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Determining the Ductility Of Bitumen

This test is done to determine the ductility of distillation residue of cutback bitumen, blown type bitumen and other bituminous products as per IS: 1208 – 1978. The principle is : 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.

The apparatus required for this test:
i) Standard mould
ii) Water bath
iii) Testing machine
iv) Thermometer – Range 0 to 44oC, Graduation 0.2oC


Procedure to determine the Ductility Of Bitumen
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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Kanwarjot Singh

Kanwarjot Singh is the founder of Civil Engineering Portal, a leading civil engineering website which has been awarded as the best online publication by CIDC. He did his BE civil from Thapar University, Patiala and has been working on this website with his team of Civil Engineers.

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25 comments on "Determining the Ductility Of Bitumen"

Nilotpal Sengupta says:

Why ductility of bitumen needs to be determined?

What is the engineers interest for doing this test?

MANISH says:

actually a layer of bitumen is spread over the sub surface grade layer .if the bitumen is ductile only then it can be heated to temperature of around 70 degree celcius and can be mixed with the sublayer.
from engineers point of view it is important otherwise if bitumen is not ductile then it can break during summers and there will be cracks on the road.

hemanth says:

Ductility of bitumin is required to know how longer lt can spread while we pouring the bitumin……higher the ductility more area can be covered


Ductility is a measure of Breaking resistance or Cracking resistance of a Bitumen During Summer.

deny says:

be careful…

samuel alehegn says:

what are the factors affecting the ductility test result?

KABIR says:

The ductility value gets affected by factors such as pouring temperature, test temperature, rate of pulling etc.

samuel alehegn says:

why it is necessary to add either methyl alcohol or sodium chloride in the testing bath?

Safia Hasan says:

to maintain a certain specific gravity. otherwise, when the bitumen specimen is being pulled apart and it becomes thin, it may float or fall

sameer ali says:

add a little bit of salt to the water in which dutility is carried out

vijaya says:

even if the specific gravity of the bitumen is more than 1, the penetration does not satisfy in some cases why

Kazuko says:

Manipal and JSS uivsernity may be the esteemed organizations for PG in Pharmacy and BITS Mesra is no way less than the above for AICTE grants, alumni and research.

chandra says:

why is water used in this experiment?

sudiksha uprety says:

its done in order to maintain temperature.if temperature gets fluctuated then hot/cold water is added to maintain it coz temperature plays vital role in this experiment.

Saurav Sadhukhan says:

To ensure that the bitumen doesn’t stick to the test apparatus

saeed says:

ductility of bitumen

pradishnarayanan says:

please add quality checking methods ,about materials and construction.also include the details of refinery related engineering works

Milan sapakota says:

why ductility test is necessary?

sudiksha uprety says:

its done in order to maintain temperature.if temperature gets fluctuated then hot/cold water is added to maintain it because temperature plays vital role in this experiment.

Rawaa says:

how much salt should i add to the water ?
why does some bitumen have low or high ductility ?

khuram shahzad says:

if we have to check ductility in both direction which apparatus is used for???

dian rc says:

i did this test a couple days ago but my bitumen did not rupture. what does this indicate?

khalil gujjar says:

assalam o allikum plz tell me any one how to maximum standard bitumen ductility reading.

sahan lakmal says:

what is the importance of the ductility test for binder selection?

sahan lakmal says:

What are the limitations of the ductility tests? How can you overcome this problem?

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