lab report

KAW 3612 – HIGHWAY ENGINEERING

ACKNOWLEDGMENT

First of all, we wish to express our heartiest gratitude and appreciation to our lecturer, Mr.

Ratnasamy Muniandy for his precious time, patience, guidance, motivation and advice on

carrying out all the laboratory tests. Without him, this project would not turn out to be successful

one.

Beside that, we would also like to express our sincere appreciation to the technician, Mr.

Azry Tamber and Mr. Teh Kian Teck, a Master student for providing all the equipment, relevant

suggestion and valuable aids during the process of this project.

Special thanks also to our classmates for their kindness and co-operation, contributions

throughout this study and help us while doing this project to make it successful.

Thank You

1


Physical Properties of asphalt and Aggregate

A Aggregate TestsThe term ‘Aggregate’ refers to granular mineral particles that are widely used for highway

bases, subbases, and backfill. Aggregates are also used in combination with a cementing material

to form concretes for bases, subbases, wearing surfaces, and drainage structures. Sources of

aggregates include natural deposits of sand and gravel, pulverized concrete and asphalt

pavements, crushed stone and blast furnace slag. The Aggregates Test is carrying out to know the

properties of aggregates and the suitable of the aggregates used in highway construction. The

aggregate tests that carry out in this lab are as below:

1.0 Gradation Analysis – HMA Gradation Envelop

1.1 Introduction

Aggregate is the main property of the performance of the pavement layers. The gradation

of aggregate is the blend of particle size of the mix that affects the density, strength and economy

of the pavement structure. There is various size of sieve to design the proportion in a mineral

aggregate mix.

1.2 Objective

Aggregate grading is carried out to determine the proportion of aggregate required from each

stockpile to fit into the given specification.

1.3 Apparatus

Sieves ( 20 mm, 14mm, 10mm, 5mm, 3.35mm, 1.18mm, 0.425mm, 0.15, 0.075mm)

Sieve Shaker

Balance machine

2


1.4 Procedure

1. Approximately 5 kg aggregate from each stockpile are sieved in the specified sieve size.

2. After allocating the aggregate in the sieve, then the mechanical sieve shaker is used to sieve

it.

3. The percent passing the sieve aggregate through the selective size are determined by taking

the weight retained on each individual sieves over the original weight of the aggregate.

4. The passing percent then is plotted on a 0.45 power gradation chart.

5. In highway projects, the material that gain the no.4 sieve is called the coarse aggregate

meanwhile the material that passes the no.4 sieve but retained in the no.200 sieve is known as

the fine aggregate.

1.5 Result

Sieve

size

(mm)

Weight

retain

(g)

Passing

Weight (g)

Percent

retained

(%)

Percent

passing

(%)

Specification

LL (%) UL (%)

20.000 0 0 0 100 100 100

14.000 150 1050 12.5 87.5 80 95

10.000 102 948 8.5 79 68 90

5.000 204 744 17 62 52 72

3.350 102 642 8.5 53.5 45 62

1.180 192 450 16 37.5 30 45

0.425 168 282 14 23.5 17 30

0.150 144 138 12 11.5 7 16

0.075 84 54 4.5 7 4 10

Pan 54 0 7

Total 1200 100

Example Calculations

3


The percent retained and passing on sieve size 14 mm is calculated as below:

Percent retained (%) =

=

= 12.5 %

Percent passing (%) = [Percent passing the sieve size higher than the particular sieve] –

[Percent retained on the particular sieve}

= 100 % – 12.5 %

= 87.5 %

1.6 Discussion

From the result above, we have found that the percentage retained is 12.5 % while the

percentage passing is 87.5 %. Generally, we find that the percentage passing the bigger sieves

such as the 10mm sizes and above are higher while the percentage passing the small sieves is

lower. This gradation of aggregates is very important for the pavement structure because it

affects the density and strength. For the aggregate material that is retained on a No. 4 sieve (for

particles larger than 2 mm) is known as coarse aggregate. Materials that passes the No.4 sieve

but is retained on a No. 200 sieve ( particles larger than 0.075 mm) is known as fine aggregates

while the materials that passes a No. 200 sieve is referred as fines. The grain size analysis data

are usually plotted on an aggregate grading chart to aid engineers to determine a preferred

aggregate gradation and require the gradation of aggregates used for highway projects to

conform to the limits of a specification band. From what we can see from the results, the results

conform to the specification band as set by AASHTO.

1.7 Conclusion

4


In conclusion, we can know that the result conform to the AASHTO specifications and

therefore is suitable for usage in pavement design. The gradation analysis is very important to

analyze the correct gradation mix so that it can provide adequate density and strength for the

usage on the road pavement design.

5


2.0 Los Angeles Abrasion Test

2.1 Introduction

The test is done in accordance with ASTM C131.The Los Angeles test is a measure of

degradation of mineral aggregates of standard grading resulting from a combination of action

including abrasion and grinding in a rotating steel drum containing a specified number of steel

spheres. The number steel charges depend upon he amount and grading of the test sample. As the

drum rotates s self plates picks up the sample and the steel spheres, carrying them until they are

dropped to the opposite site of the drum creating an impact-crushing effect. The content s the roll

within the drum with an abrading and grinding action until the self plate impacts and the cycle is

repeated. After the prescribe number of revolutions, the contents are removed from the drum and

the aggregate portion is sieved to measure the degradation as percent loss.

2.2 Objective

The objective of this test is to ascertain the degradation of aggregates by abrasion and impact.

2.3 Apparatus

Los Angeles abrasion machine

Sieve (19mm, 12.5mm, 1.7mm and pan)

Sieve Shaker

Balance machine

2.4 Procedure

1. The sample is washed and dried and later the weight is obtained.

2. The sample is place in LA Abrasion machine.

3. Eleven steel balls are added in the machine.

4. The drum is rotated for about 500 revolutions at 30-33rpm.

5. After being rotated, the sample is removed from the drum and is sieved on no. 12 sieve. Later

the sample that is retained on the sieve on dried at the temperature of 105 to 110°C.The

weight of the sample is takes after the sample is cooling down.

6


2.5 Result

Aggregate size

(mm)

Weight of sample

(g) before

Weight of sample

(g) after

Loss (g)

19 – 12.5 25003850 1150

12.5 – 9.5 2500

Weight loss = (Weight of sample before abrasion) – (Weight of sample after abrasion)= 5000 – 3850= 1150 g

Percent loss = x 100

= x 100

= 23 %

This result is fulfilling the JKR requirement of 30% and it is suitable to be used for road works.

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2.6 Discussion

From this experiment, the abrasion value for aggregates have been tested and determined.

This value is given by the percent of wearing or percent loss for the aggregates. The abrasion

value is important since it gives the measurement of hardness for aggregates that are going to be

used in highway projects. Furthermore it also used to determine the quality of the aggregates

itself. In order to ensure that the aggregates play its role effectively, the aggregates must possess

sufficient strength to retain load acting by heavy machinery such as roller during construction

project and also to retain traffic loading once the roads is complete. These aggregates should not

crush, degrade and disintegrate when subjected to this loading. Aggregates that lack adequate

toughness and abrasion resistance also may cause construction and performance problems.

Degradation occurring during production can affect the overall gradation and, thus, widen the

gap between properties of the laboratory-designed mix and the field-produced mix. The change

in the L.A. Abrasion value can be brought about by changing the specific surface of the

aggregate sample, i.e., the more equal dimensional or cubical the aggregate sample starts off, the

more abrasion resistant the aggregate will seem. Theoretically, the lower the abrasion value, the

more abrasion resistant for the aggregate is. The soft aggregates will be quickly ground to dust,

whilst the hard aggregates are quite resistant to crushing affects.

The value of percent loss calculated is 23 %.This value represented the abrasion resistant

for the given aggregates sample. There are several steps of precautions that need to be

considering during the test in order to minimize errors and to get more desirable results as stated

below:

1. Make sure that the aggregates sample is washed and dried properly (not interrupted)

2. Make sure that the aggregates are sieve accordingly follow the specification. (change in

size will change the properties of aggregates itself and at the same time effect the

performance)

3. Make sure there is no human error when handling the test (i.e. measure weight) or try to

minimize it by taking several readings.

4. Make sure that the sample is dried under the temperature of 105°C to 110°C after it is

removed from drum. (change in temperature will affect the cooling process and also the

sample weight)

8


2.7 Conclusion

From the test that had been done, we can say here that it had achieved the main objectives

that is to determine the degradation of aggregates by abrasion and impact. The percent loss

calculated is 23% and this value measure the abrasion resistant for the aggregates sample tested.

This value can be acceptable since it lies within the JKR requirements for L.A Abrasion Test that

is below 30%. The value obtained indicated that this sample can sustain or resist the possible

abrasion and impact before or during the service period of road and it is suitable to be used for

road work irrespective of other standard test of aggregates. More precise value can be obtained if

we consider the precaution steps that have been discussed.

