COTM 4192 Chapter 2-2 Bituminous Materials.ppt

Chair, Infrastructure Design & Construction, EIABC
1
COTM 4203: HIGHWAY
ENGINEERING II

2-2: BITUMINOUS BINDING PAVEMENT MATERIALS
• Lecture Organization
• Basic Definitions
• Types of Bituminous Binders
• Asphalt Cement
• Historical Background
• Source
• Refining Process
• Physical Tests and Procedures
• Grading of Asphalt Cement
• Emulsions
• Cutbacks
2

3
• Objective: After completing this lesson the student is
expected to understand:
1. The different definitions of bituminous
materials.
2. The different types of bituminous binders:
source, production and classifications.
3. The basic physical properties, tests and grading
systems.
4. The main uses of the different types of
bituminous materials and their specification
requirements.

2-2: BITUMINOUS BINDING PAVEMENT
MATERIALS
I. Basic Definitions
• In order to understand the contents and avoid confusions on
different literatures let us first define basic terms.
4
No. Terms America’s literatures British literatures
1 Asphalt Is a dark brown to black cementitious
material, in which bitumen is a
predominant constituent, which occur
naturally or obtained from petroleum
refining.
Is a natural or mechanical
mixture of bitumen with solid
mineral matter or aggregate.
2 Bitumen Is a class of black or dark brown
color cementitious substance,
natural or manufactured, composed
of high molecular weight
hydrocarbons. eg. Asphalt, Tar,
Pitch, Asphaltenes, e.t.c
Is a dark brown to black
viscous cementitious material
obtained naturally or produced
from petroleum refining
process.

MATERIALS
No. Terms America’s literatures British literatures
3 Asphalt
Cement
A fluxed or unfluxed asphalt
specially prepared with quality and
consistency for construction of
pavement.
Is a binding material having
cementing qualities suitable
for construction of asphalt
pavement.
4 Asphalt
Concrete
Is a mixture of asphalt binder with
aggregate for the construction of
pavement.
5
As per the above definition, both Asphalt and Bitumen refers to the
same material in America and Britain, respectively.
Therefore, for our case we will use asphalt and bitumen
interchangeably to refer to the basic constituent of the HMA.

II. Bitumen/Asphalt Vs Tar
 Asphalt Cement and Tar are considered as Bituminous
Materials.
 The above two terms, Bitumen and Tar, are always
confusing due to misconceptions resulting from their
similarity in appearance and in some parallel
applications.
 However, there are basic differences in source, physical
as well as chemical properties.
 Bitumen: is a black to dark brown cementing material
obtained naturally or from refining petroleum.
 Currently, it is in use in almost all parts of the world,
exclusively.
6

MATERIALS
 Tar: is a dark cementing material produced by
destructive distillation of bituminous coal.
 It has a distinctive odor and currently, it is
hardly in use due to;
 Its some undesirable physical
characteristics such as, very high
temperature susceptibility.
 Its significant health hazard, such as; eye
and skin irritation due to fume.
7

MATERIALS
Criteria Bitumen Tar
Color Dark brown to black. Dark color.
Source Naturally or Petroleum
Refining.
Destructive distillation of
Bituminous coal.
Odor Have distinctive odor.
Undesirable Physical
Characteristics
High temp. susceptibility
and health hazard.
Application Currently in use. Outdated.
Solubility Soluble in petroleum
products.
Resistant to petroleum
products.
8
Comparison of Bitumen and Tar

III. Types of Bituminous Binding Materials in
Pavement Construction
• The main types of bituminous binding materials
used in pavement construction include:
A. Asphalt Cement/ Bitumen
B. Emulsions
C. Cut backs
9

MATERIALS
10
Cutbacks Emulsions
Bituminous Materials
Natural Bitumen Refinery Bitumen
Lake
asphalt
Rock asphalt
Penetration grade
bitumen
Liquid bitumen
Slow curing
cutback
Medium curing
cutback
Rapid curing
cutback
Anionic
emulsion
Cationic
emulsion

