Question

Bitumen of grade 80/100 means:

1. its penetration value is 8 mm
2. its penetration value is 10 mm
3. its penetration value is 8 to 10 mm
4. its penetration value is 8 to 10 cm

Answer 1

Correct Answer - Option 3 : its penetration value is 8 to 10 mm

Explanation:

• Bitumen is classified on the basis of either its penetration value or its viscosity.
• The grade of bitumen is decided on the basis of the penetration test.

Penetration test:

• The hardness of bitumen is obtained by the penetration test.
• It measures the distance a standard blunt pointed needle will vertically penetrate a sample of material at 25°C, the load being 100 gram and time of application of load being 5 seconds.
• The unit of penetration is 1/10 mm. Thus 80/10 grade bitumen means 8 - 10 mm penetration.
• 30/40 and 80/100 grade bitumen are more commonly used, depending upon bitumen construction type and climate conditions.
• In hot climate, a lower penetration grade bitumen like 30/40 bitumen is preferred.