9


3.0 PSV and Skid resistance

3.1 Introduction

The Polished Stone Value (BS 812: Part 11V) gives a measure of resistance of road stone

to the polishing action of the pneumatic tire. Under conditions similar to those occurring on the

surface of the road where the surface of the roads consists largely of road stone, the state of

polish of the sample will be one of the major factors affecting the resistance of the surface to

skidding. The actual relationship between Polished-Stone Value and skidding resistance will

vary with the traffic condition, type of surfacing and others factors. All factors, together with the

reproducibility of the test, should be taken into account when drawing up specifications for

roadwork’s, which include test limit for Polished –Stone Value.

3.2 Objective

To measure the extent of aggregates in wearing course that would be polished under the traffic

flow.

3.3 Apparatus

An accelerated polishing machine, which shall be rigidly mounted on a firm, level, and

resilient base of concrete.

Metal moulds for preparation of specimens

Friction test

British Standard Sieve

Material consisting of no.36 corn emery and air-floated emery flour.

3.4 Procedure

1. Specimens are prepared as shown in the standard and the particle use shall pass the 9.52 mm

and be retained on the 7.94 mm British Standard Sieve.

2. Specimens are polished using the polishing machine. Temperature should be within 27

degree Celsius during the polishing period.

3. Water and no.36 corn emery are fed continuously on the road wheel within the period of 3

hours. Then the machine and the specimens are washed to remove the trace of the corn

emery.

10


4. Step 2 is repeated with the air floated emery flour replacing No.36 corn emery but the rate of

feed of water must be twice that of emery flour.

5. The specimens are store facing downwards under water at temperature of 25 degree Celsius

for duration of ½ to 2 hours.

6. Later the specimens are removed from the water and tested on the friction tester.

7. Before the friction is done, the specimens and the rubber slider must be wetted. After doing

this the pendulum is released from its original position and the reading is taken from the

pointer.

3.5 Result

Specimen

No.

PSVMean

1 2 3 4 5

1 52 52 51 51 50 51.2

2 51 51 50 50 50 50.4

3 50 50 50 49 49 49.6

4 52 52 51 51 51 51.4

Mean 50.65

Control

Specimen

No.

PSV

Mean1 2 3 4 5

1 52 52 52 52 52 52

2 52 52 52 51 51 51.6

Mean 51.8

11


Calculation

PSV = S + 52.5 – C

= 50.65 + 52.5 – 51.8

= 51.35

3.6 Discussion

From the test that had been conducted, a value that gives a measure of resistance between

the road stone and the polishing action by tire is determined. This value is usually referred as the

polishing stone value (PSV). One of the most major problems in the road traffic safety is

skidding. The skidding resistance is mainly depends on friction force between tires and the road

surface and the main material that contributed in providing the resistance is the aggregates itself.

Due to this, the main requirement in selecting the aggregates material for road works is that it

can provide a certain level of friction when having contact with the tire to ensure there is no

skidding problem that may lead to an accident. This test can be assumed to represent the actual

interaction between tires and the road surface. In this test, four specimens are made from each

test sample, and are split into pairs and polished on two separate polishing runs. This is done in

order to improve the reproducibility and repeatability of the test. The results are carefully

checked for consistency and are only accepted if set test criteria are met. The higher the test

result, the more polish (or skid) resistant the aggregate is. When the value is too small (<20), it

indicated that the particular aggregate had no resistance to skidding. When designing a road, the

road engineer specifies the minimum PSV value that the aggregate used in the surface course has

to have. This minimum value required depends on the volume and type of traffic using.

The PSV value also depends on the natural types of rocks itself. PSV values of naturally

occurring rocks have been studied on a number of occasions. It has been found as a general rule

that rock types consisting of a variety of mineral grains of different hardness or size, or of harder

grains in a softer cementing matrix, give higher PSV values than rocks composed of uniform

grains of uniform hardness in a similarly hard matrix. The most polish resistant naturally

occurring rock type is grit stone. Flint, a hard siliceous rock, limestone (excepting an occasional

gritty type) and granite tend to have low PSV values and polish too quickly to be used in surface

courses. Basalts and dolerites tend to fall between the low PSV rock types and the grit stones.

12


The value of PSV calculated for the given aggregates sample tested is 51.35. From the

observation, we can listed down here several step of precautions that needs to be consider when

the test is done in order to achieve a desirable results and to minimize errors. The steps are as

below:

1. Make sure that the sample is polish in polishing machine is done under control temperature

of 27°C (increased of temperature lead to the decrease of polishing value due to effect on

rubber resilience used for portable skid resistance)

2. Make sure that the sample is sieve accordingly.

3. Make sure no human error when handling the test (take several readings)

3.7 Conclusion

The test done on the aggregates sample had achieved it main objectives that is to measure

the extent of aggregates in wearing course that would be polished under the traffic flow. The

PSV value for the tested sample is 51.35. This value can be acceptable since it meet the JKR

requirements for PSV Test that is over 40. This value indicated that the aggregates sample tested

is suitable in providing adequate resistance of potential skidding that might occur during the

service period of road and it is suitable to be used for road work irrespective of other standard

test of aggregates. More precise value can be obtained if we consider the precaution steps that

have been discussed.

13


4.0 Specific Gravity Test

4.1 Introduction

The specific gravity is important properties that are required for the design of concrete

and bituminous. The specific gravity of aggregate is the ratio of its mass to that of an equal

volume of distilled water at the specified temperature. This test is carried out to determine the

specific gravity of aggregate from different source and type. It also helps to get the absorption

value.

4.2 Objective

The test is to determine the specific gravity of aggregate.

4.3 Apparatus

A balance to permit the basket containing the sample to be suspended from the beam and

weighed in water.

A well-ventilated oven.

A wire basket or perforated container.

A stout, watertight container in which the basket may be suspended.

Cloth.

A shallow tray

An airtight container

4.4 Procedure

1. The sample of 1 kg aggregate is thoroughly washed, drained and the placed in the wire

basket and immersed in distilled water.

2. Then, the entrapped air is removed from the sample by lifting the basket containing it 25

mm above the base of the tank and allowing it to drop 25 times. The basket and aggregate

remain completely immersed during this operation for a period of 24 hours afterwards.

3. The basket and sample are then jolted again and the weighed in water.

4. The basket and aggregate are removed from the water and emptied from the basket on to

the dry cloths.

14


5. The aggregate placed on the dry cloth shall be gently surface –dried with the cloths. The

aggregate then weighed.

6. The aggregate is then placed in the oven in the shallow tray at a temperature of 105°C ±

5°C and maintained at this temperature for 24 hours.

7. Then it will be removed from the oven, cooled in the airtight container, and weighed.

4.5 Result

Weight of

sample in air

(g)

Weight of

sample in

water (g)

Saturated

weight (g)

Dried

weight

Absorption Specific

gravity

1000 596.6 1005 990 0.5 2.45

Absorption = x 100

= x 100

= 0.5%

Specific gravity =

=

= 2.45%

15


4.6 Discussion

From the test that had been done, the specific gravity for the aggregates sample is

determined. This test also is follow with the absorption test in determine the absorption value for

the sample. Absorption for aggregates is important since it influence the performance of

aggregates due to the drying process. Aggregates with high absorption value will influence the

effectiveness of dry equipment to dry the aggregates before bring into mixing with asphalt.

Difficulties in extracting the water from aggregates will produce mix that easily fails due to the

attack of water. The balance of water left inside the mix will soon cause the aggregates to loose

inter particle bonding and spill out easily. It can be stated here that the greater the water

absorption percentage, the more likely that an aggregates will have from susceptibility problems

in cold climes (rainy day).

Because the aggregates for road pavement usually measure by its weight, then the specific

gravity is the important factor in determining the desirable mix need. Gradation specification

only authentic if the part of course and fine aggregates having the specific gravity nearly the

same. If the specific gravity for the fine part higher than the course part, then it resulted to mix

that having not enough of fine aggregates. In opposite, if the specific gravity for course part is

higher than the fine part, then the mix produced will consists too much of fine aggregates.

The absorption value calculated in terms of percentage for the aggregates sample that had

been tested is 0.5%.Specific gravity for the sample is 2.45%. There are several steps of

precautions that need to be considered when the test is done. If one of these steps is neglected, it

may cause variation when the results obtained. The steps are as below:

1. Make sure that the aggregates sample is wash thoroughly to remove possible existing

impurities material from the aggregates that might effects the performance later.

2. Make sure that the sample is completely immersed in the water for about 24 hour before

weight is taken.

3. Make sure that the sample is gently surface-dried before weight is taken to fulfill fully

saturated surface dry condition.

4. Make sure that the entrapped air is removes completely after immersion. The presence of

air will not allowing the water to absorb through aggregates and effects the weight taken.

