All of you are aware that the bitumen is a by-product material of petroleum which is mainly used for road construction work & other miscellaneous work.
We are going to discuss the test, which is useful to grade the bitumen-based on its consistency.
Bitumen penetrated in a semi-solid state at the temperature of 25°C by a steel needle carrying 100gm load for 5 seconds to measure the consistency & hardness of the bitumen is known as a penetration test of bitumen.
The value of penetration is measured in 1/10 mm.
The different grades of bitumen have been listed below & the measured penetration value can be correlated to those values.
Bitumen Grade | Penetration Value |
S-35 | 30 to 40 |
S-45 | 40 to 50 |
S-55 | 50 to 60 |
S-65 | 60 to 70 |
S-90 | 80 to 100 |
S-200 | 175 to 225 |
The grade 80/100 represents the penetration value of bitumen that lies between 80 to 100, which is arrived from the penetration test. The grade 80/100 mostly used in India because of hot weather conditions.
Lower Penetration is preferred in hot climatic conditions so that it doesn’t get soft due to the heat. On the other hand, higher penetration value is preferred in cold conditions to avoid brittleness.
The penetration test of bitumen has been conducted as per IS code 1203.
The sample bitumen has to be melted at 90°C which must be in uniformity & without bubbles. Ensure the specimen does it free from moisture & dust.
The Penetration value = G2- G1
A minimum of 3 tests has to be done for the same sample at different points. Each test point should be conducted at 10mm away from the previous test point. It should also be 10mm inside of the container, as shown in the below picture.
Penetration reading | Point 1 | Point 2 | Point 3 |
Initial reading G1 | |||
Final Reading G2 | |||
Average Penetration value |
The average value of the 3 test points is the Penetration value of the bitumen. The penetrate value difference between those test points should be in the limit as given below.
Penetration | Difference |
0 to 49 | 2 |
50 to 149 | 4 |
150 to 249 | 6 |
250 and above | 8 |
Video Courtesy – NCTEL
Happy Learning 🙂
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