Softening point test on Bitumen


To determine the softening point of asphaltic bitumen and fluxed native asphalt, road tar, coal tar pitch and blown type bitumen as per IS: 1205 – 1978.



i) Ring and ball apparatus
ii) Thermometer – Low Range : -2 to 80ºC, Graduation 0.2ºC
                                – High Range : 30 to 200ºC, Graduation 0.5ºC


i) The sample should be just sufficient to fill the ring. The excess sample should be cut off by a knife.
ii) Heat the material between 75 and 100ºC. Stir it to remove air bubbles and water, and filter it through IS Sieve 30, if necessary.
iii) Heat the rings and apply glycerine. Fill the material in it and cool it for 30 minutes.
iv) Remove excess material with the help of a warmed, sharp knife.


A) Materials of softening point below 80ºC:

i) Assemble the apparatus with the rings, thermometer and ball guides in position.
ii) Fill the beaker with boiled distilled water at a temperature 5.0 ± 0.5ºC per minute.
iii) With the help of a stirrer, stir the liquid and apply heat to the beaker at a temperature of 5.0 ± 0.5ºC per minute.
iv) Apply heat until the material softens and allow the ball to pass through the ring.
v) Record the temperature at which the ball touches the bottom, which is nothing but the softening point of that material.

B) Materials of softening point above 80ºC:

The procedure is the same as described above. The only difference is that instead of water, glycerine is used and the starting temperature of the test is 35ºC.


Record the temperature at which each ball touches the bottom. An average value of two tests is reported as softening point value.


  1. Use glycerin for remove of bitumen from the container.
  2. Use distilled water in test for accuracy result.
  3. Equipment should be cleaned thoroughly before testing & after testing.


Softening point denotes the temperature at which the bitumen attains a particular degree of softening under specified condition of test. 

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