Pavement Materials
Dr. S. RavirajProfessor of Civil Engineering
JSS Science and Technology UniversitySri Jayachamarajendra College of Engineering
Mysuru - 570 006
e-mail : [email protected]
31st August, 2017
• Soil
• Aggregates
• Bitumen
• Cement
• Recycled Materials
• Geosynthetics
• Etc …
Pavement Materials
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e
Why Testing of Pavement Materials ?
• To ensure quality during construction
• Conforms with appropriate standards.
• To understand the behavior of the
materials individually and in
combination with other materials
Why Testing of Pavement Materials ?
Characterization of materials – Purpose
To classify / Grade
To obtain necessary inputs for design of
new pavement
To ensure proper quality during
construction
To obtain inputs regarding the condition
of materials in an existing pavement
Aggregates
• Major component – road construction.
• Aggregates have to bear stresses
occurring due to the wheel loads on the
pavement.
• On the surface course aggregates also
have to resist wear due to abrasive action
of traffic.
Aggregates are used in
• Pavement construction in Cement concrete,
Bituminous concrete and other Bituminous
constructions
• Granular base course underlying the
superior pavement layers
Hence, properties of the aggregates are of
considerable significance to the highway
engineers.
Types of Aggregates
• Natural aggregates
Obtained from rock
• Artificial aggregates
Slag (metallurgical
process)
Origin of Aggregates• Gravel aggregates are small rounded stones of
different sizes which are generally obtained as
such from some river beds.
• Aggregates are obtained from weathering or
crushing of rocks.
• The properties of the coarse aggregates
depend on the properties of parent rock.
• The properties of the rock depends on the
constituent materials and the nature of bond
between them.
Igneous rocks
• Cooling of molten magma
• Predominantly crystalline
Volcanic rocks (Extrusive)Fine grained minerals
Plutonic rocks (Intrusive)Coarse grained minerals
Igneous rocks
Classification based on grain size
– Coarse ( > 2mm)
– Medium (2mm to 0.2mm)
– Fine ( < 0.2mm)
Igneous rocksClassification based on composition
• Acid rocks ( > 66% silica, light in colour &
specific gravity < 2.75)
• Intermediate rocks (55 to 66% silica)
• Basic rocks ( < 55% silica, dark in colour &
specific gravity > 2.75)
Igneous rocks• Granite
• Basalt (Trap)
Hard and durable
Resistant to abrasion
Low absorption of water
Fine grained to coarse grained texture
Very good for bituminous courses and cementconcrete pavements
Sedimentary rocks• Formed either from the deposition of
– insoluble granular material resulting from
the disintegration of pre-existing rocks, or
– inorganic remains of marine and animals
deposited in great quantities on the sea
floor.
• Sedimentary rocks are deposited in layers,
they have stratified or laminated structure.
Sedimentary rocksClassification based on predominatingmineral:
• Calcareous rock (Chalk, Lime stone & Dolomite)
• Siliceous rock (Sand stone, Flint & Chert)
• Argillaceous (Clay & Shale)
Sedimentary rocks• Limestone
• Sandstone
Reasonably hard and durable
Liable to a smooth polish
Fine grained
High absorption of water
Metamorphic rock• These are sedimentary or igneous rocks that
have been subjected to great heat or great
pressure or both, which has resulted in the
formation of minerals and in textures
different from those of the original rock.
Metamorphic rock• Quartzite
Reasonably hard and durable
Resistant to abrasion
Low absorption of water
Fine grained to medium grained texture
Good for base courses, bituminous courses and cement concrete pavements
Metamorphic rock
Classification based on grain size:
• Fine grain size
–Hornfels & Schist
• Coarse grain size
–Gneiss & Granulite
Classification of Aggregates
• Based on strength property
– Hard aggregates
– Soft aggregates
• Classification based on shape, texture
and gradation
Requirements of Aggregates
• They must be crushed aggregates.
• They shall be clean, hard, durable and cubical
in shape.
• They must be free from the dust, organic
matter and other deleterious matter.
• They must not be flaky or elongated.
Requirements of Aggregates
• They must not consist of harmful materials
since they reduce the strength of pavements.
• They should resist wear due to abrasive action
of traffic on the surface course.
StrengthAggregates - Sufficiently strong to withstand
the stresses due to traffic wheel loads.
Aggregates used in top layer of the pavements,
particularly in wearing course have to be
capable of withstanding high stresses in
addition to wear and tear.
• Crushing strength test
Hardness• The aggregates used in the surface course
are subjected to constant rubbing or
abrasion due to moving traffic.
• They should be hard enough to resist the
wear due to abrasive action of traffic.