16


5. Make sure there is no human error occurs. The error can be reduced by taking several

readings during test and find the average.

4.7 Conclusion

This test achieved its main objective that is to determine the specific gravity of aggregates

from different source and type and also helps to get the absorption value. Specific gravity for

sample tested is 2.45% with absorption of 0.5%. This value is consider small and can be

acceptable. From the results obtained, we conclude that these aggregates are suitable for

roadwork irrespective the other standards of tests required. This is because the low absorption

value for the sample indicate that the aggregates itself provide good resistance of failure due to

the possible attack of water before and during the service of the road. More accurate values can

be obtained if we consider the precautions steps that have been discussed.

17


5.0 Flakiness and Elongation Test

Introduction

The type of rocks and type of crushing machine highly determine the shape and size of the

aggregates produced. Elongated and flaky stones are normally not very suitable for roadwork’s

since the shape and the make them difficult to compact. As such the flakiness and elongation test

mush be carried out to determine the suitability of the material.

5.1 Flakiness Index Test

5.1.1Objective

This test is to determine the suitability of the material.

5.1.2 Apparatus

Sieve (50mm, 37.5mm, 25mm, 20mm and pan)

Sieve Shaker

Balance machine

A metal gauge plate.

5.1.3 Procedures

1. Three samples of aggregates weighing 2.5kg each is prepared: Tte aggregates of the first

sample passing 50mm BS sieve and retained on 37.5 mm BS sieve, those of the second

sample passing 37.5 mm BS sieve and retained on the 20 mm BS sieve.

2. Each sample is gauged in turn of thickness on the metal gauge.

3. Finally, weighed the passing material of each sample.

18


5.1.4 Result

Passing sieve

(mm)

Retained sieve

(mm)

Sample (Nos) Passing (Nos) Flakiness

index (%)

50 37.5 0 0 0

37.5 25 95 11 11.58

25 20 146 12 8.22

Average 6.6 %

Example calculation

The flakiness index of aggregate passing sieve size 37.5mm and retained on sieve size 25mm

was calculated as follows:

Flakiness index (%) =

=

= 11.58%

Average =

=

= 6.6%

19


5.1.5 Discussion

Based on the result obtained, each sample collected has about less than 15% flaky

aggregates. This shows that the samples are quite suitable to be used for bituminous mix. But,

the appropriate percentage of flaky aggregates in each sample is determined by the specification

stated in respective manual used for different purpose. For sample passed 37.5mm and retained

on 25mm sieve has flakiness index 11.58% while sample, which passed 25mm and retained on

sieve 20mm has the flakiness index about 8.22%. This makes the average flakiness index

become 6.6%. Aggregates that flaky could always lower the workability of concrete and also

affects its long-term durability. In bituminous mixtures, flaky aggregates make for a harsh mix

that can crack or break up during the compaction process.

5.1.6 Conclusion

After carried out the test, the flakiness index of the collected sample is determined. By

knowing the average index of about 6.6%, the sample collected is very suitable for bituminous

mix. But, different bituminous mix may require different proportion of flaky aggregates.

Therefore, appropriate manual should be referred in order to gain the right mixture of aggregates

for an accurate bituminous mix.

5.2 Elongation Index Test

5.2.1 Objective

This test is to determine the suitability of the material.

5.2.2 Apparatus

Sieve (50mm, 37.5mm, 25mm, 20mm and pan)

Sieve Shaker

Balance machine

A metal gauge plate.

20


5.2.3 Procedures

1. Three samples of aggregates weighing 2.5kg each is prepared: the aggregates of the first

sample passing 50mm BS sieve and retained on 37.5 mm BS sieve, those of the second

sample passing 37.5 mm BS sieve and retained on the 28 mm BS sieve and the third sample

passing 28mm BS sieve and retained on the 20mm BS sieve.

2. Each sample is gauged in turn of length on the metal gauge.

3. Finally, weighed the retained material of each sample.

5.2.4 Result

Example calculation

The flakiness index of aggregate passing sieve size 37.5mm and retained on sieve size 25mm

was calculated as follows:

Flakiness index (%) = x 100

=

= 1.05%

Average =

=

= 1.72%

5.2.5 Discussion

Passing

sieve (mm)

Retained sieve

(mm)

Sample (Nos) Retained (Nos) Elongation

index (%)

50 37.5 0 0 0

37.5 25 95 1 1.05

25 20 146 6 4.11

Average 1.72%

21


Based on the result obtained, each sample collected has about less than 5% elongated

aggregates. This shows that the samples are quite suitable to be used for bituminous mix. But,

the appropriate percentage of elongated aggregates in each sample is determined by the

specification stated in respective manual used for different purpose. For sample passed 37.5mm

and retained on 25mm sieve has flakiness index 1.05% while sample, which passed 25mm and

retained on sieve 20mm has the flakiness index about 4.11%. This makes the average flakiness

index become 1.72%. Aggregates that elongated could always lower the workability of concrete

and also affects its long-term durability. In bituminous mixtures, flaky aggregates make for a

harsh mix that can crack or break up during the compaction process.

5.2.6 Conclusion

After carried out the test, the elongation index of the collected sample is determined. By

knowing the average index of about 1.72%, the sample collected is very suitable for bituminous

mix. But, different bituminous mix may require different proportion of elongated aggregates.

Therefore, appropriate manual should be referred in order to gain the right mixture of aggregates

for an accurate bituminous mix.

22


6.0 Soundness Test

6.1 Introduction

The soundness of aggregates or their resistance to the forces of weathering is undoubtedly

one of the most important considerations in the selection of a material for highway material

construction. The primary exposure that one is concerned with is alternate freezing and thawing.

Somewhat less frequently one may be concerned with resistance of materials to alternate heating

and cooling, wetting and drying, or the action of aggressive waters.

The common soundness requirement for aggregates is based on a sodium or magnesium

sulfate soundness test.

The method may be used for “acceptance of material but rejection should be based on

other determinations such as freezing and thawing tests”. Freezing and thawing tests of aggregate

are also commonly used as the basis for a soundness specification.

In the particular case of aggregates for Portland cement concrete, soundness in freezing

and thawing is something specified on the basis of results of tests in which concrete, made with

the aggregate, is exposed to alternate freezing and thawing and the deterioration of the concrete

is noted.

Specification based on this type of test appears to be better founded than those based on a

sulfate soundness test. It has been stated by Powers, however, that such test are not capable of

giving reliable information about durability of concrete as most commonly used in the field. He

suggests that a better approach would be measurement of the length of time that the concrete

remains immune to frost attack while it is exposed to moisture.

6.2 Objective

To determine the resistance of aggregates to disintegration by saturated solution of sodium

sulphate.

To measure the resistance of aggregates to cycle of freezing and thawing.

To judge the soundness of aggregates subject to weathering action.

23


6.3 Apparatus

Containers

Balance (accurate to 0.01g)

BS Sieve with square openings

Oven

6.4 Procedures

1. The sample of coarse aggregate is washed thoroughly and dried to constant weight at 105-

110˚C and separated it into the different sizes by sieving to refusal. Weighted out the proper

weights of sample for each fraction are and placed it in separate containers for the test.

2. Then, the samples is immerse in the prepared sodium sulphate solution for approximately 18

hours in such a manner that the solution covered the aggregates to a depth of at least ½ in. The

container is covered to reduce evaporation and prevent the accidental addition of extraneous

substances. Maintained the samples immersed in the solution at a temperature of 21 ± 1˚C for

the immersing period.

3. The aggregate sample from the solution is removed after the immersing period and the

permitted it to drain for 15 ± 5 min, and the sample is placed in the drying oven (105 to

110˚C). The sample at specified temperature is dried until constant weight has been achieved.

During the drying period, the samples is removed from the oven, then the sample is cooled to

room temperature, and weighed at time intervals of not less than 4hr and not more than 15 hr.

Constant weight may be considered to have been achieved when successive weights for any

sample, made as described above, differed by less than 1.0g in the case of coarse aggregate

samples.

4. After constant weight has been achieved, cool the samples to room temperature, when they

shall again be immersed in the prepared solution.

5. The process of alternate immersion is repeat and dried for 5 days.

6. After the completion of the final cycle and after the sample has cooled, the sampled is washed

to let it free from sodium sulphate.

7. When the sodium sulphate has been removed, the sample is dried at 105 to 110˚C. Then,

weighed each fraction of the sample.