A. Asphalt Cement /Bitumen
I. Historical Background
• Asphalt Cement is one of the man’s oldest engineering materials
due to its adhesive and water proofing properties.
• It was used in ship building industry by Sumerian in 6000 BC.
• In Indus valley ancient civilization, it was used in large public
bath construction before 3000 B.C.
• In 2600 B.C it was used in mummification, water proofing and
building construction by Egyptians.
• In general, in ancient civilizations, it was used as mortar in
building and paving blocks and numerous water proofing
applications.
• Currently, it is used as Main Flexible Pavement Materials since
1876 when it is first used in Asphalt Pavement Construction in
Pennsylvania Avenue, WD.
11

II. Sources of Asphalt Cement
• The two main sources of Asphalt Cement are:
• Natural Asphalt
• Petroleum Asphalt
a. Natural Asphalt
 Naturally exists in two forms:
1. As relatively soft asphalt material [Trinidad, Bermudez,
etc].
2. As hard, friable and black material in the veins of rocks or
impregnated in various stones; lime stone and sand stone.
[Western Canada].
12
Some of the predominant sources of Natural Asphalt includes; Trinidad
Asphalt Lake, Bermudez, Venezuela, etc.

2-2 BITUMINOUS BINDING PAVEMENT
MATERIALS
13
Trinidad Lake Asphalt

MATERIALS
• Trinidad Asphalt Lake was the earliest source of
Asphalt for Pavement Construction in 1876.
• The lake had supplied more than 90% of the world
wide consumption of asphalt from 1875 to 1900.
• The estimated capacity of Trinidad asphalt lake is
about 8,000,000 tones of Asphalt.
14

b. Petroleum Asphalt
 Obtained from fractional distillation of petroleum.
 Became dominant after invention of refining of petroleum
and popularity of Automobiles.
 Currently, available in quantity and quality for any
construction.
III. Petroleum Refining Process
 Crude Oil/ Petroleum: is a mixture of heavy molecular
weight hydrocarbons found naturally buried under the crust
of earth.
 It is found throughout the world; however, the main sources
include, Mexico, Venezuela, Middle East, USA, the former
USSR, Northern and Western Africa, etc.
15

MATERIALS
• Different sources of Crude Oil have different contents due to
the difference in geological formation.
• Accordingly, Crude Oils from different sources have different
Asphalt Content.
• One of the index used to measure the content of asphalt in
Crude Oil is American Petroleum Institute [API] Gravity.
• API Gravity =
16
141.5
Specific
Gravity
_ 131.5

MATERIALS
• API Gravity is an arbitrary expression of density of
materials expressed at 60oF.
• Some typical values include:
17
Substance Typical API Values
Water 10
Asphalt 5-10
Gasoline 55
Low API Gravity Crude Oil < 25 [yields high % Asphalt]
High API Gravity Crude Oil > 25 [yields low % Asphalt ]

18
Boscan
Venezuela
Arabian
Heavy
Nigerian
Light
API Degree
Sp. Gravity
% sulfur
10.1
0.999
6.4
28.2
0.886
2.8
38.1
0.834
0.2

 Basic Refining Process:
• Crude Oil is heated in large furnace to above 340oC
and partially vaporized. The vapor is fed into
distillation tower where lighter components drawn
off for further processing.
• The residue of the above process [asphalt] is fed into
vacuum distillation unit where heavier gas oils are
drawn off.
• The residue of the above process considered as a
straight run Asphalt or can be further processed. 19
Atmospheric
process
Vacuum
process

IV. Physical Tests of Asphalt Cement
 The main physical tests in Asphalt can be
categorized as follow:
22
Asphalt Physical Tests
Consistency
Tests
Durability
Tests
Purity
Tests
Safety Tests Other
Tests
1 Viscosity Test
[Absolute &
Kinematic]
Thin film Oven
Test [TFO]
Solubility
Test
Flash Point
[Cleveland
Open Cup Test]
Specific
Gravity
2 Penetration Spot Test
3 Softening Point
[Ring and Ball
Test]
Rolling Thin Film
Oven Test [RTFO]
4 Ductility Test

• N:B. as part of the Superpave [Superior Performing Asphalt
Pavement] there are new performance evaluating tests. Such
as
i. Pressure Aging Vessel Test – [PAV]
ii. Rotational Viscometer – [RV]
iii.Dynamic Shear Rehometer – [DSR]
iv.Bending Beam Rehometer –[BBR]
v. Direct Tension Tester – [DTT]
• However, this lecture will only focus on the conventional
tests only.
23

