tamping rod and not by
hammering action.
3. Sieving should be done properly and weight of aggregate passing through 2.36mm sieve
after impact should be noted down.
4. Experiment should be performed carefully and safely.
5. Procedure should be followed as instructed.

Libali, Bhaktapur
Report no: 2
Title: DETERMINATION OF LOS ANGELES ABRASION
VALUE OF AGGREGATE

DETERMINATION OF LOS ANGELES VALUE OF AGGREGATE
OBJECTIVE
To determine Los Angeles Abrasion value
To test the hardness property of aggregate.
REQUIREMENTS
I. Los Angeles testing machine
III. Abrasive Charges (48mm diameter and weight of 390 to 445 grams)
IV. Standard Sieves
V. Collecting Tray
VI. Aggregates
THEORY
Los Angeles Abrasion test is widely a common test for abrasion resistance for multiple
engineering applications. The property of aggregate by virtue of which it resists the wearing
effects. The aggregate used in surface course of the highway pavements are subjected to
wearing due to movement of traffic. Due to movement of vehicles on the road the aggregate is
subjected to wearing resulting in their breaking down into smaller pieces. The aggregate should
therefore have sufficient abrasion value to resist their disintegration due to wearing effect. This
characteristic is measured by Los Angeles test in laboratory.
The principle of Los Angeles abrasion test is to find the percentage wear due to relative
rubbing action between the aggregate and steel balls used as abrasive charge. The percentage
wear of the aggregates due to rubbing with steel balls is determined and is known as Los
Angeles Abrasion Value.
The difference between the original weight and the final weight of the test sample is expressed
as a percentage of the original weight of the test sample. This value is reported as the percentage
of wear.
Aggregate Abrasion Value =
𝐴−𝐵
𝐴
∗ 100
Where,
A = weight in gm of oven-dried sample.
B = weight in gm of fraction retained on 1.70 mm IS Sieves after washing and oven-drying
PROCEDURE
A. Gradation of Aggregate
1. Gradation of the Aggregate was carried out so as to assess the Grade of the Aggregate
Sieve size Weight in gm. of Test Sample for Grade
Passing
(mm)
Retained
(mm)
A B C D E F G
80 63 2500
63 50 2500
50 40 5000 5000
40 25 1250 5000 5000
25 20 1250 5000
20 12.5 1250 2500
12.5 10 1250 2500
10 6.3 2500
6.3 4.75 2500
4.75 2.36 5000
Table 1: Gradation of Aggregate

B. Procedure for Los Angeles Abrasion Test
1. The test sample consisted of clean aggregate which was dried to substantially constant
weight and conformed to one of the gradings shown in Table 1. The grading or gradings used
was those most nearly representing the aggregate furnished for the work. (W1)
2. The test sample and the abrasive charge was placed in the Los Angeles abrasion testing
machine and the machine was rotated at a speed of 20 to 33 rev/min. For gradings A, B, C and
D, the machine was rotated for 500 revolutions; for gradings E, F and G, it should be rotated
for 1000 revolutions as mentioned in Table 2.
Grading Number of spheres Weight of charge (gm)
A 12 5000 ± 25
B 11 4584 ± 25
C 8 3330 ± 20
D 6 2500 ± 15
E 12 5000 ± 25
F 12 5000 ± 25
G 12 5000 ± 25
Table 2: Number of Charges as per Grading of Aggregate
3. The machine was so driven and so counter-balanced as to maintain a substantially uniform
peripheral speed.
4. At the completion of the test, the material was discharged from the machine and a
preliminary separation of the sample made on a sieve coarser than the l.70 mm IS Sieve.
5. The material coarser than the 1.70 mm IS Sieve was washed dried in an oven to a
substantially constant weight, and accurately weighed to the nearest gram (W2).
Fig: Los Angeles Abrasion testing machine