Hardness• Abrasive action may be increased due to the
presence of abrasive material like sand
between the tyres of moving vehicles and
the aggregates exposed at the top surface.
• This action may be severe in the case of steel
tyred vehicles.
Hardness• Heavy wheel loads can also cause
deformations on some types of pavement
resulting in relative movement of aggregates
and rubbing of aggregates (attrition) with
each other within the pavement layer.
• However attrition will be negligible or absent
in most of the pavement layers.
Abrasion – Continuous wear and tear under the wheels of vehicles
Attrition – Rubbed with each other due to application of traffic load
Hardness tests – Los Angeles abrasion test
Deval abrasion test
Polished stone test
Hardness
Toughness• Aggregates in the pavements are also
subjected to impact due to moving wheel
loads.
• Severe impact like hammering is quite
common when heavily loaded steel tyred
vehicles move on water bound macadam
roads where stones protrude out especially
after the monsoons.
Toughness• Jumping of the steel tyred wheels from one
stone to another at different levels causes
severe impact on the stones.
• The magnitude of impact would increase
with the roughness of the road surface, the
speed of the vehicle and other vehicular
characteristics.
Aggregates - ability to sustain impact loading
Impact test
Durability• The stone used in the pavement construction
should be durable and should resist
disintegration due to the action of weather.
• The property of the stones to withstand the
adverse action of weather may be called
soundness.
• Soundness Test
Shape of Aggregates• The size of the aggregates is first qualified by
the size of square sieve opening through
which an aggregate may pass.
• Based on the shape of the aggregate particle,
stones may be classified as rounded, angular,
flaky and elongated.
• Aggregates in a particular size range may have
rounded, cubical, angular, flaky or elongated
shape of particles.
Shape of Aggregates• It is evident that the flaky and elongated
particles will have less strength and
durability when compared with cubical,
angular or rounded particles of the same
stone.
• Hence too flaky and too elongated
aggregates should be avoided as far as
possible.
Shape of Aggregates• The voids present in a compacted mix of
coarse aggregates depend on the shape
factors.
• Highly angular, flaky and elongated
aggregates have more voids in comparison
with rounded aggregates.
Shape of Aggregates• Angular particles possess well-defined edges
formed at the intersection of roughly plane
faces and are commonly found in aggregates
prepared by crushing of rocks.
• Flaky aggregates have lesser thickness when
compared to the length and width.
• Elongated aggregates have one of the
dimensions or the length higher than the
width and thickness.
Shape of Aggregates• The shape of aggregates depends on the
source, properties of the rock and the type
and condition of the crushers.
• The shape of aggregates is generally
described in terms of its shape factors such
as flakiness index, elongation index and
angularity number.
Shape of Aggregates• Several researchers have indicated that in
pavement construction flaky and elongated
aggregates are to be avoided, particularly in
surface course.
• If flaky and elongated aggregates are present
in appreciable proportions, the strength of
the pavement layer would be adversely
affected due to possibility of breaking down
during compaction and under loads.
Shape of Aggregates• Several researchers have indicated that in
pavement construction flaky and elongated
aggregates are to be avoided, particularly in
surface course.
• If flaky and elongated aggregates are present
in appreciable proportions, the strength of
the pavement layer would be adversely
affected due to possibility of breaking down
during compaction and under loads.
• Desirable shape
– Angular or rounded
Shape tests – flakiness index, elongation index, angularity number
Shape of Aggregates
Adhesion with Bitumen• The aggregates used in bituminous
pavements should have less affinity with
water when compared with bituminous
material; otherwise the bituminous coating
on the aggregates will be stripped off in
presence of water.
• Stripping test
Tests on Road Aggregates
Type of Test Property Evaluated
Aggregate Impact Test Toughness or resistance to impact
Los Angeles Abrasion Test Hardness or resistance to abrasion
Aggregate Crushing Test Strength or resistance to crushing
Soundness/Durability/ Accelerated weathering test
Durability or resistance to weathering
Shape test: Flakiness Index, Elongation Index and Angularity Number
To measure the quality or strength of material
Specific gravity Test To measure the quality or strength of material
Water absorption Test To measure the porosity
Codes of PracticeProperty Code
Particle size distributionPlasticity Index
IS 2386 – part – 1 IS 2720 – part – 5
Water absorption & Bulk SG IS 2386 – part – 3
Flakiness and Elongation IS 2386 – part – 1
Mechanical PropertiesImpact, Abrasion, Crushing
IS 2386 – part – 4
Soundness IS 2386 – part – 5
Presence of deleterious materials
IS 2386 – part – 2IS 2720 – part – 3
Bitumen coating & Stripping
IS 6241
Water sensitivity test AASHTO T 283
Aggregate Impact Value
Apparatus
• IS sieves (12.5, 10.0 and 2.36 mm)
• Cylindrical measure
• Cylindrical cup
• Weighing balance
• Tamping rod
Aggregate Impact Value
• Weight of aggregates taken = W1
• Weight of aggregates retained on 2.36 mm
sieve = W2
• Weight of aggregates passing through 2.36
mm sieve = W3
• Difference of W1 – (W2 + W3)
• Aggregate Impact Value = W2/W1 x 100
Aggregate Impact Value• < 10 % Exceptionally strong
• 10-20 % Strong
• 20-30 % Satisfactory for road surfacing
• > 35 % Weak for road surfacing
• AIV should not normally exceed 30% for
aggregate to be used in wearing course of
pavements.
