Pavement Materials - Sri Jayachamarajendra College of...

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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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

Pavement Material Aggregates

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.

Natural Aggregates

Three Types

Igneous rocks

Sedimentary rocks

Metamorphic rocks

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

Sedimentary rocks• Kankar

Soft to medium hard

Good for sub-base and base courses

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.

Desirable Properties

• Strength

• Hardness

• Toughness

• Durability

• Shape

• Adhesion with bitumen

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



15 Blows


• 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


• IS sieves

12.5, 10 & 2.36 mm

• Steel Tamping Rod

• Compression testing machine

ACV - Process


Aggregate Crushing Value - Process

Compressive load 40 tonnes

• Weight of aggregates taken = W1

• Weight of aggregates retained on 2.36 mm

sieve = W2

• Aggregate Crushing Value = W2/W1 x 100


• 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.


Los Angeles Abrasion TestApparatus

• Los Angles Abrasion M/c

• Steel balls - 11no.


• 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



• 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 %


• 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

• Equi-dimensional aggregates

• Flat Aggregates

• Elongated Aggregates

Shape Tests

• Flat Aggregates – Flakiness Index

• Elongted Aggregates – Elongation Index

• Equi-dimensional Aggregates – Angularity Number

Flakiness IndexApparatus

• Thickness gauge


• 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

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


• 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

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.


• 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


• 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

Before After

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.

Polished Stone Value Sample Preparation

PSV Sample

PSV Polishing

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.

Splitter

Sieve Set

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

, %

Pavement Material Bitumen

Pavement Construction

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

Ring and ball apparatus

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.


• 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.


Arrrangement

• Specimen in steel rings

• Steel Balls in Ball Guides

• Water or Glycerin


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

Briquette mould

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

• Kinematic Viscosity

• Viscosity Ratio

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.


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.


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.


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


Always report the test temperature and vacuum

with the viscosity test results.

For example, viscosity at 6O0C, 30 cm Hg Vacuum

in poises


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.


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.


• 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.


• 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.


• 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.


• 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.


• 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.


• 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

Thin Film Oven Test

Oven Tester

• 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

Thin Film Oven Test

3 Containers140 mm dia10 mm deep

1 Shelf

5 to 6 rpm5 hrs1630C

• 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.




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


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


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


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


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


• 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


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.


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.


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



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)



Kinematic viscosity at 135°C, cSt, Min

Grade Penetration

VG10 250

VG20 300

VG30 350

VG40 400




Kinematic viscosity at 135°C, cSt, Min

Grade Penetration

VG10 250

VG20 300

VG30 350

VG40 400




Solubility in trichloroethylene, percent, Min

Grade Penetration

VG10 99.0

VG20 99.0

VG30 99.0

VG40 99.0




Softening point (R&B), °C, Min

Grade Penetration

VG10 40

VG20 45

VG30 47

VG40 50



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



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


Modes of Failure

Rutting/ Permanent Deformation

Fatigue Cracking

Low Temperature Cracking

• Cracking of thin surface

Thank you

Date post:	04-Aug-2018
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