Contents

Introduction

Types

Properties

Tests on Bitumen

Grading of Bitumen

Introduction

Used in pavements

Binding material

Used in

wearing course

Primer

Patch works

Surface dressing etc.,

Bitumen, Tar are not same.

Bitumen and Tar

Black or dark colored solid, viscous

cementitious substance.

Bitumen is petroleum product – obtained

by distillation of crude petroleum or

naturally available in asphalt.

Coal tar – by product in destructive

distillation of coke

Bitumen and Tar

Bitumen

Excellent Binding properties

Good water proofing surface

Tar

Highly temperature susceptible

Pollutant

Poor adhesion in presence of water

Bitumen preferred over Tar

Bitumen - Definition

According to ASTM -

“Bitumen is hydrocarbon material of either

natural or pyrogenous origin found in

gaseous, liquid, semi-solid or solid form

and is completely soluble in carbon-di-

sulphide , carbon tetra chloride”

Bitumen - Intro

Definition

At normal range of temp – semi solid state

When heated viscosity decreases

For construction of pavements – heated

from 130 to 175C

Mixing with aggregates at high temp – Hot

bituminous mix

Mixing with aggregates at low or normal

temperature – Cold bituminous mix

Grades of Bitumen

Bitumens can be majorly classified into

2 types

Paving grade bitumen: Used for construction

of roads and airfields

Industrial grade bitumen: water proofing of

structures and industrial floors etc.,

Types

Paving grade bitumen

Modified bitumen binders

Cutback bitumen

Bitumen Emulsion

Cutback bitumen

To have fluid consistency at normal

temp, with low heating – cutback

bitumen is used

Dilution of paving grade in volatile

solvents – kerosene, light fuel oil etc.,

Hardening rate depends on the grade

and characteristics of bitumen and

solvent.

RC, MC, SS

Cutback bitumen

RC is recommended for surface

dressing and patchwork.

MC is recommended for premix with

less quantity of fine aggregates.

SS is used for premix with appreciable

quantity of fine aggregates.

Bitumen Emulsion

To get fluid consistency

Dispersing bitumen globules in aqueous solution (i.e., water with dispersing agent)

60% water, remaining bitumen

Cold bituminous mix

Properties depend on grade, water quantity, emulsifier

RS, MS, SS

Modified Bitumen Binders

To improve the properties of bitumen

Additives are mixed

Polymer modified bitumen is used only

in wearing course depending on the

severity of climatic and weather

conditions

Advantages of modified

bitumen Lower susceptibility to daily and seasonal

temperature variations

Higher resistance to deformation at high pavement temperature

Better age resistance properties

Higher fatigue life for mixes

Better adhesion between aggregates and binder

Prevention of cracking and reflective cracking

Functions of Binders

Used in surface course

Used in base course depending on traffic

Used in preparation of mixes

Used as prime coat over granular base course

Used in soil stabilization

Sealer material for filling joints, cracks in cc pavements

Requirements

Adequate viscosity Heating bitumen, aggregate

Cutback

Emulsion

Sufficiently viscous on cooling – compact surface with no deformation

Form thin film around aggregates Sufficient ductility

Temp susceptibility

Adhesion with aggregates in presence of water

affinity between the materials used in the mix

Tests on Bitumen

Penetration test

Ductility test

Softening point test

Specific gravity test

Viscosity test

Flash and fire point test

Float test

Water content test

Loss on heating test

Penetration test

Measures hardness or softness of

bitumen

Measures penetration depth in tenths of

a millimeter to which a standard loaded

needle will penetrate in 5 sec

Standardized equipment – BIS

Penetrometer device – consists a

needle, weight of 100g, device for

releasing and locking position

Penetration test setup – Rough

diagram

Penetrometer

Bitumen heated to pouring consistency

Placed in containers to a depth i.e., min15mm excess of expected penetration

Conducted at 25C

Highly fluctuated with small inaccuracy

Results are used for grading the bitumen i.e., 40/50 or 80/90 etc., bitumens

Ductility test

It is the property that permits bitumen to

undergo great deformation without

breaking

Ductility is defined as the distance in cm,

to which a standard sample or briquette

of the material will be elongated without

breaking

The bitumen sample is heated and

poured in the mould assembly placed on

a plate

Cooled in air and then kept in waterbath

at 27C

Sides are removed

Attached to a machine

Minimum ductility is 75cm

Ductility Mould

Softening point test

Ring and Ball

Temperature at which the bitumen attains a

particular degree of softening

Brass Ring containing test sample

Suspended in liquid (water, glycerin etc.,)

Heating @5C/Min

Softening point denotes the temp at which

bitumen touches the base metal plate.

Specific Gravity Test

Used for classification

Density influenced by chemical

composition

Using pycnometer method or any other

standard method

0.97 to 1.02

Viscosity Test

It is fluid property of bitumen

Measure of resistance to flow

Influences the strength of resulting mixes

Very low and high viscosity decreases the stability of mix

High viscosity – non homogenous mix

Low viscosity – no uniform film on aggregates, just lubricates

Orifice type viscometer and other types of equipment is used Time noted for receiving specific quantity of bitumen

material through orifice

Flash and Fire point test

High temperatures – Bitumen leaves volatiles

These are inflammable

Important to know at where it catches fire

According to BIS, flash point is the temperature at which the vapour of the bitumen momentarily catches fire in the form of flash.

Fire point is the temperature at which the material gets ignited and burns

Flash point should be min 175C

Water content test

Bitumen distilled in petroleum

Heated

Wait of water condensed and collected

is expressed as the percentage by

weight of original sample

Allowable maximum water content

should not be more than 0.2% by weight

Loss on Heating Test

Bitumen loses volatility upon heating and gets hardened

50gms of sample is weighed and heated to 163C for 5 hours

Sample weighed after heating

Loss in weight is expressed as the percentage by weight of the original sample.

For paving mixes not more than 1% is allowed

How ever, if the bitumen has penetration values of 150 -200mm 2% is allowed.

Thankyou