• The maximum permissible value is 35% for
bituminous macadam and 40% for water
bound macadam base courses.
Aggregate Crushing Value
Apparatus
• Steel cylinder with open ends and a square plate
• Plunger with piston
• Cylindrical measure
• Weighing balance
• IS sieves
12.5, 10 & 2.36 mm
• Steel Tamping Rod
• Compression testing machine
• Weight of aggregates taken = W1
• Weight of aggregates retained on 2.36 mm
sieve = W2
• Aggregate Crushing Value = W2/W1 x 100
Aggregate Crushing Value
• IRC and BIS specify that the ACV for cement
concrete pavement should not exceed 30
percent.
• For aggregates used for concrete other than
for wearing surfaces, the ACV shall not
exceed 45 percent.
Aggregate Crushing Value
Los Angeles Abrasion TestApparatus
• Los Angles Abrasion M/c
• Steel balls - 11no.
• Weighing balance
• IS Sieves:
20, 12.5, 10 & 1.7mm
Los Angeles Abrasion Test
• Take 2.5 kg of given aggregates in sieve size
20 - 12.5mm
• Take 2.5 kg of given aggregates in sieve size
12.5 - 10 mm
• Total weight of aggregates W1 = 2.5+2.5 = 5kg
Los Angeles Abrasion Test
• Rotate the drum for 100 revolutions
• Wt. of aggregates retained on sieve 1.7 mm = W2
• Los Angles Abrasion value= (W1-W2)/W1 x 100 %
Los Angeles Abrasion Test
• The Los Angeles abrasion value of good
aggregates acceptable for cement concrete,
bituminous concrete and other high quality
pavement materials should be less than 30%.
• Values up to 50% are allowed in base courses
like water bound and bituminous macadam.
Shape Tests
• Flat Aggregates – Flakiness Index
• Elongted Aggregates – Elongation Index
• Equi-dimensional Aggregates – Angularity Number
Flakiness IndexApparatus
• Thickness gauge
• Weighing balance
• IS Sieves of sizes
63, 50, 40, 31.5, 25, 20, 16, 12.5,10 and 6.3 mm
• Flakiness Index of aggregate is the percentage byweight of particles whose least dimension [thickness]is less than three- fifths [0.6] times of their mean size
• The test is not applicable to aggregates smaller than6.3 mm
Flakiness Index
• A minimum of 200 pieces of first fraction to be
tested are taken and weighed = W1 g
• The flaky aggregates passing through the
respective openings are collected and weighed
= w1 g
Flakiness Index
• The procedure is repeated for other fractions
having weights W2, W3, etc. and the flaky
aggregates in them having weights w2, w3
respectively are weighed.
(w1+w2+w3+------)Flakiness Index = ---------------------------- x 100
(W1+W2+W3+------)
Elongation IndexApparatus
• Length gauge
• Weighing balance
• IS Sieves of sizes
63, 50, 40, 31.5, 25, 20, 16, 12.5, 10 and 6.3 mm
• Elongation Index of aggregate is the percentageby weight of particles whose greatestdimension [length] is more than nine - fifths[1.8] times of their mean size
• The test is not applicable to aggregates smallerthan 6.3 mm
Elongation Index
• A minimum of 200 pieces of first fraction to be
tested are taken and weighed = W1 g
• The elongated aggregates not passing through
the respective openings are collected and
weighed = w1 g
Elongation Index
• The procedure is repeated for other fractions
having weights W2, W3, etc. and the elongated
aggregates in them having weights w2, w3
respectively are weighed.
(w1+w2+w3+------)Elongation Index = ---------------------------- x 100
(W1+W2+W3+------)
Angularity Number
• The angularity number of an aggregate is the
amount by which the percentage voids exceeds
33, after being compacted in a prescribed
manner.
• The angularity number is found from the
expression (67 - 100 * W / C * G) %
Angularity Number
Apparatus
• A metal cylinder closed at one end having 3
litre capacity (diameter and height
approximately equal)
• A metal tamping rod, 16 mm in diameter and
600 mm long.
