Monday, September 7, 2020

Penetration Test of Bitumen

Determine the penetration test of bitumen


Penetration test Icon Image

Penetration value is the physical process, measurement of hardness or consistency of bituminous material. The penetration values is calculated by the vertical distance traversed or penetrated by the point of a standard needle in to the bitumine sample under standard conditions of load, time and temperature. This amount of penetration is measured in one tenth division of a millimeter. The Penetration test may not as suitable for use in connection with the testing of road tar because of the high surface tension exhibited by these materials.

The consistency of bituminous material and assess its suitability for its use under different climatic conditions and types of construction.


  • Penetration apparatus, 
  • Thermometer, 
  • Time measuring device, 
  • Transfer dish, 
  • Water bath, 
  • Needle, 
  • Container.


  1. Soften the material to a pouring consistency at a temperature not more than 60 ̊ C for tars and 90̊ C for bitumen above the approximate softening point and stir it thoroughly until it is homogenous and is free from air bubbles and water. Fill the container to a depth at least 10mm with the melt bitumen in excess of the expected penetration. Protect the sample from dust and allow it to cool in an atmosphere at a temperature between 15̊ to 30̊ C for one hour. Then place it along with the transfer dish in the water bath at 25.0̊ ± 0.1̊ C and allow it to remain for 1 to 1.5 hour. The test is carried out at 25.0̊ ± 0.1̊ C, unless otherwise stated. 
  2. Extract the dish from the water bath to depth sufficient to cover the container completely. Place the sample to the  penetration apparatus. 
  3. Safely Clean the needle with benzene, dry it and load with weight. Recommended loading assembly required is 100 ± 0.25gms, including the weight of the needle, carrier and super-imposed weights. 
  4. Adjust the needle carefully to make contact with the surface of the sample. This can be done by placing the needle point with its image reflected by the surface of the bituminous material. 
  5. Make sure the pointer of the dial to read zero or note the initial dial reading.
  6. Carefully Release the needle for exactly five seconds. And note down the reading of needle.
  7. Take at least 3 consecutive reading at points on the surface to conduct of Penetration test of the sample of  10 mm apart the side of the dish. After each test the needle clean with benzene and dry.


The Penetration value of bitumen sample is ________________ .


1. Wear face shields, safety glass and heat resistant gloves with close-fitting cuffs.

2. The test should avoid in the presence of any ignition sources in close proximity of test set-up.

3. Before each penetration process, the needle should be cleaned with benzene.

4. The Penetration test procedure should be maintain to all specified level during test conducted. 

Information Civil

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