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DUCTILITY of Bitumin

Updated: May 1, 2020


To determine the ductility of distillation residue of cutback

bitumen, blown type bitumen and other bituminous products as

per IS: 1208 - 1978.


The ductility of a bituminous material is measured by the

distance in cm to which it will elongate before breaking when a

standard briquette specimen of the material is pulled apart at a

specified speed and a specified temperature.



i) Standard mould

ii) Water bath

iii) Testing machine

iv) Thermometer - Range 0 to 44oC, Graduation 0.2oC


i) Completely melt the bituminous material to be tested by

heating it to a temperature of 75 to 100oC above the

approximate softening point until it becomes thoroughly fluid.

Assemble the mould on a brass plate and in order to prevent

the material under test from sticking, thoroughly coat the

surface of the plate and the interior surfaces of the sides of

the mould with a mixture of equal parts of glycerine and

dextrin. While filling, pour the material in a thin stream back

and forth from end to end of the mould until it is more than

level full. Leave it to cool at room temperature for 30 to 40

minutes and then place it in a water bath maintained at the

specified temperature for 30 minutes, after which cut off the

excess bitumen by means of a hot, straight-edged putty

knife or spatula, so that the mould is just level full.

ii) Place the brass plate and mould with briquette specimen in

the water bath and keep it at the specified temperature for

about 85 to 95 minutes. Remove the briquette from the

plate, detach the side pieces and the briquette immediately.

iii) Attach the rings at each end of the two clips to the pins or

hooks in the testing machine and pull the two clips apart

horizontally at a uniform speed, as specified, until the

briquette ruptures. Measure the distance in cm through

which the clips have been pulled to produce rupture. While

the test is being done, make sure that the water in the tank

of the testing machine covers the specimen both above and

below by at least 25mm and the temperature is maintained

continuously within ± 0.5oC of the specified temperature.


A normal test is one in which the material between the two clips

pulls out to a point or to a thread and rupture occurs where the

cross-sectional area is minimum. Report the average of three

normal tests as the ductility of the sample, provided the three

determinations be within ± 0.5 percent of their mean value.

If the values of the three determinations do not lie within ± 0.5

percent of their mean, but the two higher values are within ± 0.5

percent of their mean, then record the mean of the two higher

values as the test result.

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