I. Consistency Test
• Consistency refers to the degree of fluidity of Asphalt
Cement at any particular temperature
• Since asphalt is thermoplastic material, its consistency
depends on Time, Temperature and Loading.
24
Temp. 25 oC
Time : 1 hrs
Temp. 60 oC
Time : 1 hrs
Temp. 25 oC
Time : 4 hrs

MATERIALS
• As shown earlier, the following empirical tests are used for
measuring consistency:
1. Viscosity [Absolute and Kinematic ]
2. Penetration
3. Softening point
4. Ductility
• Before discussing each test let us look the representative
testing temperatures:
25
Temperature Condition represented
25 oC Average Pavement Temperature
60 oC Maximum Pavement Temperature
135 oC Mixing, Pumping, Spraying, etc Temp.

MATERIALS
1. Absolute Viscosity Test @ 60oC
• Viscosity is defined as a resistance to flow of fluid.
• Two types of viscometers are used:
1. Cannon –Manning Vacuum Viscometer
2. Asphalt Institute Vacuum Viscometer
26

MATERIALS
• The test method and procedure is described on ASTM D2171
• Procedures :
i. The viscometer is mounted in thermostatically controlled constant
water or oil bath at 60oC.
ii. Asphalt will be charged to the viscometer & apply partial vacuum
to assist movement.
iii. Record the time the asphalt take to pass between the time marks.
iv. Calculate the viscosity as:
i. V2 = T2 [V1/T1]
27
Where, V2 = Viscosity of the unknown material
V1 = Viscosity of standard material
T2 = Time of unknown material
T1 = Time of standard material
But [V1/T1] =calibration constant and provided by
manufacturers

2. Kinematic Viscosity @ 135oC
• Test method and procedure is ASTM D2170
• Zeitfuchs Cross Arm Viscometer.
• Since at 135oC, asphalt is fluid no need of vacuum.
28
Absolute
Viscosity
(poise)
=
Kinematic
Viscosity
(stokes)
x
Specific
Gravity

MATERIALS
• Example: An asphalt Cement has a kinematic viscosity of
800 centistokes. Its specific gravity is 1.03. what is the
Absolute Viscosity of the asphalt.
• N:B:
• 1 stoke = 100 centistokes
• The unit of absolute viscosity is poise and kinematic viscosity is
stokes.
29

MATERIALS
3. Penetration Test
• It is the first empirical consistency test invented by, H.C.
Bowen of the Barber Asphalt Paving Company in 1888.
• Conducted at 25 oC to simulate
the average service pavement
temperature.
• The test methods and procedure
is described on ASTM D-5
30

• Test procedure:
1. A container of asphalt brought to a standard temperature
of 25oC in thermostatically controlled bath.
2. The sample is placed under a needle of specified
dimension.
3. The needle is loaded with 100gm weight and allowed to
penetrate for 5 sec .
4. The depth of penetration is measured on 0.1mm [dmm]
as penetration unit.
• N:B: for highly viscous asphalt the penetration is small and
vise versa.
31

MATERIALS
4. Softening Point Test [Ring & Ball Test]
 It is the temperature at which an asphalt cement began phase
change.
 Test method and procedure is ASTM D-36.
32
Procedure:
i. Fill asphalt in the brass rings
and suspend in backer filled
with water.
ii. Place the steel balls on the
asphalt.
iii. Heat the bath at a rate of
5oC/min.
iv. Record the temperature at
which the asphalt touch the
bottom arrangement.
v. Average the results of the 2
samples.

5. Ductility Test
• It is an empirical test that measures the resistance of asphalt
for cracking failure.
• It is the distance in cm that a standard briquette of asphalt will
stretch before breaking.
33
MATERIALS

II. Durability Tests
• Durability is a measure of how well an asphalt binder retains
its original properties when subjected to normal weathering
and aging process.
• Aging is the hardening of asphalt. It is the main problem in the
Asphalt Pavement Performance.
• When Asphalt Cement Ages, its viscosity increases and
become more stiff and brittle.
• The main causes of asphalt aging are:
1. Oxidation: is the reaction of oxygen with asphalt film.
• It increase with temperature and occurs during HMA
production.
• It is the main cause of short term aging.
34