• Weighing balance
• IS sieves 25, 20, 16,12.5, 10, 6.3 and 4.75 mm
Angularity NumberProcedure • The sieves for each fraction (as specified) are
arranged such as 25 - 20 mm, etc.
• The given sample of aggregate is sieved so that
sufficient pieces are obtained in each fraction.
• The empty cylinder is accurately weighed = ‘ a’
• Each aggregate fraction is separately filled in the
cylinder in 3 (three) layers tamping each layer 100
(hundred) times with the rounded end of tamping
rod. The excess aggregate are removed.
Angularity NumberProcedure
• The cylinder along with aggregate is weighed =
‘b’
• The aggregate are removed from the cylinder.
The cylinder is completely filled with water and
after wiping its outer sides it is weighed with
water = ‘c’
• Angularity number = 67 - 100 W / C * G
• W= Wt. of aggregate, C = Wt. of water and
G= Specific gravity of aggregate
Shape Tests• It is desirable that the flakiness index of
aggregates used in road construction is less
than 15% and normally does not exceed 25%.
• Elongation index value in excess of 15% is
considered undesirable.
• Combined Flakiness and Elongation Index shall
not exceed 40 %
Soundness
• To study the resistance of aggregates to
weathering action, by conducting accelerated
weathering test cycle.
Apparatus
• Sodium sulphate or Magnesium sulphate
• Oven
• Weighing balance
• IS sieves
SoundnessProcedure
• In order, to accelerate the effects of
weathering due to alternate wet-dry or freeze-
thaw cycles in the laboratory, the resistance to
disintegration of aggregate is determined by
using saturated solution of sodium sulphate or
magnesium sulphate.
SoundnessProcedure
• Clean, dry aggregates of specified size is
weighed and counted. Then immersed in the
saturated solution of sodium sulphate or
magnesium sulphate for 16 to 18 hours.
• Then the aggregates are dried in an oven at
105-110°C to a constant weight, thus making
one cycle of immersion and drying.
SoundnessProcedure
• The number of such cycles is decided by prior
agreement and then the specimens are tested.
After completing the final cycle, the sample is
dried and each fraction of aggregate is
examined visually to see if there is any
evidence of excessive splitting, crumbling or
disintegration of the grains.
Soundness
• As per IRC, 12% is the maximum
permissible loss in soundness test after 5
cycles with sodium sulphate, for the
aggregate to be used in bituminous surface
dressing, penetration macadam and
bituminous macadam constructions
Coarse Aggregate Specific Gravity
Apparatus• Density basket • Weighing
balance • Water tank • Tray • IS sieves -
10mm & 20mm
Adhesion with Bitumen
• Static immersion test - Very commonly used
as it is quite easy and simple.
• The principle of this type of test is by
immersing aggregate fully coated with the
binder in water maintained at specified
temperature and time and by estimating the
degree of stripping.
Adhesion with Bitumen
• The result is reported as the percentage of
stone surface that is stripped off after the
specified time period.
• IRC has specified the maximum stripping
value as 25 % for aggregate to be used in
bituminous construction like surface dressing,
penetration macadam, bituminous macadam
and carpet when aggregate coated with
bitumen is immersed in water bath at 40°C
for 24 hours.
Polished Stone Value Test
Apparatus
• Accelerated polishing m/c
• Pendulum type friction tester
• Abrading material(sand and emery powder)
• IS sieves:10, 8, 0.425, 0.3, 0.212 & 15mm
• Mould of size
90.5 mm x 44.5 mm
Accelerated Polishing Machine
Wheel Load = 40 kg
Rotation of Load wheel = 320 to 325 rpm.
Period of test = 3 hours
Accelerated Polishing Machine
• The machine is operated for a further period of 3 hours after
releasing emery powder and water at the specified rates
(instead of sand).
• The machine is stopped and test specimens and machine are
cleaned.
PSV Skid Tester (Friction Tester)
Pointer reading: Polished stone value or skid number or friction coefficient in percent
Polishing Stone Value
• For road and bridge works, the polished stone
value of coarse aggregates used in
bituminous concrete, semi dense bituminous
concrete, open graded pre-mix carpet and
close graded premix surfacing of roads,
should be not less than 55 and for the
aggregate used in surface dressing should be
not less than 60.
Sieve AnalysisAnalisis Ayakan
0
10
20
30
40
50
60
70
80
90
100
0.01 0.10 1.00 10.00 100.00
Sieve Size, mm
Per
cent
Pas
sing
, %
Bituminous Materials
• Binder: A material used to hold solid
particles together, i.e. bitumen or tar.