Grading selected: B Sample
Weight of oven-dried sample (W1gm) 5000
Weight of fraction retained on 1.70 mm IS
Sieves (W2gm)
3024
Abrasion Value (%) 39.52
Los Angeles Abrasion Value = 39.52%
CALCULATION
W1 = 5000gm
W2 = 3024gm
Aggregate Abrasion Value =
𝑊1−𝑊2
𝑊1
∗ 100
=
5000 − 3024
5000
∗ 100 %
= 39.52%
In this way Abrasion test can be done in lab using Los Angeles Abrasion testing machine. The
Abrasion value was obtained to be 39.52%.
Los Angeles abrasion test is commonly used to evaluate the hardness of the aggregates. The
test has more acceptability because the resistance to abrasion and impact is determined
simultaneously. Depending upon the numerical value, the suitability of aggregates for different
road constructions can be judged as per IRC specifications given below:
S.N. Type of pavement layer
Max. permissible abrasion
value in %
1 Water Bound Macadam, sub base course 60
2 WBM base course with bituminous surfacing 50
3 Bituminous Bound Macadam 50
4 WBM surfacing course 40
5 Bituminous penetration Macadam 40
6
Bituminous surface dressing, cement concrete
surface course
35
7 Bituminous concrete surface course 30
As per specification of IRC, the given aggregate sample with LA abrasion value of 39.52% can
be used for WBM surfacing course and Bituminous penetration Macadam pavement layer.
The given aggregate sample was first graded as per Table 1. We selected Grade B aggregate,
i.e., 2500gm of aggregate passing through 20mm sieve and retained by 12.5mm sieve and
2500gm of aggregate passing through 12.5mm sieve and retained by 10mm sieve, thus making
a total weight of aggregate as 5000gm. For Grade B aggregates, 11 numbers of Abrasive
charges i.e., steel balls were taken as per Table 2. Errors may arise during the experimentations
due to the following reasons:
i. Loss of aggregates due to cover not being tight during rotation.
ii. Number of revolution counts required not being maintained.
Los Angeles abrasion test is very commonly used and accepted test to evaluate the quality of
aggregates for use in pavement construction, especially to decide the hardness of stones.

In this test resistance to both abrasion and impact of aggregate can be obtained simultaneously,
due to the presence of Abrasive charges. Also, the test condition is considered more
representative of field conditions. The less, the value of Abrasion, the better is the aggregate to
resistance against wearing and impact.
PRECAUTIONS
1. The cover should be fixed tightly before rotating the machine.
2. All material should be discharged from the cylinder after the test.
3. The number of revolution count should be maintained as mentioned.

Libali, Bhaktapur
Report no: 3
Title: DETERMINATION OF SOFTENING POINT OF THE BITUMEN

DETERMINATION OF SOFTENING POINT OF BITUMEN
OBJECTIVE
To determine the softening point of bitumen or tar.
REQUIREMENTS
I. Standard Ring and Ball Apparatus
II. Steel balls (2 numbers each of 9.5mm diameter and 3.5 ± 0.05kg)
III. Brass Rings (2 numbers each of depth 6.4mm with inside diameter 15.9mm and
17.5mm at bottom and top respectively)
IV. Thermometer
V. Water bath and stirrer
VI. Bitumen
THEORY
Softening point is the temperature at which the substance attains a particular degree of
softening under specified conditions of test. The softening point is useful in the classification
of bitumen. It is the temperature at which a standard ball pass through a sample of bitumen in
a mould and falls through a height of 2.5cm when heated under water or glycerin at specified
conditions of test. The binder should have sufficient fluidity before its application in road uses.
The determination of softening point helps to know the temperature up to which a bituminous
binder should be heated for various road use application. Softening point is determined by ring
and ball apparatus.
Softening point indicates the temperature at which binders possess the same viscosity.
Bituminous materials do not have a definite melting point. Softening point has particular
significance for materials that are to be used as joint and crack fillers. Higher softening point,
lesser the temperature susceptibility. Bitumen with higher softening point may be preferred in
warmer places. The determination of softening point helps to know the temperature up to which
a bituminous binder should be heated for various road use applications. Softening point is
determined by ring and ball apparatus.
PROCEDURE
1. The material was heated to a temperature between 75 to 100°C above its softening point. It
was stirred until completely fluid and free from air bubbles and water.
2.The rings were placed previously heated to a temperature approximately to that of molten
material on a metal plate, which had been coated with a mixture of equal parts of glycerin and
dextrin.
2. The mould was filled with sufficient melt to give excess above the level of the ring. The
excess material was removed.
3. The apparatus with the rings was assembled with thermometer and ball guides in position.
4. The bath was filled to a height of 50mm above the upper surface of the rings with the freshly
boiled distilled water at a temperature of 5°C.
5. Heat was applied to the bath and liquid was stirred so that the temperature raised at a uniform
rate of 5 + 0.5 °C per minute until the material softened and allowed the balls to pass through
the ring.
6. The temperature was recorded when any of the steel ball with bituminous coating touched
the bottom plate.