2) Volatilization. The evaporation of the lighter
constituents of asphalt binder.
• It is primarily a function of temperature and occurs
principally during HMA production.
3) Polymerization. The combining of like molecules to
form larger molecules. These larger molecules are
thought to cause a progressive hardening.
4) Thixotropy: It is a reversible rearrangement of asphalt
molecules to cause the asphalt become harder.
• Heating and agitation will reverse this
hardening.
• Pavement with little or no traffic fail due to
thixotrophic hardening.
35

5) Syneresis. The separation of less viscous liquids from
the more viscous asphalt binder molecular network.
6) Separation. The removal of the oily constituents,
resins or asphaltenes from the asphalt binder by
selective absorption of some porous aggregates.
 In addition, aging of asphalt classified into two:
1) Short term aging: which occur during HMA
production.
2) Long term aging: which occur during the life of HMA
pavement due to environmental factors.
36

MATERIALS
• Hence, measuring of Durability relates with measuring of
Aging.
• However, there is no direct test to measure aging. Rather,
standard tests conducted on the aged sample which simulate
the actual condition.
• In order to simulate the short term aging, there are two tests
in the conventional test; these are:
1. Thin Film Oven Test [TFO]
2. Rolling Thin Film Oven Test [RTFO]
37

• Thin Film Oven Test
• Helps to simulate the aging during production of HMA.
• Test method ASTM D-1754.
38
Procedure:
1. Place 50g sample on pan.
2. Place the sample in rotating
shelf of aging machine at 163
oC.
3. The shelf rotate at 5-6 RPM for
5 hrs.
4. Conduct penetration or viscosity
test on the aged sample.
5. Determine the residue
penetration and weight loss

MATERIALS
• Rolling Thin Film Oven Test
• The test method is ASTM D 2876.
• The same function as TFO test but it gives faster result.
39

MATERIALS
III. Purity Test
• Purity test refers to the presence or absence of
insoluble materials in the Asphalt Cement.
• In principle, pure asphalt is entirely soluble in CS2
or Trichloroethylene.
• Test Method used is ASTM D-2042.
• Expressed as a percentage of insoluble with respect
to the total mass of the asphalt.
40

MATERIALS
IV. Safety Test
• During HMA production asphalt heated
at high temperature.
• If the asphalt produce fume it will ignite
and cause fire. Hence, in order to ensure
safety during construction, asphalt
cement should meet safety test
requirements.
• Cleveland Open Cup Test is the main
safety test.
• Test method ASTM D 92.
41

MATERIALS
• Asphalt Cement Grading
• Why we need to grade asphalt????
• Historical development:
• From 1878 to 1900, most of the asphalt used in sheet
asphalt, penetration asphalt and mixed asphalt pavement
were mainly from Trinidad and Bermudez asphalt lakes.
• The asphalt from these sources were profoundly different
in consistency.
• In addition, the grew of petroleum asphalt production
demands the assurance of consistency of asphalt.
42

MATERIALS
• Initially, people uses Chewing to check the softness
[“consistency”] of asphalt.
• In 1888, H.C Bowen of Barber Asphalt Paving
Company, invent the first penetration test and machine.
• In 1910, after several modifications on test machine;
penetration test become principal means of controlling
consistency at 25oC.
• In 1931 American Associations of State Highway and
Transport officials [AASHTO] published standard
specifications for Penetration Grade Asphalt Cement.
43

MATERIALS
• In 1960 the FHWA, ASTM, AASHTO, the industry and state
highway departments wants gradation of asphalt to be done
by Viscosity @ 60oC.
• In 1987, as part of Superpave research programme a new
grading system developed in America called “Performance
Grading” system.
• Hence, in summary of the above developments we do have
three basic asphalt grading system:
1. Penetration Grading
2. Viscosity Grading
3. Performance Grading
44

I. Penetration Grading of Asphalt Cement
• It is based on penetration test on original asphalt @25oC,
100gm weight & 5 sec loading.
• Accordingly, there are five grades of asphalt.
40-50 ; 60 -70 ; 85 -100 ; 120 – 150 and 200 – 300
45
Advantage Disadvantage
1 The test is done at 25° which is
reasonably close to a typical average
pavement temperature.
The test is empirical and does not
measure any fundamental engineering
parameter such as viscosity.
2 Provide a better correlation with low-
temperature asphalt binder properties
than the viscosity test.
3 Temperature susceptibility can be
determined by conducting the test at
temperatures other than 25° C
4 The test is quick and inexpensive.
Therefore, it can easily be used in the
field.
The test does not provide information at
mixing and compaction temperatures.