• Bitumen: A heavy fraction from oil
distillation or Last residue obtained from
fractional distillation of Crude Oil. Also
occurs as part of natural asphalt.
What is Bitumen?
• Is a visco-elastic material
Does not have a distinct melting point
Gradually softens when heated
More solid at low temperatures and
more liquid at high temperatures
Is black or dark brown in colour
Has adhesive properties
Has water proofing properties
Forms good bond with variety of aggs.
Natural / Rock / Lake Asphalt
• Naturally occurring Bituminous binder
• Biggest deposits in Trinidad
100 Acres
90 meter deep
10 to 15 Million MT
Pen - 5 max
• Asphalt is found in France, Italy and Switzerland - Rock Asphalt.
Binder Materials
• Tar: A viscous liquid obtained from
distillation of coal or wood. Rarely used in
road construction.
• Coke Oven Tar
Produced at temperatures above 1200OC during manufacturing of coke
High aromatic content
Pitch content - 50 %
• Low Aromatic Tar
Produced at temperatures 600OC to 700OC
Less viscous
Paraffinic in nature
Pitch content - 35 %
Binder Materials
Cutbacks
• This is a liquid form of bitumen.
• They are liquid at low temperatures until
the volatile oil evaporates.
• Due to the release of solvents into the
atmosphere they are now rarely used.
• When bitumen globules are mixed with
water, binders will generally settle out.
• An emulsifier must be added to give a
stable solution.
• When used, the water evaporates and the
bitumen remains on the surface.
• The current types of cold rolled materials
are based on emulsions.
Emulsions
Binder Properties• Adhesion: Bituminous materials adhere to
clean dry surfaces
• Viscosity: All bituminous materials are
viscous, i.e. when subject to a long term
load they deform continuously
• Softening point: This is the temperature at
which the binder softens to a pre-
determined point
Performance Parameters of Binders
• Mix and form a good bond with
aggregate (at high temperature)
• Not melt on the road at highest
atmospheric temperature
• Not crack at extreme low atmospheric
temperature
• Be able to withstand repeated cycles of
loading and unloading
• Be able to withstand repeated cycles of
temperature change
• Not be inflammable
• Be free from impurities
Performance Parameters of Binders
• Bitumen shall be prepared by the refining
of crude petroleum by suitable methods
using appropriate crude or by blending
different crudes or different short residue
to achieve desired properties of paving
grade bitumen conforming to
specifications.
Description of Bitumen
What type of tests do we develop?
• Tests should be simple
• Tests should replicate the actual field
conditions as accurately as possible
• Rate of change of properties with time,
temperature and load should be
measurable or predictable
Tests on Bitumen
1. Penetration test
2. Softening point test
3. Ductility test
4. Viscosity test
5. Specific gravity test
6. Flash and Fire point test
7. Solubility test
8. Thin film oven test
Penetration Test• Arbitrary Empirical
Number
• Depth of penetration of a standard size needle under standard test conditions
• An indirect method of measuring viscosity
• The test measures the hardness or softness of bitumen in terms of penetration
Penetration test
• Bitumen is softened to a pouring consistency
and is poured into the container to a depth at
least 10 mm in excess of the expected
penetration.
• The penetration sample is cooled for 90 min in
air (15 to 300C) and then for 90 min in water
bath (250C) before testing.
Penetration Test
• Temperature = 250C
• Load on needle = 100 g
• Time in which penetration
is recorded = 5 s
• The penetration is
measured by a graduated
dial (in 1/10th of mm)
Penetration test
• A bitumen is referred to as 70 pen if the
penetration is 7 mm.
• A grade of 40/50 bitumen means the
penetration value is in the range 40 to 50 at
standard test conditions.
Penetration test
• In cold regions, bitumen with High penetration
value is used.
• In warm regions, bitumen with low
penetration value is used ex. 30/40 grade.
• The factors which affect the Penetration test is
test temperature, needle size and weight and
period of cooling.
Softening Point Test• The softening point is the temperature at
which the substance attains a particular
degree of softening under specified
condition of test.
• A viscous material like bitumen or tar
doesn’t have a well defined softening point.
• The test determines the temperature at
which a standard ball will pass through a disc
of bitumen contained in ring.
Softening Point Test
• Arbitrary test to indicate the temperature atwhich bitumen is more of a liquid and less of asolid
Softening Point TestBrass rings• Inside dia• 17.5 mm at top• 15.9 mm at bottom• Outside dia• 20.6 mm• Depth 6.4 mm
• Steel balls – Dia 9.5 mm and mass 3.5 g
• Distance between bottom of the ring and
top surface of the bottom plate is 25mm
Softening Point TestGlass container
• Dia 85 mm
• Depth 120 mm
The bitumen is heated
to pouring consistency
and poured into ring
and cooled for half an
hour before testing.