Fig: Softening point test of Bitumen
Sample 1 Sample 2
Temperature when the ball touches
bottom, °C
59.9 °C 60 °C
Average 59.95 °C
Softening point of bitumen/tar = 59.95 °C
In this way, it can be concluded that softening point of bitumen can be found in lab using Ring
and bell apparatus. From the data above, the average softening point of bitumen was found to
be 59.95°C.
Softening point indicates the temperature at which bitumen possess the same viscosity. The
softening point is reported as the mean of the temperatures at which the two disks soften
enough to allow each ball, enveloped in bitumen, to fall and touch the bottom of apparatus.
So, softening point is temperature at which a bitumen sample can no longer support the
weight of a 3.5g steel ball. Hard grade bitumen has a high degree of softness temperature
compared with soft bitumen grade. Bitumen with higher softening point do not flow during
service and is preferred in warmer places. As the temperature rises, the bitumen will change
from solid to liquid state which cause the reduction in hardness. While doing the experiment,
some safety measures have to be followed since the bitumen used is hot. Errors may arise
during the experimentation due to the following reasons:
i. The bath temperature not being in range of 5 ± 2°C.
ii. Surrounding temperature not being in range of 27 ± 2°C.
In general, the higher the softening point, the lesser the temperature susceptibility. Softening
point has particular significance for materials that are to be used as joint and crack fillers.
PRECAUTIONS
1. The bulb of the thermometer should be at about the same level as the rings.
2. Distilled water should be used as the heating medium for accurate readings.
3. Equipment used in testing should be cleaned thoroughly.

Libali, Bhaktapur
Report no: 4
Title: DETERMINATION OF PENETRATION VALUE OF BITUMEN

DETERMINATION OF PENETRATION VALUE OF BITUMEN
OBJECTIVE
To determine the consistency of bituminous material.
To determine the penetration value of Bitumen.
REQUIREMENTS
I. Sample container (Cylindrical metallic dish 55mm in diameter and 35mm depth)
II. Penetrometer
III. Penetration needle
IV. Water bath and Stopwatch
V. Thermometer
VI. Transfer tray
VII. Bitumen
THEORY
Penetration of a bituminous material is the distance in tenths of millimeter that standard needles
will penetrate vertically into a sample understand conditions of temperature, load and time.
Penetration is a measurement of hardness or consistency of bituminous material. It is the
vertical distance traversed or penetrated by the point of a standard needle under specific
condition, load, time and temperature. The distance is measured in one tenth of a millimeter.
This test is used for evaluating consistency of bituminous materials.
Penetration test is a commonly adopted test on bitumen to grade the material in terms of its
hardness. An 80/100 grade bitumen indicates that its penetration value penetration value lies
between 80 to 100. The grading of bitumen helps to assess its suitability for use in different
climatic conditions and types of construction. In warmer regions lower penetration grades like
30/40 are preferred to avoid softening whereas higher penetration grade like 180/200 are used
in colder regions, so that excessive brittleness does not occur. Highest penetration grade is used
in spray application works.
Penetration value = G2 – G1
Where, G1 is Initial reading
G2 is Final reading after penetration
PROCEDURE
1. The bitumen was softened to pouring consistency, stirred well and poured into test
containers. The depth of bitumen was kept at 15mm more than the expected penetration in
container.
2. The sample container was placed in water bath at a temperature of 25 °C for about 1 hour.
3. After sometime, the sample was taken out from the water bath and brought in contact the
needle with surface of bitumen sample.
4. The reading of dial gauge were set at zero when the needle was in contact with the surface
of sample.
5. The needle was released and was allowed to penetrate for 5 seconds and the final reading
was noted.
6. Six measurements were taken and the mean value of these six tests was reported as a
penetration value.