• Penetration Grade Bitumen is used in road construction, the harder
grades, 35 penetration to 100 penetration, being used in asphalt where
bitumen stiffness is of primary importance and the softer grades, 100 pen to
450 pen, in macadam where the lubricating properties during application
and bonding of the aggregate in service are more important.
46

MATERIALS
II. Viscosity Grading of Asphalt/ Bitumen
 It is based on viscosity test on Original or Aged Asphalt @
60oC.
 There are six grades based on original asphalt and five grades
based on aged asphalt in Rolling Thin Film Oven Test.
 The viscosity grades indicate the viscosity in hundreds of
poises ± 20% measured at 60oC (140oF). For example, AC
2.5 has a viscosity of 250 poises ± 50. AC 40 has a viscosity
of 4000 poises ± 800.
47
Standard Grading based on Original Asphalt (AC)
AASHTO
M 226
AC-2.5 AC-5 AC-10 AC-20 AC-30 AC-40

Standard Grading based on Aged Residue (AR)
AASHTO
M 226
AR-10 AR-20 AR-40 AR-80 AR-160
48
Advantages Disadvantages
1 Unlike penetration test, viscosity
is a fundamental engineering
parameter.
The principal grading (done at 25° C) may not
accurately reflect low-temperature asphalt
binder properties.
2 Temperature susceptibility can
be somewhat determined
because viscosity is measured at
two different temperatures.
When using the AC grading system, thin film
oven test residue viscosities can vary greatly
with the same AC grade. Therefore, although
asphalt binders are of the same AC grade they
may behave differently after construction.
NB: The prefix AC and AR refers to the original and aged asphalt respectively

MATERIALS
49

• Chemical Properties of Asphalt Binders
• It is an asphalt binder’s chemical properties that determine
its physical properties as well as the field performance of
HMA.
• The chemical properties can be studied at:
1. Molecular level
2. Intermolecular level
• The molecular level chemistry of Asphalt is very complex
and less important for our purpose. However, the
intermolecular structure or chemistry determines the
behaviors of Asphalt.
50

51
Asphalt Cement
Asphaltenes Maltenes
Resins Oils
When we dissolve Asphalt
Cement in non-polar solvent
like pentane, hexane, heptanes
1. The precipitate or the
insoluble is known as
Asphaltenes
2. The soluble portions are
known as Maltenes
The main components of Asphalt Cement are:
Asphaltenes:
•are dark brown friable solids
•responsible for the hardening of the
Asphalt cement
Maltenes
•are soluble hydrocarbons
•easily converted into Asphaltenes due to
oxidation or rearrangement.

• Liquid Bitumen
• Liquid binders are modified penetration grade bitumen
prepared as liquid products for handling at relatively low
temperatures and mixed with aggregates either when cold or
warmed slightly.
• The two forms of liquid bitumen's are:
• Bitumen Emulsions: prepared by emulsifying the asphalt
cement in an aqueous medium.
• Cutback Bitumen: prepared by dissolving the asphalt cement
in a suitable volatile solvent to reduce their viscosity to make
them easier to use at ordinary temperatures,
• These types of asphalt are not used in HMA production. However,
they are extensively used in pavement repairs, subgrade
stabilization, bituminous surface treatments (BSTs), slurry seals,
tack coats, prime coats, fog seals, etc. 52

• Asphalt Emulsions
 Produced by breaking asphalt cement, usually of 100-250
penetration range, into minute particles and dispersing them
in water with an emulsifier.
 These minute particles have like electrical charges and
therefore do not unite. They remain in suspension in the
liquid phase as long as the water does not evaporate or the
emulsifier does not break.
 Asphalt emulsions consist of asphalt, which makes up
about 55 percent to 70 percent by weight, up to 30%
emulsifying agent, water and in some cases may contain a
stabilizer.
53