Softening Point Test
Arrrangement
• Specimen in steel rings
• Steel Balls in Ball Guides
• Water or Glycerin
Softening Point Test
The liquid medium
is then heated at a
rate of 50C increase
per minute.
With increase in temperature bitumen melts
and come down with the weight of ball
The temperature at which the steel balls
touches the bottom plate is noted
Softening Point test
• Higher softening points indicate higher
resistance to melting on pavement.
• Higher resistance to melting indicates
higher rutting resistance.
• Higher softening point indicates lower
temperature susceptibility and is
preferred in warm climates.
Ductility Test• In flexible pavement construction it is
important that the binders form ductile thin
film around the aggregate.
• This serves as a satisfactory binder in improving
the physical interlocking of the aggregate
bitumen mixes.
• Under traffic loads the bitumen layer is
subjected to repeated deformation and
recoveries.
Ductility Test• The binder material which does not possess
sufficient ductility would crack and thus
provide pervious pavement surface.
• The test is believed to measure the adhesive
property of bitumen and its ability to stretch.
• The ductility of a binder is an indication of its
elasticity & ability to deform under load &
return to original condition upon removal of
the load.
Ductility Test
• A material which doesn’t possess adequate
ductility would crack under a load.
• This is unsatisfactory since water can penetrate
into the surfacing through there cracks.
• The property is determined by conducting the
ductility test using a standard briquette of
bitumen.
Ductility Test
• The briquette mould is filled with bitumen and
cooled for 30 min in air and 30 min in water
before testing.
Ductility Test
• Then it is fixed to expanding machine assembly
which stretches the bitumen at a rate of
5cm/min
Ductility Test
• The stretching is continued and the bitumen
specimen expands till it breaks.
• This point is noted by the reading on the scale.
Ductility Test
• Ductility is defined as the distance that a
standard briquette of bitumen, necked to a
cross section of 1 sq-cm, will stretch without
breaking when elongated at a rate of 5
cm/min at 270C.
• Minimum ductility value - 50 cm as per IS.
• Viscosity is the property of a fluid that
determines the resistance offered by the fluid
to a shearing force under laminar flow
conditions, it is thus the opposite of fluidity.
• At the application temperature, viscosity
greatly influences the strength of resulting
paving mixes.
Viscosity Test
• Low or high viscosity during mixing or
compaction has been observed to result in
lower stability values.
• At high viscosity, it resists the compactive effort
and thereby resulting mix is heterogeneous,
hence low stability values.
• At low viscosity instead of providing a uniform
film over aggregates, it will lubricate the
aggregate particles.
Viscosity Test
Absolute or Dynamic Viscosity (Newtonian Liquid)
It is an internal friction, such that if a tangential
force of one dyne (0.00001 N) acting on planes of
unit area separated by unit distance of the liquid
produces unit tangential velocity, the CGS unit for
the viscosity of the liquid is 1 Poise.
Viscosity Test
Viscometer - Capillary type made of borosilicate
glass, annealed suitable for this test
• Cannon-Manning Vacuums Viscometer
• Asphalt Institute Vacuum Viscometer
• Modified Koppcrs Vacuum Viscometer
Viscosity Test
e
Cannon-Manning Vacuums Viscometer
The size numbers/approximate bulb factors K,
and viscosity ranges are as follows:
Cannon-Manning VacuumsViscometer
• For all viscometer sizes the
volume of measuring bulb
C is approximately three
times that of bulb B.
• The viscosity ranges
correspond to a filling time
of 60 and 400 s for both
measuring bulbs.
Cannon-Manning Vacuums Viscometer
Water Bath –• A suitable water bath for immersion of the
viscometer so that the liquid reservoir or topof the capillary, whichever is uppermost is atleast 20 mm below the upper bath level, andwith a provision for the visibility of theviscometcr and the thermometer.
• Firm support for the viscomrter shall beprovided. The accuracy of the viscometer bathshould be ± 0.10 C over the entire length of theviscometer.
Cannon-Manning Vacuums Viscometer
Vacuum System –A vacuum system capable of maintaining avacuum to within ± 0.05 cm of the desired levelup to and including 30 cm of mercury. The glasstubing of 6.35 mm diameter and all glass jointsshould be completely airtight and no loss ofvacuum should be permitted till the experiment ison. A vacuum or aspirator pump is suitable forthe vacuum source.
Cannon-Manning Vacuums Viscometer
Procedure –Conduct similar test on the sample and find thevalue of time t.
Calculate the absolute viscosity to three
significant figures, by the following equation:
Viscosity Poises = K t
Where K = selected calibration factor, in poise per
second; and
t = flow time in seconds
Cannon-Manning Vacuums Viscometer
Always report the test temperature and vacuum
with the viscosity test results.
