Determining the Ductility Of Bitumen

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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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  • Nilotpal Sengupta August 27, 2009 at 5:24 am

    Why ductility of bitumen needs to be determined?

    What is the engineers interest for doing this test?

    • MANISH July 26, 2010 at 12:57 pm

      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 November 25, 2009 at 11:44 pm

    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

  • ANSHUMAN August 10, 2010 at 12:02 pm

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

    • deny August 16, 2012 at 6:58 am

      be careful…

  • samuel alehegn August 25, 2010 at 8:10 am

    what are the factors affecting the ductility test result?

    • KABIR April 18, 2011 at 5:01 pm

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

  • samuel alehegn August 25, 2010 at 8:15 am

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

    • Safia Hasan April 12, 2011 at 2:29 am

      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 May 23, 2011 at 3:42 am

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

  • vijaya March 8, 2011 at 11:15 am

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

    • Kazuko February 9, 2012 at 10:36 am

      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 November 5, 2011 at 3:54 am

    why is water used in this experiment?

    • sudiksha uprety August 2, 2013 at 9:19 pm

      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 November 2, 2015 at 10:31 am

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

  • saeed December 8, 2011 at 4:16 am

    ductility of bitumen

  • pradishnarayanan April 9, 2012 at 4:48 am

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

  • Milan sapakota July 29, 2012 at 4:30 am

    why ductility test is necessary?

  • sudiksha uprety August 2, 2013 at 9:20 pm

    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 November 29, 2014 at 10:33 pm

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

  • khuram shahzad May 25, 2016 at 10:53 pm

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

  • dian rc November 4, 2016 at 10:49 pm

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

  • khalil gujjar July 26, 2017 at 12:03 am

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

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