8. Weighted average calculated from the percentage of loss for each fraction.

24


6.5 Result

Aggregate size Weight of sample

1g (before)

Weight of sample

1g (after)

Percent loss14

14 999.4 994.0 0.54

10 1000.7 994.4 0.41

5 500.4 498.9 0.3

Percent loss =1.25%

6.6 Discussion

Based on the result obtained, aggregates of size 14 have loss about 0.54% after exposed to

long period of weathering process. For aggregates of size 10 and 5 have loss about 0.41% and

0.3% respectively undergone the same process. Therefore, the total loss of the sample is about

1.25%. Certain aggregates may be unsuitable for a highway construction application because if

the aggregates unable to resist the weathering process happened. This is because an aggregate

that is not durable is unstable physically and chemically. Crack may occur due to freezing and

thawing process. Temperature may also affect its durability. For instance, water accumulated in

the crack of the aggregates may be frozen when the temperature decrease and melted when vice

versa. The freezing and thawing process may lead to disintegration of the aggregates. Aggregates

used for roadway construction subject to plenty of chemical substances in the soil. This chemical

sentences may be acidic or alkalinity. Therefore, aggregates subjected to these chemical

substances can be weathered. This will definitely affect the aggregates durability and strengths of

the aggregates will be reduced. Furthermore, the bonding effect between aggregates and

bituminous materials will affected too. Then, the strength of the pavement will be affected at last.

So, is important to determine the durability of aggregates by soundness test before it is used for

construction.

25


6.7 Conclusion

The durability of aggregates is commonly measured by soundness test, as specified in the

manual. This test measures the resistance of aggregates to disintegration in a saturated solution

of sodium or magnesium sulfate. It stimulates the weathering of aggregates that occur in nature.

From the result obtained, percentage of loss of the sample collected is 1.25%. therefore, the

sample is very durable and suitable for highway construction.

26


7.0 Impact Tests

7.1 Introduction

Impact value of an aggregate is the percentage loss of weight of particles passing 2.36mm

sieve by the application of load by means of 15 blows of standard hammer and drop, under

specified test condition. 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 their resistance

to a slowly applied compressive load.

7.2 Objective

To determine the aggregates impact value in the laboratory.

7.3 Apparatus

Impact testing machine

It consists of a cylindrical hammer of 13.5kg sliding freely between two vertical supports.

Its fall is automatically adjusted to a height of 38 cm. There is a brass plate over which an

open cylindrical steel cup of internal diameter 10.2 cm and 5 cm depth is placed and fixed

to the brass plate.

Measure

A cylinder of internal diameter 7.5 cm and 5 cm deep for measuring aggregate.

Tamping rod of 1 cm diameter and 23 cm long rounded at one end and pointed at the other

end.

Sieve

12.5 mm, 10 mm and 2.36 mm openings.

Balance

5000-g capacity

Laboratory oven capable of maintaining a constant temperature up to 110˚C.

27


7.4 Procedures

1. The aggregate is sieve to obtain the portion passing 12.5 mm and retained on 10 mm sieve.

2. Then, the aggregate obtained is washed and dried at a constant temperature of 105˚ to 110˚C;

and the sample is cooled.

3. The aggregate obtained in the cylindrical measure is filled in layers, tapped each layer 25

times with the tamping rod. Using the straight edge, the surface of tamping rod is leveled.

4. Then the aggregate is weight in the measure. This weight of the aggregate is used for the

duplicate test on the same material.

5. After that, the aggregate is transferred from the cylindrical measure to the cup in three layers

and each layer compacted by tamping in 25 strokes with the tamping rod.

6. The hammer is release to fall freely on the aggregate. The test sample is subjected to a total

of 15 blows.

7. Then, the aggregate sample is removed from the cup and is sieved through 2.36 mm sieve.

8. Finally, the fraction passing the sieve is weighed.

7.5 Result

Sample A B

Weight of cylindrical measure, Wc (kg) 2.9 2.9

Weight of cylindrical measure, Wc + sample (kg) 3.46 3.47

Weight of pan,Wp (kg) 0.85 0.85

Weight of sieve size 2.36mm, Ws (kg) 1.46 1.46

Weight of sieve size 2.36mm, Ws + weight of sample retained (kg) 1.96 1.96

Weight of pan,Wp + weight of sample passed (kg) 0.89 0.88

28


Sample

No.

Aggregate

size (mm)

Weight before

(g)

Weight after

(g)

Weight passing

2.36 mm sieve (g)

A 12.5 - 10 560 500 40

B 12.5 - 10 570 500 30

Average 12.5 - 10 565 500 35

Aggregate impact Value, AIV =

=

= 6.19%

7.6 Discussion

Based on the result obtained, sample A 7.14% of aggregates impact value while sample B

has 5.26% of aggregates impact value. This makes up the average value of 6.19%. Aggregates

impact value is used to determine sustainability of aggregates due to dynamic loading or static

loading. As we know, aggregates is an important material used for road construction, therefore,

traffic loading will be the chief loading for a roadway. Aggregates used for road construction

should be able to sustain heavy lading applied. This parameter is measured by impact test. From

the test carried out, we know that the sample has low impact value. This shows that percentage

of aggregates deformed and crashed into smaller particles is less. Therefore, this aggregates is

very sustainable to heavy loading. Experience has shown that in asphalt road construction, the

quality of the courses (wearing course plus binder course) is primarily dependent on the quality

of the individual construction materials. This is especially true for wearing courses, which are

made using the Stone Mastic Asphalt principle. Here the choice and quality of the aggregate

plays an exceptionally important role.

29


7.7 Conclusion

After carried out impact test, we can conclude hat the sample has an aggregate impact

value of 6.19%. This shows that the aggregates are very sustainable and hard. Therefore, it is

very suitable to use for roadway construction. The aggregates used for road construction should

be hard enough to resist dynamic loading due to heavy traffic. Soft aggregates can easily turn

into smaller particles when subjected to loading. Therefore, the pavement constructed will not be

stiff and strong.

30


B. Asphalt TestsAsphalt have no odor, are more resistant to weathering and less susceptible to

temperature than tar. Asphalt will be dissolved in petroleum oils. A large number of different

laboratory tests are performed on asphalt for the purpose of checking compliance with the

specification that is being used. The Asphalt Tests that carry out in this lab are as below:

1.0 Penetration Test

1.1 Introduction

The penetration test is an empirical test used to measure the consistency of asphalt cement.

Generally, the penetration of a bituminous substance may be defined as distance in hundredths to

which a standard needle penetrates the material under known conditions of time, loading and

temperature.

The various grades of asphalt cement are distinguished by their hardness, as

measured by a field penetration test. For purposes of field identification, the consistency of

asphalt cement maybe approximated at room temperature as hard (penetration 40-85), medium

(penetration 85- 150), and soft (penetration 150-300). These limitations are flexible, as complete

accuracy is not essential. You can make an approximation of the hardness while in the field

by attempting to push a sharpened pencil or nail (in this lab, needle has been used) into the

asphalt at 77°F with a firm pressure of approximately 10 pounds. When the pencil point

penetrates with difficulty or breaks, the asphalt cement is hard. When it penetrates slowly with

little difficulty, the asphalt cement is medium. If the pencil penetrates easily, the asphalt cement

is a high penetration or soft grade.

Theory

Penetration Test is used to determine the grade of asphalt cement. In performing the test,

the needle is carefully brought to contact with the surface of the sample, then released so as to

exert a pressure of 100 grams. The seconds after the needle is released, the distance it penetrated

the sample is read, to the nearest 0.01 centimeter, on the penetrometer dial. The reported

penetration is the average of at least three tests on the same material whose values do not differ

more than four points between maximum and minimum. In addition to grade determination,

the penetration test is useful for other purposes, such as detecting overheating or

31


prolonged heating of asphalts in storage tanks. Also, when the asphalt is extracted from a

pavement, the penetration test is useful in determining how the asphalt has changed with age

and weathering.

Penetration = ( R1 + R2 + R3 ) / 3

Where: R is the penetration reading at different locations

1.2 Objective

To measure the penetration value of asphalt which is melted and cooled and kept at a room

temperature of 25oC (77 °F).

1.3 Apparatus

Penetration Needle

Water bath

Time device

Penetration Container

Penetrometer

Thermometers

1.4 Procedure

1. The asphalt is heated until it is fluid enough to pour. Then asphalt is poured into appropriate

sample container which the container should be large enough such that sample depth is at

least 10 mm greater than maximum needle penetration depth and minimum lateral dimension

of 70 mm.

2. The sample container (100g) is place directly on the submerged stand into the penetrometer.

Then the sample container is keep completely covered with water at temperature of

25o±0.5oC.

3. Needle holder is checked and guided to ensure that needle is cleaned and guided apparatus

was functioning properly. The penetration needle is clean with toluene or other solvent and

dries it with a clean cloth. Then insert the needle carefully in the penetrometer.

4. The needle slowly lowered into the water bath until the tip just makes contact with the

surface of the asphalt sample. Then either note the penetrometer reading or set it to zero.

32


5. Quickly the needle holder is released and allowed the needle to move under its own weight

for a total of 5 seconds, then locked the position of the needle. Get the reading in units of 0.1

mm. (If the sample container moves during the test, that result should be discarded.)