For example, viscosity at 6O0C, 30 cm Hg Vacuum
in poises
Cannon-Manning Vacuums Viscometer
Kinematic Viscosity
• The CGS unit of kinematic viscosity is the stoke
which has the dimensions square centimetre
per second.
• For petroleum products the kinematic viscosity
is generally expressed in centistokes (cSt)
which is l/lOOth of a stoke.
Cannon-Manning Vacuums Viscometer
Viscosity Ratio —
• It is the ratio of viscosity of residue from rolling
thin film oven test to unaged bitumen, both
measured at 60°C.
• Specific gravity value is required for conversion
of weight to volume.
• Specific gravity of a binder is needed during mix
proportioning.
• SG of bitumen varies from 0.97 to 1.02.
• SG of tar varies from 1.16 to 1.28.
Specific Gravity Test
There are two methods to test the specific gravity
of bitumen
• Pyknometer method
• Balance method
Generally balance method is used
• Cubical specimens of side 20 mm are used to
find the SG.
Specific Gravity Test
• The mass of the dry specimen when cooled at
270C is noted ‘a’.
• The mass of the speciment when immersed in
distilled water is noted ‘b’.
• Specific gravity of bitumen = a/(a-b)
• High value of specific gravity suggests impurity
in bitumen.
Specific Gravity Test
• When a bituminous binder is heated
continuously it starts emitting volatile
vapours (hazardous) above a certain
temperature.
• These volatile vapours can momentarily
catch fire in form of flash and on continued
heating will catch fire.
Flash and Fire Point Test
• It is essential that the bitumen qualifies
these temperatures before use.
• The flash point of bitumen is that
temperature at which it gives off vapours,
which ignite when exposed to flame, but
does not continue to burn.
• The flash point is an indication of critical
temperature at & above which suitable
precautions should be taken to eliminate fire
hazards.
Flash and Fire Point Test
• Pensky-Mortins Tester - BIS.
• The method involves a cup into which the
bitumen is filled.
• The bitumen sample is then heated at a rate
of 5-60C/min stirring the material
continuously.
• The surface is exposed to test flame at
regular intervals.
Flash and Fire Point Test
• The flash point is taken at the temperature
read on the thermometer when flame
causes a bright flash on the surface of
material.
• It is in the range of 2200C.
Flash and Fire Point Test
• If heating is continued beyond the flash
point, the vapours ignite in the presence of
the flame and will continue to burn.
• Fire point is that temperature at which the
surface catches file and burns continuously
for five seconds.
• The presence of water will spread the
bitumen fire.
Flash and Fire Point Test
• All bitumen are substantially soluble in
Carbon-di-sulphide and Carbon tetra chloride.
• Hence any impurity in bitumen in the form of
inert minerals, carbon, salts etc. could be
quantitatively analysed by dissolving the
samples of bitumen in any one of the two
solvents.
Solubility Test
• A sample of 2g of bitumen is dissolved in
100 ml of solvent and filtered.
• The insoluble material is washed, dried and
weighed.
• It is expressed in percentage of original
sample.
• The IS specifications require 99% solubility.
Solubility Test
• A sample of bitumen is subjected to
hardening conditions as would be expected
during hot mixing operations.
• A 50 ml sample of bitumen is placed in a flat
bottomed sample pan 140mm inside
diameter & 10mm deep, the weighed
sample & container are placed in a shelf
which rotates at 5 to 6 rpm for 5 hrs in a
ventilated oven maintained at 1630C.
Thin Film Oven Test
• The loss in weight of the sample is expressed
as percentage of the original weight.
• This method is used to identify short term
aging or hardening of bitumen.
Thin Film Oven Test
• To simulate the short-term aging of asphalt
binders that occurs during the hot-mixing
process.
• Use this test to calculate the change in
sample mass on heating, but its main
function is to produce an aged material for
analysis by other suitable means.
Rolling Thin Film Oven Test
Apparatus• Rolling thin film oven (RTFO), with a flow
meter and thermometer
• Eight sample containers (RTFO bottles)
• Balance
• Spatula or other tool, sufficiently shaped to
scrape material from the inside of the RTFO
bottles
• Sample dishes, tins, or cups, for collecting
aged material at the end of the test.
