Penetration test of Bitumen


To determine the penetration of bitumen as per IS: 1203 – 1978.


The penetration of a bituminous material is the distance in tenths of a mm, that a standard needle would penetrate vertically, into a sample of the material under standard conditions of temperature, load and time.


Related image

i) Penetrometer
ii) Water bath
iii) Bath thermometer – Range 0 to 44oC, Graduation 0.2oC


Bitumen should be just sufficient to fill the container to a depth of at least 15mm in excess of the expected penetration.


i) Soften the bitumen above the softening point (between 75 and 100oC). Stir it thoroughly to remove air bubbles and water.
ii) Pour it into a container to a depth of at least 15mm in excess of the expected penetration.
iii) Cool it at an atmospheric temperature of 15 to 30oC for 90 minutes . Then place it in a transfer dish in the water bath at 25.0 + 0.1oC for 90 minutes 
iv) Keep the container on the stand of the penetration apparatus.
v) Adjust the needle to make contact with the surface of the sample.
vi) Adjust the dial reading to zero.
vii) With the help of the timer, release the needle for exactly 5 seconds.
viii) Record the dial reading.
ix) Repeat the above procedure thrice.


The value of penetration reported should be the mean of not less than three determinations expressed in tenths of a mm.


  1. If the sample contains extraneous matter, it should be sieved through I.S. Sieve 30
    (IS: 460-1962).
  2. The needle should be cleaned with benzene and dried before penetration.
  3. To avoid over heating at the bottom of the container, use of an air oven or sand
    bath is recommended.
  4. While the needle is penetrating into the sample, if there is any movement of the
    container, that determination shall be discarded.
  5. Equipment should be cleaned thoroughly after testing.


It measures the hardness or softness of bitumen by measuring the depth in tenths of a millimeter to which a standard loaded needle will penetrate vertically in 5 seconds.

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