Fig: Standard Penetrometer Fig: Penetration value test of Bitumen
Test no
Penetrometer dial reading Penetration value
(div)
Penetration Value
(mm)
Initial Final
1 0 112 112 11.2
2 0 110 110 11.0
3 0 100 100 10.0
4 0 76 76 7.6
5 0 69 69 6.9
6 0 64 64 6.4
Mean Penetration Value 88.5 8.85
In this way, it can be concluded that penetration value of bitumen can be determined easily in
lab using standard penetrometer. The mean penetration value of given bitumen sample was
found to be 88.5, so the grade of bitumen is 80/100.
Penetration test is a commonly adopted test on bitumen to grade the material in terms of its
hardness. Grading of bitumen helps to assess its suitability in different climatic conditions and
types of construction. An 80/100 grade bitumen indicates that its penetration value lies between
80 and 100. The grading of bitumen helps to assess its suitability for use in different climatic
conditions and types of construction. For bituminous macadam and penetration macadam IRC
suggests bitumen grade 30/40, 60/70 and 80/100. In warmer regions lower penetration grades
are preferred to avoid softening whereas higher penetration grades like 180/200 are used in
colder regions so that excessive brittleness doesn’t occur. Highest penetration grade is used in
spray application works.
Based on the result obtained, it was found that the penetration value is not uniform. Due to
decrease in temperature while performing the experiment in cold environment, bitumen

gradually became hard over time, so the penetration values were obtained to be in decreasing
order. It is necessary to maintain uniform temperature while performing Penetration test. The
grade of given bitumen sample observed is 80/100, which is standard grade bitumen usually
used for road construction and for the production of asphalt pavements with superior properties.
Errors may arise during the experimentation due to the following reasons:
i. Surrounding temperature not being in range of 27 ± 2°C.
ii. Sample not being free from impurities and dust.
iii. Oscillation of needle and not cleaning of needle before penetration.
While performing experiment, the needle should just touch the surface of bitumen in mould to
obtain the accurate result. The obtained 80/100 grade bitumen is mainly used in the
manufacture of hot mix asphalt for bases and wearing courses.
PRECAUTIONS
1. The sample should be free from dust and other impurities.
2. There should be no oscillation happening while needle penetrates the bitumen.
3. The needle should be cleaned and dried before each penetration.