6. Three penetration measurements at points on the surface is make not less than 10 mm from

the side of the container and not less than 10 mm apart.

1.5 Result

Number of penetration Penetration (mm)

1 69

2 73

3 65

Average 69

Penetration =

= 69 mm

33


1.6 Discussion

The penetration of an asphalt substance may be defined as the distance (in hundredths of a

centimeter) to which a standard needle penetrates the material under known conditions of time,

loading and temperature. The standard penetration test procedure involves use of the standard

needle under a load of 100 g for 5 seconds at a temperature of 25 C (or 77 F). This test is

handled for the purpose of testing the consistency of asphaltic material; asphalt exhibits high

surface tension and contain relatively large amount of carbon.

Penetration ranges such as 30-40, 40-50, 50-60, 60-70, 70-85, and 85-100 may be used in

specifying the desired grades of asphalt cements prepared from petroleum. The most common

used asphalt in road constructions in Malaysia is the asphalt with penetration within the range of

85-100.

From the result of penetration obtained, we can say that the penetration rate which

equivalent to 69 mm is acceptable since it fall in the penetration range of 60-70. There is a

precaution step that we need to take into account during handling this test. For example, the

asphalt specimen must be tested using standard needle under a load of 100 g for 5 seconds at a

temperature of 25 C (or 77 F). These precaution step must being practice to ensure the asphalt

prepared is suitable for mix design use.

1.7 Conclusion

The standard penetration test procedure involves use of the standard needle under a load of

100 g for 5 seconds at a temperature of 25 C (or 77F). The penetration of asphalt specimen

obtained from the test is 69 mm, and the result is acceptable.

34


2.0 Softening Point Test

2.1 Introduction

The softening test is defined as the mean of the temperature at which the bitumen disks

often and sag downward a distance of 25 mm under the weight of a steel ball. In other word, it

can be simplified that it is (softening point) the temperature at which bitumen becomes soft

enough to flow. The softening point of asphalt is measured by the "ring-and-ball" test (ASTM

Standard D 2398). The softening point of coal tar pitch is measured by the "cube-in-water" test

(ASTM Standard D 61).

In general, with material of those types, softening does not take place at a definite

temperature. As the temperature rises, those materials gradually and imperceptibly change from

brittle or exceeding slow – flowing materials to softer and less viscous liquid. This method is

useful I determining the consistency of bitumen in establish the uniformity of shipments or

sources of supply.

Theory

This test method covers the determination of the softening point of bitumen in the range

from 30 to 157°C (86 to 315°F) using the ring-and-ball apparatus immersed in distilled water (30

to 80°C), USP glycerin (above 80 to 157°C), or ethylene glycol (30 to 110°C).

Bitumen is warmed until it can no longer support 3.5 grams metal ball - this temperature

is the softening point.

Softening Point =( R1 + R2 ) / 2

Where : R is temperature reading upon the ball touches the bottom plate

35


Softening Point Test Set

ASTM D-36 AASHTO T-53

For determining softening point of asphalt and tar using the ring and ball method

BI-211 Shouldered Ring Assembly Machined brass, height adjustment 1 Set

BI-212 Standard Ball Steel ball, 9.53 mm diameter. 2 Pieces

BI-213 Flash Support Mesh wire gauze variable height adjustment 1 Set

BI-214 Support Assembly Metal, provided with thermometer holder 1 Set

GE-230 Bunsen Burner Heat resources 1 Piece

GE-237 Asbestos Wire Gauze 15 x 15 cm 1 Piece

GE-424 Beaker Glass 1000 ml capacity 1 Piece

GE-646.1 Thermometer ASTM 15 C, 2 to 80oC 1 Piece

2.2 Objective

To determine the temperature at which a phase change occurs in the asphalt cement. It is

measured by ring and ball method in accordance with ASTM D36

2.3 Apparatus

Steel ball, 9.53mm in diameter, weighing between 3.55g

Ring

Ball-centering guide

Ring Holder

Bath

Thermometer

36


2.4 Procedure

1. The hot asphalt is poured into the ring and cooled it to room temperature for about 30

minutes. Then, the sample is leveled.

2. Te ring is placed on the ring shoulder. the temperature in the water bath is maintained at 5 ±

1 o C for 40 minutes and the sample is kept in the water bath at a level of not less than 102

mm and not more than 108 mm from the bottom of the bath.

3. Place the ball in each ball centering guide by using forceps. Then the heat is applied at a rate

of 5 o C per minute and make sure it is increased uniformly.

4. Temperature of each ring and ball is recorded by using thermometer when the specimen

surrounding the ball touches the bottom plate .

2.5 Result

Test 1 2 Average

Softening Point (oC) 45 46 45.5

Softening Point =

= 45.5 oC

37


2.6 Discussion

Since the softening point of asphalt material does not take place at any definite

temperature, but involves a gradual change in consistency with increasing temperature, any

procedure that is adopted for determining the softening point must be arbitrary nature. The

procedure in common use in highway materials laboratories is known as the ‘ring-and-ball

method’ and may be applied to semisolid and solid materials. The ring-and-ball method is also

used to determine the penetration index and in conjunction with penetration and loading time.

The softening point is taken to be the temperature at which asphalt material touches the bottom

of the container.

From the result above, the temperature of the softening point is given as 45.5C. As for

asphalt with penetration of 60-70, the temperature of softening point is in the range of 45 to

52C. Thus, we can conclude that the temperature stated above is within the range; which is

acceptable

.As precaution step, it is important to ensure that the water bath floated with ices is heated

gradually until its temperature increased. Asphalt will become softer as the temperature of water

bath rise, and thus, the temperature of when the asphalt become softer is noted.

2.7 Conclusion

Temperature of the softening point of the tested asphalt specimen is given as 45.5C.

38


3.0 Viscosity Test

3.1 Introduction

Viscosity can simply be defined as resistance to flow of a fluid. Viscosity grading of

asphalt is based on viscosity measurement at 60 o C. This temperature was selected because it

approximates the average pavement surface temperature during hot weather. Viscosity is also

measured at 170 o C where this temperature approximates the mixing temperature.

Brookfield rotational viscometer is used accordance to ASTM D4402 to determine the

viscosity of the asphalt cement at different temperatures. Viscosity can be adjusted by blowing

air through hot bitumen - causing oxidation and an increase in molecular weight - and leading to

more viscous “semi-blown” or “blown” grades.

3.2 Objective

To determine the viscosity of the asphalt cement at different temperature.

3.3 Apparatus

Brookfield rotational Viscometer

3.4 Procedure

1. The 10 ml of preheated asphalt cement is poured into the thermocel and heat the sample to

170oC. Check the temperature by using thermometer.

2. Selected the appropriate spindle and RPM to carry out the test.

3. Reported the result in centipoises.

39


3.5 Result

Shear rate (SR) = 6.8

CP = 1688 at 104○ C

Torque = 15 %

Shear stress (SS) = 134.3

3.6 Discussion

There are two types of viscosity, i.e. kinematics viscosity and absolute viscosity. Absolute

viscosity of asphalt cements, stated in poises, is measured by standard test procedure AASHTO

Designation T202. This test is usually performed at a temperature of 60C (140F). The test

involves the measuring of time required for a fixed volume of the liquid to be drawn through one

of several specially designed capillary tubes by means of a vacuum.

For liquid asphalts, the kinematics viscosity may be measured with a gravity-flow

viscometer (AASHTO Designation T201). As precaution, the time for the fluid to flow between

two points in a capillary tube under carefully controlled conditions of temperature and head is

measured. Using the measured time in seconds and the viscometer calibration constant, then

compute the viscosity of the material in fundamental units, stokes, or centistokes.

3.7 Conclusion

From the viscosity test that has been handled onto asphalt specimen, we found that the

shear rate is 6.8, CP is equivalent to 1688 at 104○ C, asphalt’ torque is 15% and shear stress is

134.3. As for asphalt specimen being prepared, the results obtained are acceptable.

40


4.0 Ductility Test

4.1 Introduction

Ductility is a general meant that the property of the material that permits it to under go for a

greasy deformation without breaking. Ductility may be further defined as a distance in

centimeters to which a standard sample of the material may be elongated without breaking. This

test is applicable only to semisolid asphaltic material that is melted by gentle application of heat.

4.2 Objective

To measure the cementing power of the asphaltic material.

4.3 Apparatus

ductility machine

mold

4.4 Procedure

1. The asphaltic material is melted by a gentle heat and poured into a standard mold.

2. The minimum cross section of the mold is exactly 1 cm 2.

3. The mold then is immersed in the water bath which the temperature is maintained about 77 F.

4. After the sample has attained the desired temperature, the sample is placed in the ductility

machine.

5. The machine is set to the one end held in fixed position while the other end is pulled

horizontally at a standard rate.

