Penetration Test on Bitumen (Ref - IS:1203)

[Srinivasan]

Penetration Test on Bitumen (Ref - IS:1203)


OBJECTIVE:
To determine the Penetration value of the Bitumen.
To determine the suitability of bitumen for its use under different climatic condition and type of construction

APPARATUS/EQUIPMENTS REQUIRED:

- Container: a flat bottomed cylindrical metallic dish
For penetration below 225
Diameter in mm = 55
Internal depth in mm = 35

For penetration above 225
Diameter in mm = 70
Internal depth in mm = 45

- Water bath: maintained at 25±0.1°C
- Penetrometer as shown in figure
- Transfer dish or tray
- Therometer, Range 0-45 Deg C
- Needle: A straight, highly polished, cylindrical hard steel, as per following dimension

THEORY:
This test is applied almost exclusive bitumen. For tars, cutback and emulsions other consistency are used. This test determines the hardness or softness of bitumen by measuring the depth in millimeter to which a standard loaded needle will penetrate vertically in 5 seconds while the temperature of the bitumen sample is maintained at 25°C.
This test is widely used world over for classifying the bitumen into different grades. 80/100 bitumen denotes that the penetration value ranges between 80 and 100.

PROCEDURE:

1. The bitumen is softening to a pouring consistency at a temperature not more than 60°C for tars and 90°C for bitumen and Stir it thoroughly to remove air bubbles and water.
2. Pour it into a container to a depth of at least 15mm in excess of the expected penetration.
3. Cool it at an atmospheric temperature of 15 to 30°C for 1 to 1.5 hours for 35 mm depth container and 1.5 to 2 hrs for 45 mm deep container. Then place it in a transfer dish in the water bath at 25.0 + 0.1°C and allow it to remain for 1 to 1.5 hours for 35 mm deep container and 1.5 to 2 hrs for 45 mm deep container.
4. 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 noted, when the needle is in contact with the surface of the sample.
5. Now the needle is released and allowed to penetrate for 5 seconds and the final reading is recorded on the same sample at least three penetration observations should be taken at distances at least 10 mm apart. After each test, the sample needle is disengaged, wiped wit benzene or petrol and dried.
6. The mean value of three measurements is reported as penetration test.
7. The accuracy of the test depends upon pouring temperature, size of needle, weight placed on needle, and test temperature.

Detailed procedure is attached below.