Libali, Bhaktapur
Report no: 5
Title: DETERMINATION OF DUCTILITY OF BITUMEN

DETERMINATION OF DUCTILITY OF BITUMEN
OBJECTIVE
To measure the ductility of a given sample of bitumen.
To determine the suitability of bitumen for its use in road construction.
REQUIREMENTS
I. Standard Briquette
II. Pulling device with distance measuring dial.
III. Thermometer
IV. Water bath and Stirrer
V. Bitumen
THEORY
The ductility test gives a measure of adhesive property of bitumen and its ability to stretch. In
flexible pavement design, it is necessary that binder should form a thin ductile film around the
aggregates so that physical interlocking of aggregates is improved. The ductility test of bitumen
is one of the main tests you need to do when building the road. We know that the ductility of a
material is the ability of that material to undergo plastic deformation (permanent deformation)
before the rupture of that material. Binder material having insufficient ductility gets cracked
when subjected to repeated traffic loads and it provides pervious pavement surface.
Ductility of a bituminous material is measured by the distance in centimeters to which it will
elongate before breaking when two ends of standard briquette specimen of the material are
pulled apart at a specified speed at a specified temperature. The binder material which does not
possess sufficient ductility would crack and thus provide previous pavement surface. This in
turn results in damaging effect to the pavement structure.
PROCEDURE
1. The material was heated to a temperature between 75 to 100°C above its softening point till
it became fluid.
2. The mould on a brass plate and coated on all the sides within a mixture glycerin and dextrin
of equal parts to avoid sticking of the material was assembled.
3. The mould was filled until its level is full. The material was poured in a tin stream back and
forth from end to end of mould while filling.
4. The filling was left to cool for 30 minutes and was placed in water bath at specified
temperature for 30 minutes.
5. The excess bitumen was cut off and brass plate and mould was placed with Briquette
specimen, in the water bath and was kept at specified temperature for 80 to 95 minutes.
6. The briquette was removed from the plate, detach sidepieces and was tested.
7. The rings were attached at each end of the clips to the hooks in the testing machine and the
two clips were pulled apart horizontally at a uniform speed of 50mm per minute until the
briquette ruptured.
8. The distance in centimeters through which the clips have been pulled to produce rupture was
measured.

Fig: Ductility test of Bitumen
OBSERVATION AND RESULTS
Briquette no.
1 2 3
Initial Reading (A) 0 0 0
Final Reading (B) 16.6 46.2 49
Ductility = B – A (cm) 16.6 46.2 49
Ductility value =
46.2+49
2
= 47.6cm
In this way, Ductility test of Bitumen can be done in lab using Standard Briquette and Pulling
device with distance measuring dial. The average ductility value of given Bitumen sample was
obtained to be 47.6cm.
The suitability of Bitumen is judged depending upon its type and proposed use. Bitumen with
low ductility value may get cracked especially in cold weather. ISI has specified following
values of minimum ductility for various grades of Bitumen as follows:
Source of paving bitumen and penetration grade
Minimum Ductility value
(cm)
Assam Petroleum
A25 5
A35 10
A45 12
A65, A90 and A200 15
Bitumen from sources other than Assam Petroleum S 35 50
S35, S65 and S90 75
From table, for ductility value of 47.6mm the Source of paving bitumen and penetration grade
is A65, A90 or A200. For bituminous construction, generally ductility value of 50 to 75cm is
taken. The ductility test of bitumen is one of the main tests done during Road construction. It
gives a measure of adhesive property of bitumen and its ability to stretch. In flexible pavement
design, it is necessary that binder should form a thin ductile film around the aggregates so that
physical interlocking of aggregates is improved. The Ductility value is expressed in cm.
We obtained the Ductility value of 47.6cm on average of 2 test data of 46.2cm and 49cm.
The first data of 16.6cm was rejected as it was not in the range of ± 5% of the average value
of three readings.
Errors may arise during the experimentation due to the following reasons:
i. Variation in test and pouring temperature

ii. Sudden pulling of Bitumen during setting up the experiment.
iii. Improper level of briquette placement.
The test was conducted at 27±0.5°C and at a rate of pull of 50±2.5mm per minute as
standardized by the BIS. A certain minimum ductility value is considered essential for a
bitumen binder for satisfactory pavement performance. This is because of the temperature
changes in the bituminous mixes and the repeated deformations that occur in flexible
pavements due to the traffic loads if the bitumen has low ductility value, the bituminous
pavement may crack, especially in cold weather.
PRECAUTIONS
1. No air bubbles shall be formed while filling the mould.
2. The pulling should be done at uniform rate.

