Definition and difference between bitumen and Tar

Definition and difference between bitumen and Tar – Advantages and disadvantages of Bitumen

by

 

DEFINITION AND DIFFERENCE BETWEEN BITUMEN AND TAR 

 BITUMEN AND TAR:

Definition and difference between bitumen and Tar
Difference between bitumen and tar

Origin, preparation, properties and chemical
constitution of bituminous road binders; requirements,  Bituminous binders used in pavement
construction works include both bitumen and tar. Both bitumen and tar have
similar appearance, black in colour though they have different characteristics.
The
source of road bitumen is either formed from petroleum or by natural processes
as a result of geological forces.

BITUMEN is a
petroleum product obtained by the distillation of petroleum crude. The refining of petroleum is most
complex procedure producing a tremendous range of products from the simplest
hydrocarbon gas methane to the hardest bitumen with constituents of molecular
weight of the order of several thousands.

TAR
is a thermoplastic material obtained from the destructive distillation.

            The
grade of bitumen used for pavement construction work of roads and airfields are
called paving grades and used for water proofing of structures and industrial
floors etc. are called industrial grades.

The viscosity of bitumen is reduced some times by a
volatile diluents this material is called Cutback. The bitumen is
suspended in a finely divided condition in an aqueous medium and stabilized
with an emulsifier; the material is known as Emulsion.

Difference between
Bitumen and Tar


Bitumen
Tar
Bitumen if found in black to brown
in color
Tar is usually found in brown
colour
Bitumen is soluble in carbon
disulphide and carbon tetra chloride
Tar is soluble in toluene
Bitumen is obtained from
fractional distillation of crude oil
Tar is obtained by destructive
distillation of coal or wood
Bitumen consists of large amount
of aromatic hydrocarbon
Tar consist of large amount of
oily matter with lower molecular weight
Bitumen show resistance to coating
road aggregate and also does not retain in presence of water
Tar coats more easily and retain
it better in presence of water
Free carbon content is less
Free carbon content is more
It shows more resistance to
weathering action
It shows less resistance to
weathering action
Less temperature susceptibility
More temperature susceptibility
Molecular weight range for road
bitumen is 400 to 5000
Molecular weight range for road
tar is 150 to 3000

ADVANTAGE AND DISADVANTAGE OF BITUMEN

Advantages of Bituminous Road Pavement:

·        
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

·        
Generally bituminous road do not develop
cracks on the surface for long period.

·        
Maintenance cost of this road is also
very less.

·        
Bituminous road are waterproof,
non-slippery, smooth, durable and it provides comfortable road surface for the
traffic.

·        
It can withstand the adverse natural
effects caused by heavy rain, excess heat and change in temperature.

·        
Better adhesion between aggregates and
binder

·        
Bituminous pavements offer high skid
resistance and provide high contrast in color between bituminous pavement and
road markers, giving driver better road visibility in any weather condition.


Disadvantages of Bituminous
Road Pavement:

·     Environment
get polluted during preparing mix.

·     Impurities
present in bitumen also effect the soil, it contain hydrocarbon which effect
the ground water.

·     Bituminous
pavement is less durable.

·     Low
tensile strength.

·     If
the bituminous material is used in excess than the value for given mix, it
effects the performance of the bituminous road.