6. The behavior of the thread was recorded and the elongation until it starts to break.

7. Then the distance the machine has traveled is recorded which is the ductility of the material.

41


4.5 Result

Ductility = 125 cm

4.6 Discussion

From the experiment, the ductility found is to be 125 cm. Thus it is classified as

ductile because the minimum limit of ductility for the asphalt used should not be less than 100

mm and should be around 125 mm. By getting the results above it also shows the ability of the

material to undergo great deformation (elongation) without breaking. Generally, it also measures

the cementing power of the asphaltic material and therefore the presence of ductility is desirable

in most applications. The binding property is very important because of the pavement road has to

endure hard weather conditions such as heavy rain, acrid condition and strong wind. However,

the value of ductility is not as important as the mere presence or the lack of ductility.

4.7 Conclusion

From the experiment, we can conclude that the sample tested is a very ductile material, thus

it can used to bind the aggregates well in the pavement mix design that is used for the road.

42


5.0 Thin Film Oven Test [Loss on Heating (aging) – use TFO]

5.1 Introduction

Loss of heating is defined as the compound of the material which is volatile evaporate during

the heating process. This volatile compound actually is the main substance that is important

which shows the behavior of the material (asphalt).

5.2 Objective

To determine the effect of heat and air on a film of semi-solid asphalt materials. The effects of

this treatment are determined from measurements of selected asphalt properties before and after

the test.

5.3 Apparatus

Oven

Rotating shelf

Thermometer

container

5.4 Procedure

1. 50 gram of the material is weighted carefully into a standard flat cylindrical container.

2. The cylinder than is placed in a specially constructed oven and the temperature is maintained

at 163C for during 5 hours in the rotating direction.

3. The oven actually is set leveled and rotating in the horizontal plane

4. After being inside for 5 hours the sample then is taken out from the oven, cooled, and

weighted.

5. Then the loss of the sample can be determined, and converted to the percentage of loss of

heating base on the weight of the original sample

43


5.5 Result

Pan 1 Pan 2

Weight of pan (g) 88.2 87.5

Weight of pan + asphalt before heating (g) 146.8 145.0

Weight of pan + asphalt after heating (g) 146.3 144.6

Loss in weight (g) 0.5 0.4

Percent loss (%) 0.85 0.7

Average percent loss 0.78

Example calculation

Pan 1 :

Original weight of asphalt = ( Weight of pan + asphalt before heating) – (Weight of pan)

= 146.8 – 88.2

= 58.6 g

Loss in weight = (Weight of pan + asphalt before heating ) – (Weight of pan

+ asphalt after heating)

= 146.8 – 146.3

= 0.5g

Percentage loss in weight =

= x 100

= 0.85 %

Average Pecentage Loss =

= 0.78 %

5.6 Discussion

44


For the two pans, we have an average percentage weight loss of 0.78 % which is small

by comparison and thus it also shows the percentage of volatile material that is in the asphaltic

material. Indirectly, it also shows the durability of the asphalt against heat and wind. High

percentage of weight loss would also mean that the volatile material could be easily evaporated

and thus reducing the strength in the asphalt. Usually, relatively high temperatures are used in

the plant mixing of asphalt cements and aggregates. However, excessively high temperatures are

detrimental, hardening the mixture and reducing the pavement life. Specifications usually

prescribe the minimum values for the percentage of retained penetrations for the various grades

of asphalt cement.

5.7 Conclusion

The asphaltic material from both of the pans shows that it is durable to the high

temperature condition that may be imposed¤„¸„˜þ§Æ45

¸^„¸`„˜þOJ45QJ45o(45‡h45454545ˆH4545 45§ð

45454545454545454545454545H45454545454545§45ng long pavement life.

45


Marshall Mix Design

1.0 Preparation of specimens for Marshall Analysis

1.1 Introduction

Asphalt mix design is a complex issue with a lot of variables involved. However two

methods of mix design have become popular worldwide. They are the Marshall Mix Design and

the Hveem Mix Design Method. In Malaysia the Marshall Method of mix design has become the

norm in the road industry.

Before any asphalt mixes can be replaced and laid on the road, the aggregate and the binder

types are generally screened for quality and requirement. Approximately 15 samples are required

to be prepared to determine the required Optimum Asphalt Content (OAC). The prepared cahe

samples are to be analyzed for bulk density, air void and stability. By using the Asphalt Institute

Method, the Optimum Asphalt Content are determined from the individual plots of bulk density,

voids in total mix, and stability versus parccant asphalt content. The average of the 3 OAC

values is taken for further sample preparation and analysis.

Another procedure developed in UPM is the inclusion of Resilient Modulus, which is

consider as the important parameter in the performance of pavement. As the previous analysis, a

graph of resilient Modulus versus percentage of asphalt content id to be plotted. From the graph

the percentage of asphalt content is to be plotted. From the graph the percentage of asphalt at the

optimum Resilient Modulus will be determined.

The Optimum Asphalt Content, using UPM’s method, was adopted from asphalt Institute by

averaging the percentage of Asphalt at optimum value for Resilient Modulus, Marshall Stability,

Bulk Density and 4% VTM.

1.2 Objective

To prepare standard specimens of asphaltic concrete for the determination of stability and flow in

the Marshall apparatus and to determine density, percentage air voids and percent of aggregate

voids filled with binder.

46


1.3 Apparatus

mould filter paper Marshall compaction pedestal

1.4 Procedures

1. The aggregate is graded according to the ASTM or BS standard, then the aggregate are over

dried at 170-180oC and a sufficient amount is weighed (about 1200g) for sample preparation

that may give a height of 63.5 mm when compacted in the mould

2. The asphalt is weight and is heated to the a temperature of about 160-165 oC.

3. The aggregate is heated in the oven to a temperature not higher than 28 oC about the binder

temperature.

4. A crater is formed in the aggregates, the binder poured in and mixing carried out until all the

aggregate ate coated. The mixing temperature shall be within the limit set for the binder

temperature. The thoroughly cleaned mould is heated on a hot plate or in an oven to a

temperature between 140 and 170 oC. Te mould is 101.6 mm diameter by 76.2 mm high and

provided with a base plate and extension collar.

5. A piece of filter paper is fitted in the bottom of the mould and the whole mix poured in the

three layers. The mix is then vigorously trowelled 15 times round the perimeter and 10 times

in the centre leaving a slightly rounded surface.

6. The mould is placed on the Marshall Compaction pedestal and gives 50 blows.

7. Te specimen is then carefully removed from the mould, transferred to a smooth flat surface

and allowed to cool to room temperature.

8. Finally, the specimen is measured and weighed in air and water (for volume determination).

If the asphalt mix has an open (porous) texture, the weighing in water will lead to error in

the volume and so the specimen must be coated with a measured mass of paraffin mix. The

specimen is then marked and stored for stability and flow measurement.

47


1.5 Result

% Asphalt

cement

Weight of aggregate (g) Weight of asphalt (g) Total weight (g)

4.0 - 1 1200 50.00 1250.00

4.0 - 2 1200 50.00 1250.00

4.0 - 3 1200 50.00 1250.00

4.5 - 1 1200 56.54 1256.54

4.5 - 2 1200 56.54 1256.54

4.5 - 3 1200 56.54 1256.54

5.0 - 1 1200 63.16 1263.16

5.0 - 2 1200 63.16 1263.16

5.0 - 3 1200 63.16 1263.16

5.5 - 1 1200 69.84 1269.84

5.5 - 2 1200 69.84 1269.84

5.5 - 3 1200 69.84 1269.84

6.0 - 1 1200 76.6 1276.60

6.0 - 2 1200 76.6 1276.60

6.0 - 3 1200 76.6 1276.60

Calculation

Example calculation for the first sample with 4% Asphalt cements content.

(Sample 4 .0 – 1)

% Asphalt Cement =

4.0 % =

Weight of asphalt cement = 50 g

48


1.6 Discussion

In the preparation for the Marshall Mix Design, there are a lot of problems that we have

encountered. The heating oven is a bit spoiled and the temperature inside is not consistent,

therefore leading to long wait for sample to be ready for mixing. The aggregates must be at 180

C while the asphalt must be at 165 C before the mix can be done. Another problem is when

pouring the asphalt into the aggregates on the weighing scale. This is a quite hard to do

procedure because the asphalt is extremely hot and we have to pour exact amount calculated to

get the different mixtures. And if we over pour, we had to get some paper to quickly wipe off

some of the asphalt before the asphalt hardens and the mixture can’t be done. The third problem

is the compacting machines always give us a hard because it doesn’t work properly. We had to

resort to manual compaction by using our hands. The machines will have to be serviced

frequently in order for it to work properly. The jack also has a bit of problem while trying to get

sample out from the mold. Some of the sample has honeycombing because it was not mixed well

enough during the mixing in the hot bowl.

