Determination Of Penetration Value of Bitumen


  • IS: 1203- 1978


  • Penetration of a bituminous material is the distance in tenths of a millimeter that standard needle will penetrate vertically into a sample under standard conditions of temperature, load and time.


  • Standard Penetration apparatus
  • A metal or glass cylindrical flat-bottomed container essentially with the following dimensions
    For penetration below 225
    Diameter 55 mm
    Internal depth 35 mm
    For penetration between 225 and 350
    Diameter 70 mm
    Internal depth 45 mm
  • Needle shall be made up of straight, highly polished, cylindrical, hard steel rod.
  • Water bath 10 liters capacity thermostatically Controlled and maintained within the temperature of  25 ± 0.1°C.
  • Thermometer capable of reading temperature up to 250 °C.


  • Soften the material to a pouring consistency at a temperature not more than 60 °C for tars and pitches and not more than 90 °C for bitumen above the approximate respective softening points.
  • Stir it thoroughly until it is homogeneous and free from aft bubbles and water.
  • Pour the melt into the container to a depth of at least 10 mm in excess of the expected penetration.
  • Protect the sample from dust and allow it to cool in the atmosphere at a temperature between 15 to 30°C for 11/2 to 2 hours for 45 mm deep container and 1 to 1 1/2 hours for 35 mm deep container.
  • Unless otherwise specified carry out testing at a temperature of 25 ± 0.1°C.
  • Place it along with the transfer dish in the water bath at 25 ± 0.1°C and allow it remain for 11/2 to  2 hours for 45 mm deep container and 1 to 11/2 hours for 35 mm deep container.
  • Fill the transfer dish with water from the water bath to a depth sufficient to cover the mould completely.
  • Remove the transfer dish along with the mould from the water bath after a specified period of time and put it upon the stand of penetration apparatus.
  • Adjust the needle (previously washed, cleaned well with benzene and dried) just to make contact with the surface of the sample.
  • The sum of the weights of the needle, carrier and superimposed weights i.e. the total moving weight shall be 100 ± 0.2s grams.
  • Bring the pointer to zero.
  • Release the needle for five seconds and measure the distance penetrated.
  • Make at least three determinations at points on the surface of the sample not less than 10 mm apart and not less than 10 mm from the side of the dish.
  • After each test, return the sample and transfer dish to the water bath and wash the needle with benzene and thy.
  • In case of the material of penetration greater than 225 make three determinations on each of two identical test specimens using a separate needle for each determination, leaving the needle in the sample on completion of each determination to avoid disturbance of the specimen.  


  • Express the depth of penetration of the needle in tenths of mm.
  • The value of penetration reported shall be the mean of not less than three determinations whose values do not differ by more than the difference given below
Penetration Maximum difference
0 to 49 2
50 to 149 4
150 to 249 6
250 and above 8


The duplicate results should not differ by more than the following

Penetration Repeatability Reproducibility
Below 50 l Unit 4 Units
Above 50 3% of their mean 8% of their mean


  • If the sample contains extraneous matter, it should be sieved through I.S. Sieve 30 (IS; 460-1962).
  • To avoid overheating at the bottom of the container, use of an air oven or sand bath is recommended.
  • While the needle is penetrating into the sample, if there is any movement of the container, that determination shall be discarded. 


Description Units Test I    Test 2 Test 3
Pouring temperature °C
Period of Cooling in the atmosphere Minutes
Room temperature °C
Period of cooling in the water bath Minutes
Actual test temperature °C
Penetrometer reading (Initial) I / 10th  mm
Penetrometer reading (Final) I / 10th  mm
Penetration I / 10th  mm
Average Penetration I / 10th  mm
Repeatability %

Penetration Test of Bitumen – Excel Performa

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