Rolling Thin Film Oven Test
Key Parameters• Position of air nozzle outlet from the mouth
of sample containers – 6.4 mm
• Position the thermometer so that its bulb is
with 25 mm of the same height as the center
of the carriage
• Time – 85 ± 5 min
• Temperature – 163 ± 0.5°C
• Rotation speed of the carriage – 15 ± 0.2 rpm
• Air flow to the oven – 4 ± 0.2 L/min
Rolling Thin Film Oven Test
Procedure
• Heat the asphalt binder sample to 163°C in a
oven until it is completely fluid and pourable
• Remove the sample from the oven and
briefly stir with a clean spatula
• If measuring mass change, weigh the two
empty mass-change bottles to the nearest
0.001 g and record the results
Rolling Thin Film Oven Test
Procedure• Pour 35 ± 0.5 g of asphalt into a sample
bottle
• Place the bottle on its side and roll it over to
spread the material around the inside
• Repeat the above procedure for the second
bottle
• Set the mass-change bottles aside and allow
them to cool
Rolling Thin Film Oven Test
Procedure• Pour 35 ± 0.5 g of asphalt into a sample
bottle
• Place the bottle on its side and roll it over to
spread the material around the inside
• Repeat the above procedure for all other
samples
• When the mass-change bottles have cooled,
weigh to the nearest 0.001 g
Rolling Thin Film Oven Test
Procedure• Load the sample bottles in the sample
carriage as soon as possible after pouring
• Start the test within 5 min. of loading the
samples into the carriage and evenly
distribute all bottles around the carriage
• If measuring mass change, remove the
previously weighed bottles from the oven,
and place them on their sides to cool down
Rolling Thin Film Oven Test
• Viscosity Ratio — It is the ratio of viscosity of
residue from rolling thin film oven test to
unaged bitumen, both measured at 60°C.
GRADES of Bitumen
• Bitumen shall be classified into four grades
based on the viscosity, and suitability
recommended for maximum air temperature.
IS 73 : 2013 PAVING BITUMEN — SPECIFICATION
IS 73 : 2013 PAVING BITUMEN — SPECIFICATION
Grade Suitable for 7 day AverageMaximum Air Temperature °C
VG10 < 30
VG20 30 - 38
VG30 38 - 45
VG40 > 45
NOTE — This is the 7 day average maximumair temperature for a period not less than 5years from the start of the design period.
IS 73 : 2013 PAVING BITUMEN — SPECIFICATION
REQUIREMENTS
• The paving bitumen binder shall be
homogenous and shall not foam when
heated to 175°C.
• The various grades of bitumen shall
conform to the requirements prescribed in
Table 1 of IS 73.
IS 73 : 2013 PAVING BITUMEN — SPECIFICATION
Requirements for Paving Bitumen
Penetration at 25°C, 100 g, 5 s, 0.1 mm, Min
Grade Penetration
VG10 80
VG20 60
VG30 45
VG40 35
Method of test - IS 1203
IS 73 : 2013 PAVING BITUMEN — SPECIFICATION
Requirements for Paving Bitumen
Absolute viscosity at 60°C, Poises
Grade Penetration
VG10 800 - 1200
VG20 1600 - 2400
VG30 2400 - 3600
VG40 3200 - 4800
Method of test - IS 1206 (Part 2)
IS 73 : 2013 PAVING BITUMEN — SPECIFICATION
Requirements for Paving Bitumen
Kinematic viscosity at 135°C, cSt, Min
Grade Penetration
VG10 250
VG20 300
VG30 350
VG40 400
Method of test - IS 1206 (Part 3)
IS 73 : 2013 PAVING BITUMEN — SPECIFICATION
Requirements for Paving Bitumen
Kinematic viscosity at 135°C, cSt, Min
Grade Penetration
VG10 250
VG20 300
VG30 350
VG40 400
Method of test - IS 1206 (Part 3)
IS 73 : 2013 PAVING BITUMEN — SPECIFICATION
Requirements for Paving Bitumen
Solubility in trichloroethylene, percent, Min
Grade Penetration
VG10 99.0
VG20 99.0
VG30 99.0
VG40 99.0
Method of test - IS 1216
IS 73 : 2013 PAVING BITUMEN — SPECIFICATION
Requirements for Paving Bitumen
Softening point (R&B), °C, Min
Grade Penetration
VG10 40
VG20 45
VG30 47
VG40 50
Method of test - IS 1205
IS 73 : 2013 PAVING BITUMEN — SPECIFICATION
Requirements for Paving BitumenTests on residue from rolling thin film oventest: Viscosity ratio at 60°C, Max
Grade Penetration
VG10 4.0
VG20 4.0
VG30 4.0
VG40 4.0
Method of test - IS 1206 (Part 2)
IS 73 : 2013 PAVING BITUMEN — SPECIFICATION
Requirements for Paving BitumenTests on residue from rolling thin film oventest: Ductility at 25°C, cm, Min
Grade Penetration
VG10 70
VG20 50
VG30 40
VG40 25
Method of test - IS 1208