1.7 Conclusion

In conclusion, we didn’t manage to get the sample done within a short period of time

because of all the problems encountered by us such as stated above. However, as we go along,

the procedure becomes a routine and simpler and therefore, we are able to make the sample

much faster than before.

49


2.0 Density and Void Analysis

2.1 Introduction

The specific gravity and absorption of aggregates are important properties that are

required for the design of concrete and bituminous mixes. The specific gravity of a solid is the

ratio of its mass to that an equal volume of distilled water at a specified temperature. Because

aggregates may contain water-permeable voids, two measures of specific gravity of aggregates

are used: apparent specific gravity and bulk specific gravity.

All mix design methods use density and voids to determine basic HMA physical

characteristics. Two different measures of densities are typically taken:

Bulk specific gravity (Gmb).

Theoretical maximum specific gravity (TMD, Gmm).

These densities are then used to calculate the volumetric parameters of the HMA.

Measured void expressions are usually:

Air voids (Va), sometimes expressed as voids in the total mix (VTM)

Voids in the mineral aggregate (VMA)

Voids filled with asphalt (VFA)

Bulk Density

If the specimen has a smooth compact surface, i.e. fairly impermeable, bulk density is simply

determined by weighing in air and water. Then:

Bulk Density,d =Gmb x w

Gmb =[ WD / ( WSSD – WSUB )]

Where, d = bulk density ( g / cm3 )

Gmb = bulk specific gravity of the mix.

w = density of water = 1 g / mm3

WD = mass of specimen in air ( g )

WSUB = mass of specimen in water ( g )

WSSD = saturated surface dry mass ( g )

50

http://hotmix.ce.washington.edu/wsdot_web/Modules/05_mix_design/hma_volume_weight.htm#vfa

http://hotmix.ce.washington.edu/wsdot_web/Modules/05_mix_design/hma_volume_weight.htm#vma

http://hotmix.ce.washington.edu/wsdot_web/Modules/05_mix_design/hma_volume_weight.htm#air_voids

http://hotmix.ce.washington.edu/wsdot_web/Modules/05_mix_design/hma_volume_weight.htm#gmm

http://hotmix.ce.washington.edu/wsdot_web/Modules/05_mix_design/hma_volume_weight.htm#gmb


Void in Total Mix (VTM)

The percentage of air voids in the mix is determined by firstly calculating the maximum

theoretical density TMD (zero voids) and then expressing the difference between it and the

actual bulk density, d as a percentage of total volume.

VTM =[ 1 – ( d / TMD ) ] x 100

TMD =Gmm x w

Gmm ={ 1/ [ (( 1- Pb ) / Gse ) + Pb / Gb ]}

Where, d=bulk density ( g / cm3 )

w = density of water = 1 g / mm3

Gmm = maximum theoretical specific gravity of the mix.

TMD = maximum theoretical density ( g / mm3 )

Pb = asphalt content, % by weight of the mix.

Gse = effective specific gravity of the mix

Gb = specific gravity of asphalt cement

Voids in Mineral Aggregate ( VMA )

The volume of void in mineral aggregate ( VMA ) is an important factor for the asphalt mixture design.

VMA=100 x {[ 1- ( Gmb ( 1- Pb ) / Gsb ]}

Where, Gmb = bulk specific gravity of the mix

Pb = asphalt content, percent by weight of the mix.

Gsb = bulk specific gravity of the aggregate.

51


Voids Filled with Asphalt ( VFA )

VFA =[ ( VMA – VTM ) / VMA ] x 100

NB: These calculations involve the manipulation of small differences, therefore great precision is

needed for accurate results.

Typical Marshall Minimum VMA (from Asphalt Institute, 1979)

Nominal Maximum Particle Size

Minimum VMA

(percent)(mm) (U.S.)63 2.5 inch 1150 2.0 inch 11.5

37.5 1.5 inch 1225.0 1.0 inch 1319.0 0.75 inch 1412.5 0.5 inch 159.5 0.375 inch 164.75 No. 4 sieve 182.36 No. 8 sieve 211.18 No. 16 sieve 23.5

2.2 Objective

The test is to determine the Density and Void for specimens

2.3 Apparatus

A balance to permit the basket containing the sample to be suspended from the beam and

weighed in water.

A well-ventilated oven.

A wire basket or perforated container.

A stout, watertight container in which the basket may be suspended.

Cloth.

A shallow tray

52


An airtight container

2.4 Procedures

1. All 15 specimens are measured and weighed in air and water for volume determination. If

the asphalt mix has an open ( porous ) texture, the weighing in water will lead to error in

the volume and so the specimens must be coated with a measured mass of paraffin wax

2. The bulk density, VTM, VMA and VFA for each specimen is calculated according to the

formulas given above. Then, the optimum asphalt binder content for those specimens are

determined.

3. After completing those mentioned procedures as above, the specimens are marked and

stored for stability measurements.

Selection of Optimum Asphalt Binder Content

The optimum asphalt binder content is finally selected based on the combined results of Marshall

Stability and flow, density analysis and void analysis. Optimum asphalt binder content can be

arrived at in the following procedure (Roberts et al., 1996):

1. The following graphs are plotted: As

o Asphalt binder content vs. density. Density will generally increase with increasing

asphalt content, reach a maximum, and then decrease. Peak density usually occurs at

higher asphalt binder content than peak stability.

o Asphalt binder content vs. Marshall Stability. This should follow one of two trends:

Stability increases with increasing asphalt binder content, reaches a peak, then

decreases.

Stability decreases with increasing asphalt binder content and does not show a peak.

This curve is common for some recycled HMA mixtures.

o Asphalt binder content vs. flow.

o Asphalt binder content vs. air voids. Percent air voids should decrease with

increasing asphalt binder content.

o Asphalt binder content vs. VMA. Percent VMA should decrease with increasing

asphalt binder content, reach a minimum, then increase.

53


o Asphalt binder content vs. VFA. Percent VFA increases with increasing asphalt

binder content.

2. The asphalt binder content that corresponds to the specifications median air void content

(typically this is 4 percent) is determined. This is the optimum asphalt binder content.

3. The properties at this optimum asphalt binder content are determined by referring to the

plots. Each of these values are being compared against specification values and if all are

within specification, then the preceding optimum asphalt binder content is satisfactory.

Otherwise, if any of these properties is outside the specification range the mixture should

be redesigned.

54


2.5 Result

% Asphalt cement

Weight in air (g)

Weight in water (g)

SSD Bulk Density

TMD VTM VMA (%) VFA (%)

4.0 - 1 1219.6 675.6 1.2214 2.234518 2.457406 9.0701 17.5898 48.43574.0 - 2 1194.4 659.6 1.1945 2.232941 2.457406 9.1342 17.64798 48.241964.0 - 3 1192.5 656.9 1.1944 *2.218605 2.457406 9.7176 18.1767 46.53799

Average 2.23373 2.457406 9.3073 17.80483 47.738554.5 - 1 1220.2 676.4 1.2216 2.238078 2.439796 8.2678 17.88843 53.781074.5 - 2 1238.1 692.3 1.2393 2.263437 2.439796 7.2284 16.95804 57.374544.5 - 3 1.1991 2.259853 1.1984 0.6688 17.08953 56.84293

Average 2.253789 2.439796 7.6239 17.312 55.999515.0 - 1 1228.0 677.2 1.2290 2.225444 2.422437 8.132 18.77942 56.697255.0 - 2 1245.5 703.0 1.2459 2.294161 2.422437 5.2953 16.2715 67.456495.0 - 3 1190.7 85.2 1.1913 *1.076485 2.422437 *55.562 *60.71223 *8.48319

Average 2.259803 2.422437 6.71365 17.52546 63.076875.5 - 1 1249.4 699.8 1.2501 2.270398 2.405322 5.6094 17.57487 68.082775.5 - 2 1223.3 689.2 1.2241 2.28697 2.405322 4.9205 16.97325 71.010525.5 - 3 1212.0 688.2 1.2146 2.302432 2.405322 4.2776 16.41191 73.93583

Average 2.2866 2.405322 4.9358 16.98668 71.009716.0 - 1 1235.1 0.7081 1.2355 2.341866 2.388448 1.9503 15.43013 87.360286.0 - 2 1248.3 0.7149 1.2494 2.335454 2.388448 2.2188 15.66168 85.833026.0 - 3 1190.4 0.6813 1.1915 2.333203 2.388448 2.313 15.74297 85.30752

Average 2.336841 2.388448 2.1607 15.61159 86.16694( * - not consider)

55


Calculation

Example calculation for the first sample with 4% Asphalt cements content. (Sample 4 .0 – 1)

Bulk density

Gmb =

=

= 2.234518

Bulk Density , d = Gmb x ρw

= 2.235 x 1g/mm3

= 2.234518

Theoretical Maximum Density

Gmm =

=

= 2.457406

TMD = Gmm x ρw

= 2.457406 x 1g/mm3

= 2.457406

Void in total Mix (VTM)