Libali, Bhaktapur
Report no: 6
Title: BITUMEN EXTRACTION TEST

BITUMEN EXTRACTION TEST
OBJECTIVE
To determine the percentage of bitumen present in Asphaltic pavement.
REQUIREMENTS
I. Centrifuge apparatus
III. Beaker
IV. Oven or drier
V. Benzene
VI. Bituminous mix
THEORY
Bitumen extraction test is conducted to determine the percentage of bitumen present in an
asphaltic pavement. This test is used to check whether the prescribed amount of bitumen is
used in the mix. The centrifuge extractor is used for the quantitative determination of bitumen
in hot mixed paving mixtures and pavement samples as a field test to exercise quality control
and ensure that the specified amount of bitumen has been used. The bitumen content is
calculated by difference of weight of the extract aggregate, moisture content and ash from the
weight of the sample taken for the test.
The centrifuge extractor is used for the quantitative determination of bitumen in hot-mixed
paving mixtures and pavement samples, essentially as a field test to exercise quality control
and ensure that the specified amount of bitumen has been used. This test is important because
various pavement properties such as durability, compatibility, resistance to various defects and
failure such as raveling, rutting, bleeding etc. depend upon the content of bitumen present as
the binder for the aggregates. Hence, at the site it is necessary to check whether the bitumen
content is as per the mix design or not.
Percentage of binder content =
𝑊1−𝑊2
𝑊2
∗ 100%
Where,
W1 = Weight of sample mix of bituminous material
W2 = Weight of aggregate after extraction of bitumen
PROCEDURE
1. 500g sample of asphalt mix was weighed and was broke with fork into small pieces and was
heat to about 115 °C.
2. The broken sample was placed in bowl and was weighed. The sample in bowl was covered
with benzene and was allowed to soak for one hour.
3. A filter paper was weighed and was placed around the edge of the bowl and a lid on bowl
was clamped.
4. A beaker was placed under the outlet. The bowl was placed in centrifuge and was rotated
gradually to increase the speed up to 3600rpm.
5. The centrifuge was stopped and 200ml of benzene was added and was rotated again.
6. The procedure was repeated not less than three washings until the extract was no longer
cloudy and was fairly light in color.
7. The filter was removed from the bowl and was dried in air. The loose particles were brushed
from the filter into the bowl.

8. The filter was dried to constant weight in oven at about 100°C. The contents of bowl were
dried on steam bath and then to constant weight in oven at about 100°C.
9.The weight of filler and bowl with dry aggregates was obtained.
Fig: Centrifuge Extractor
S.N. Observation Sample
1 Weight of sample mix (W1 gm) 50
2 Weight of aggregate after extraction (W2 gm) 49.4
3 Percentage of binder content (%) 1.21
CALCULATION
W1 = 50gm
W2 = 49.4gm
Percentage of binder content =
𝑊1 − 𝑊2
𝑊2
∗ 100%
=
50 − 49.4
49.4
∗ 100%
= 1.21%
In this way, Bitumen extraction test can be performed in laboratory to determine the percentage
of binder content for Asphalt mix using Centrifuge extractor. The percentage of bitumen
content in given sample was obtained to be 1.21%.
In the given bituminous mix, 1.21% of bitumen to the total mix is present as binder. By
performing this field test a substantial saving in the cost of bitumen can be obtained by ensuring
that the optimum quantity of bitumen has been provided. The results of this test are an

indication regarding the quantity of bitumen that has been used in a bituminous mix. The
performance of the road is affected if lesser or more quantity of bitumen is used, so Bitumen
extractor test helps to ensure the quality of an Asphaltic mix. Errors may arise during the
experimentation due to the following reasons:
i. The bituminous mix not being completely soaked by benzene.
ii. Not maintaining the speed of centrifugal extractor machine.
iii. Leakage due to cover plate not being tight on the bowl.
Benzene is a solvent which dissolves the bitumen. So, we use benzene in bitumen extraction
test to separate bitumen from aggregates, so that separate weights of aggregate can be taken to
find the percentage of bitumen as binder. The centrifugal extractor extracts the bitumen
solution from bowl due to centrifugal action after rotating action is done.
PRECAUTIONS
1. Special care should be taken as extraction may result in emission of fume.
2. The cover plate should be fixed tightly on the bowl.
3. All material should be discharged from the cylinder after the test.