• Two general types of emulsified asphalts are
produced, depending on the type of emulsifier
used:
• Cationic emulsions: in which the asphalt
particles have a positive charge;
• Anionic emulsions: in which they have a
negative charge.
• Each of the categories is further divided into three
subgroups, based on how rapidly the asphalt
emulsion will return to the state of the original
Asphalt Cement as: Rapid Setting (RS), Medium-
Setting (MS), and Slow Setting (SS).
54

• A Cationic Emulsion is identified by placing the letter "C" in
front of the emulsion type; no letter is placed in front of
anionic and non-ionic emulsions.
• For example, CRS-2 denotes a cationic emulsion, and RS-2
denotes either anionic or non-ionic emulsion.
• The anionic and cationic asphalts generally are used in
highway maintenance and construction.
• Since anionic emulsions contain negative charges, they are
more effective in adhering aggregates containing
electropositive charges such as limestone, whereas cationic
emulsions are more effective with electronegative aggregates
such as those containing a high percentage of siliceous
material.
• Cationic emulsions also work better with wet aggregates and
in colder weather.
55

 Bitumen emulsions break when sprayed or
mixed with mineral aggregates in a field
construction process; the water is removed, and
the asphalt remains as a film on the surface of
the aggregates.
 In contrast to cutback bitumen, bitumen
emulsions can be applied to a damp surface.
56

• Cutback Bitumen
• During construction, upon curing by evaporation of the
solvent, the cured-out asphalt cement will be in
approximately the same condition as before being taken
into solution and bind the aggregate particles together.
• The curing period depends on the volatility of solvents.
• Cutback bitumen are grouped into three types based on the
type of solvent, which governs the rates of evaporation and
curing:
 Slow-Curing (SC)
 Medium-Curing (MC)
 Rapid-Curing (RC).
• Each type of cutback bitumen is subdivided into several
grades characterized by their viscosity limits.
• The viscosity is controlled by the quantity of cutback
solvent to make the various grades from very fluid to
almost semi-solid at ambient temperatures.
57

1. Slow-Curing (SC):
• Obtained directly as Slow-Curing Straight-run Asphalts
through the distillation of crude petroleum or as Slow-Curing
Cutback Asphalts by "cutting back" asphalt cement with a
heavy distillate such as diesel oil.
• They have lower viscosities than asphalt cement and are very
slow to harden.
• Slow-curing asphalts are usually designated as SC-70, SC-
250, SC-800, or SC-3000, where the numbers are related to
the approximate kinematic viscosity in centistokes at 60oC
(140oF).
• They are used with dense-graded aggregates and on soil-
aggregate roads in warm climates to avoid dust.
58

• Medium-Curing (MC) Cutbacks:
• Produced by fluxing, or cutting back, the residual asphalt
(usually 120-150 penetration) with light fuel oil or kerosene.
• The term medium refers to the medium volatility of the
kerosene-type dilutent used.
• Medium-curing cutback asphalts harden faster than slow-
curing liquid asphalts, although the consistencies of the
different grades are similar to those of the slow-curing asphalts.
• However, the MC-30 is a unique grade in this series as it is
very fluid and has no counterpart in the SC and RC series.
• The fluidity of medium-curing asphalts depends on the amount
of solvent in the material. MC-3000, for example, may have
only 20 percent of the solvent by volume, whereas MC-70 may
have up to 45 percent.
• These medium-curing asphalts can be used for the construction
of pavement bases, surfaces, and surface treatments. 59

• Rapid-Curing (RC) Cutbacks :
• Produced by blending asphalt cement with a petroleum
distillate that will easily evaporate, thereby facilitating a quick
change from the liquid form at time of application to the
consistency of the original asphalt cement.
• Gasoline or naphtha generally is used as the solvent for this
series of asphalts.
• The grade of rapid-curing asphalt required dictates the amount
of solvent to be added to the residual asphalt cement.
• For example, RC-3000 requires about 15 percent of distillate,
whereas RC-70 requires about 40 percent.
• These grades of asphalt can be used for jobs similar to those
for which the MC series is used, but where there is a need for
immediate cementing action or colder climates.
60

MATERIALS
61
• Currently, the predominant liquid asphalt used
worldwide is Emulsion Asphalt. This is due to:
• Emulsions are Environmentally friendly than
cutbacks.
• Cut backs induce lose of high energy content
products to the atmosphere.
• Emulsions have no fire risk unlike the cut
backs.
• Emulsions can be used in damp conditions and
less energy required.

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