Bitumen of grade 80/100 means

Question

Question

This question was previously asked in

BPSC AE Paper 6 (Civil) 11 Nov 2022 Official Paper

Answer 1

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,s and the time of application of load being 5 seconds.
The unit of penetration is 1/10 mm. Thus 80/100 grade bitumen means 80 and 100 give the idea of the penetration value of the bitumen and its value is equal to 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 climates, a lower penetration grade bitumen like 30/40 bitumen is preferred.