Libali, Bhaktapur
Report no: 7
Title: MARSHALL METHOD OF ASPHALT-CONCRETE MIX DESIGN

MARSHALL METHOD OF ASPHALT-CONCRETE MIX DESIGN
OBJECTIVE
To design the Asphalt concrete mix using Marshall method.
REQUIREMENTS
I. Cylindrical mould
II. Hammer of 4.54kg
III. Breking Head
IV. Sample extractor
V. Dial gauge to measure deformation
VI. Proving ring to measure load
VII. Flow meter, Water bath
VIII. Thermometer
THEORY
Bituminous mixes are used in the surface layer of road and airfield pavements. The mix is
composed usually of aggregate and asphalt cements. Some types of bituminous mixes are also
used in base coarse. The design of asphalt paving mix, as with the design of other engineering
materials is largely a matter of selecting and proportioning constituent materials to obtain the
desired properties in the finished pavement structure.
Marshall method is used in designing and evaluation bituminous paving mixes. The major
features of Marshall method of designing mixes are to determine the two important properties
i.e., strength and flexibility. Strength is measured in terms of ‘Marshall’s stability’ of the mix
which is defined as the maximum load carried by a compacted specimen at weakest condition
for a bituminous pavement in use. The flexibility is measured in terms of ‘flow value’. In this
method, the resistance to plastic deformation of a compacted specimen of bituminous mixture
is measured when the specimen is loaded diametrically at a deformation rate of 50mm per
minute.
PROCEDURE
A. Preparation of sample
1. The coarse aggregates, fine aggregates and the filler material were proportioned and mixed
in a such way that final gradation of the mixture was within the range specified for the type of
bituminous mix. S
2. Approximately 1200 gm. of the mixed aggregates and the filler were taken and heated to a
temperature of 175 to 190 ̊C. The bitumen was heated to a temperature of 121 to 145 ̊C.
4. The required quantity of the first trial percentage of bitumen (say, 3.5 or 4.0 percent by
weight of aggregates) was added to the heated aggregates.
5. It was thoroughly mixed at the desired temperature of 154 to 160 ̊C. The mix was placed in
a pre‐heated mould and compacted by a rammer (4.54kg) with 75 blows on either side at
temperature of 138to 149 ̊C.
7. Three specimens were prepared using each trial bitumen content. The compacted specimens
were cooled to room temperature in the mould and then removed from the molds using a
specimen extractor.
9. The diameter and mean height of the specimen were measured. The weight of each specimen
in air and suspended in water was determined.

11.The specimens were kept immersed in water in a thermostatically controlled water bath at
60 ± 10 ̊C for 30 to 40 minutes.
B. Procedure for Marshal stability test:
1.After placing in water bath, the specimens were taken out one by one. The specimen was
placed in the Marshall Test head.
2.It was then tested to determine Marshall Stability Value which was the maximum load before
failure and the Flow value which was the deformation of the specimen up to the maximum
load.
3.The corrected Marshall Stability value of each specimen was determined by multiplying the
proving ring reading with its constant.
4.If the average thickness of the specimen was not exactly 63.5 mm, a suitable
correction factor was applied.
5.The above procedure was repeated on specimens prepared with other values of bitumen
contents in suitable increments; say 0.5%, up to about 7.5 or 8.0%.
Fig: Marshall Mix design
OBSERVATIONS
CALCULATION
RESULT

PRECAUTIONS
1. Machine shall be properly checked before testing.
3. Readings shall be taken accurately.

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