The Bureau of Indian Standards classifies bitumen into grades 65/25, 85/40 etc. The first and the second numbers respectively refer to
- ASoftening point and penetrationCorrect
- BPenetration and softening point
- CFlash point and penetration
- DFlash point and softening point
Solution
Concept
BIS Bitumen Grading
Formula
No formula
Step-by-step solution
- In BIS classification (e.g., 65/25), the first number indicates the softening point in °C - The second number indicates the penetration value in tenths of a millimeter - Therefore, the first and second numbers refer to Softening point and Penetration respectively
Explanation
In the Bureau of Indian Standards classification system for bitumen grades (such as 65/25 or 85/40), the first number indicates the softening point in degrees Celsius, while the second number represents the penetration value in tenths of a millimeter.
Shortcut
Remember SP (Softening Point, Penetration) in alphabetical order: S comes before P, so the first number is Softening point and the second is Penetration.
Common mistake
Many students mistakenly choose Option B (Penetration and softening point) because penetration grade notation (e.g., 80/100) is more common and lists penetration first, leading them to confuse the order of softening point and penetration values.
Correct answer: A) Softening point and penetration