VTM =

= 9.0701%

Void in Mineral Aggregate (VMA)

56


VMA =

=

= 17.5898%

Void Filled with Asphalt (VFA)

VFA =

=

= 48.4357%

Where,

d = Bulk density (g/cm3)

Gmb = Bulk specific gravity of the mix

ρw = Density of water (1g/mm3)

TMD = Maximum theoretical density (g/mm3)

Pb = Asphalt content, percent by weight if the mix

Gse = Effective specific gravity of the mix

Gb = Specific Gravity of asphalt cement

WD = mass of specimen in air (g)

WSUB = Mass of specimen in water (g)

WSSD = Sutured surface dry mass (g)

Gsb = Bulk specific gravity of the aggregate

57


Graph Bulk density versus percent asphalt

2.22

2.24

2.26

2.28

2.3

2.32

2.34

2.36

0 1 2 3 4 5 6 7

% binder

Bul

k de

nsity

(g/c

m3 )

Graph Air Void (VTM) Versus Percent Asphalt

0

2

4

6

8

10

12

0 1 2 3 4 5 6 7

% binder

VT

M

58


2.6 Discussion

For the results obtained, we plotted two graphs. The first graph is density plotted against

the percentage of binder while the second graph is Void in total Mix (VTM) plotted against

percentage of binder. The first graph is supposed to be shaped like a crest curve. However, based

on our results, we plotted a different graph which is not acceptable. There are a few possibilities

which could have lead to the difference in the graphs. It could be due to the sample may still

contains some voids that has water with it because it not fully dried, thus jeopardizing the results.

Secondly, the weighing scale also may give inaccurate results because it has the buoyant effect

of the water on the weighing scale.

Meanwhile, the graph for the VTM against the percentage of binder is acceptable against

the standard graph produced.

2.7 Conclusion

In the results that we get, we can conclude that the results for the VTM against percentage

of binder is not acceptable due to some the mistakes that have been mentioned and therefore

should be rectified accordingly. Meanwhile the graph for VTM against the percentage of binder

can be accepted based on the standard graph produced in the guide book.

59


3.0 Marshall Stability Test

3.1 Introduction

The most widely used method of asphaltic mix design is the Marshall method developed by

the U.S. Corps of Engineers. Stability and flow, together with density, voids and voids filled with

binder are determined at varying binder contents to determine an optimum for stability,

durability, flexibility and fatigue resistance.

The mechanism of failure in the Marshall test apparatus is complex but it is essentially a type

of unconfined compression test. This being so, it can only have limited correlation with

deformation in a pavement where the material is confined by the tires, the base and the

surrounding surfacing. Wheel tracking tests have shown that resistance to plastic flow increases

with reducing binder content whereas Marshall stability has an optimum, below which stability

decreases. Improvement on the assessment, based on stability, is possible by considering flow

and most agencies set minimum for stability and maximum for flow for various purposes such as

for roads, airports and other facilities.

In addition to binder content, stability and flow being the prime variables in the performance of

an asphalt sample. Type of binder, grading of aggregates, the particle shape, geological nature of

parent rock (most importantly, porosity) and degree of compaction also play an important role in

the performance of the asphalt itself

3.2 Objective

To measure the resistance to plastic flow of cylindrical specimens of an asphaltic paving

mixture loaded on the lateral surface by means of the Marshall Apparatus. The method is

suitable for mixes containing aggregates up to 25mm maximum size.

3.3 Apparatus

Marshall apparatus

Water bath

Thermometer

Cloth

Watch

60


3.4 Procedures

The dimension and specification of the Marshall apparatus are explained in ASTM D1559. The

diameter of the specimen is 101.6mm and the nominal thickness is 63.5mm. Table 3.1, taken

from ASTM d1559, gives a correlation ration for stability of specimens which are not 63.5 thick.

1. Three specimens, prepared according to the standard, are immersed in a water bath for 30 at

60±1.0°C.

2. The testing heads and guide rods are thoroughly cleaned. Guide rods are lubricated and the

head maintained at a temperature between 21.1 and 37.8°C.

3. A specimen is removed from the water bath or oven and placed in the lower jar and the

upper jar placed in position. The complete assembly is then placed in the compression-

testing machine and the flow meter adjusted to zero.

4. The load is applied to the specimen at a constant strain rate of 50.8 mm/min until the

maximum load is reached. The maximum force and flow at that force are read and

recorded. The maximum time that is allowed between removal of the specimens from the

water bath and maximum load is 30 second.

61


3.5 Result

% Asphalt cement

Average diameter of sample

(mm)

Average height of sample (mm)

Height

Correlation

ratio

Stability

(KN)

Corrected

Marshall

Stability

(KN)

Flow (mm)

4.0 - 1 100.93 68.87 0.8786 2.82 2.477652* 0.21

4.0 - 2 100.84 67.55 0.90875 4.79 4.352913 0.34

4.0 - 3 100.23 70.47 0.847438 6.09 5.160894* 0.25

Average 4.352913* 0.27

4.5 - 1 100.90 69.23 0.8714 4.43 3.860302 0.37

4.5 - 2 101.87 69.40 0.868 4.53 3.932040 0.47

4.5 - 3 100.10 69.17 0.8726 2.40 2.09424* 0.47

Average 3.896171 0.44

5.0 - 1 101.17 64.97 0.96325 6.28 6.04921* 3.47

5.0 - 2 101.87 68.93 0.8774 4.69 4.115006 0.53

5.0 - 3 101.6 68.47 0.8866 3.37 2.987842* 0.41

Average 4.115006 1.47

5.5 - 1 101.37 70.00 0.85625 3.56 3.04825* 0.53

5.5 - 2 101.20 67.80 0.9025 6.98 6.29945 0.56

5.5 - 3 101.13 67.13 0.91925 7.32 6.72891 0.50

Average 6.51418 0.53

6.0 - 1 101.2 66.83 0.915688 5.07 4.642536 0.54

6.0 - 2 101.07 67.50 0.903125 4.87 4.398219 0.46

6.0 - 3 101.00 65.03 0.96175 3.50 3.366125* 0.59

Average 4.520377 0.53

( * - not consider)

62


Graph Marshall Stability Versus Percent Asphalt

y = -1.1706x2 + 12.661x - 27.301

0

1

2

3

4

5

6

7

8

0 1 2 3 4 5 6 7

Percent Asphalt (%)

Mar

shal

l Sta

bilit

y (K

N)

% Asphalt

Marshall Stability 5.4

Void in total mix (VTM) 5.6

Average 5.5

* Bulk density is not considered here.

Therefore, the Optimum Asphalt Content for HMA Mix = 5.5%

63


3.6 Discussion

Based on the result obtained, 5.5% asphalt content is the most optimum content required

fro HMA mix. This shows clearly in the graph. But, due to the inconsistency of the reading, one

of the plots in the graph need to be ignored in order to obtain more accurate reading.

Inconsistency of the reading is due to:

1. Error of the machine. Skilled personal is required to monitor the machine.

2. Error occurred during mixing of samples. This is because the content of the asphalt

needed for each sample is very hard to the determined. The excess asphalt is very

difficult to retrieve from the aggregates.

3. Temperature is very hard to control during mixing. This is because the oven is not

functioning well.

4. The compaction process needs to be carried out manually due the compactor fail to

work mechanically.

These are all the errors occurred during the process of preparing the samples. All these errors

may lead to the imperfections of the reading. Therefore, some of the readings recorded are not

consistent. Based on the observation of the mix samples, samples with 4% of asphalt content

have many loose aggregates. This is because the content of asphalt needed as binder is not

sufficient and the situation is vice versa when the asphalt content increased to 6%. Therefore, we

need to determine the optimum asphalt content required in order to produce sample with the

optimum plastic flow.

3.7 Conclusion

After carried out the test, we can conclude that the optimum asphalt content needed is

5.5%. But, this figure will be different if subjected to different condition. Factors affecting this

reading are temperature, percentage of aggregates, particles shape, and percentage of fillers.

Therefore, specification in the manual needs to be referred in order to achieve the required

Marshall stability.

64


Reference

1. Highway Materials (A Guide Book for Beginners), Ratnasamy Muniandy, Radin Umar

Radin Sohadi, Penerbit UPM, 2001.

2. Highway Engineering, Paul H. Wright, 6th edition, John Wiley & Son, Inc. 1996

3. www.highways.gov.sk.ca/docs/reports_manuals/manuals/STP_DOC/stp204-

10.pdf+Marshall+Mix+samples+density+and+void+analysis+test+procedure&hl=en&ie=U

TF-8

65

http://www.highways.gov.sk.ca/docs/reports_manuals/manuals/STP_DOC/stp204-

http://www.highways.gov.sk.ca/docs/reports_manuals/manuals/STP_DOC/stp204-