Penetration test - Test on bitumen.

Crude petroleum obtained from different source contains different portion of different constituents. 

Hence, it's properties may differ. 

Therefore, to judge their suitability as binders following tests are required. :- 

1) Penetration test. *

2) Ductility test.* 

3) Softening test.* 

4) Viscosity test.* 

5) Float test. 

6) Specifically gravity test. 

7) Flash and fire point test. 

8) Spot test. 

9) Loss on heating test. 

10) Water content test. 

1) penetration test ( viscosity test on bitumen) 

An indirect measure of viscosity is tie the amount of penetration of a standard needle under standard  conditions, of load time and temperature. 

The test measure the hardness or softness of bitumen  in terms of 10mm of the standard needle. 

   

           Fig. Penetrometer apparatus

Standard conditions for penetration test:-

a) Temperature :-

25° ( test to be performed after sample is kept for one hour in water bath at this temperature) 

b) Load on needle :- 100 gm . 

c) Time in which penetration recorded :-

           - 5 second. 

Test procedures :- 

The bitumen is softened to a pouring consistency, stirred well and poured into the test contains. 

The depth of bitumen in container is kept at least 15 mm more than the expected penetration ( IS 1203-1958) 

1) Now, the sample container are placed in a temperature controlled water bath at a temperature of 25°  for one hour 

2) At the end of one hour, the sample is taken out of water bath and needle is brought in contact with the surface of bitumen sample and the reading of dial is set at zero or the reading of dial is noted, when the needle is in contact with the surface of the sample. 

3) Now, the needle is released and the needle is allowed to penetrate for 5 second and the final reading is recorded. 

- On the same sample, at least three penetration observation should be taken at distance at least 10 mm apart. 

After each test  , the needle is disengaged, wiped, with benzene and dried. 

The amount of penetration is shown in fig. 

4) The mean value of three measurement

Is reported as penetration test. 

5) The accuracy of the test depends upon pouring temperature , size of needle, weight placed on needle, and test temperature. 

6) The grade of specimen is specified in terms of penetration value. 

30/40 grade bitumen indicates the penetration value of the bitumen in the range of 30 to 40 at standard test conditions. 

Penetration test is applied exclusively to bitumen. Tars being soft, penetration test on these materials can't be carried out . 

Note :- penetration value of different types of bitumen used in road construction range between 20  to 25.

However, 30/40 and 80/100 grade bitumen are more common for road construction. 

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