Concept: The various tests performed on bitumen are as follows:
Test
Characteristics
Penetration test
It is performed to determine the grade of bitumen. Penetration value also gives the idea about the softness and harness of the bitumen Higher the grade of bitumen, softer will be the bitumen.
Plate bearing test
It is done on soil subgrade and it determines the modulus of subgrade reaction. Modulus of subgrade reaction is given by k=
p
Δ
=
p
0.125‌cm
‌kg∕cm3 Where, p = pressure corresponding to settlement of 0.125 cm.
CBR test
CBR value can be defined as the ration of load at penetration of 2.5 mm or 5.0 mm to the standard load (i.e. 1370 kg for 2.5 mm & 2055 kg for 5.0 mm) for same penetration. CBR=
This test is used for determine the thickness of the pavement or subgrade. Greater the CBR value, lower will be the thickness.
Abrasion test
It is performed to determine the hardness of the aggregates used in the pavement. It is performed by Los Angeles, Devel and Dorry Abrasion value AV=
W2
W1
×100 W2=weight‌of‌aggregates‌passing‌through‌1.70‌mm‌sieve‌andW1=initial‌weight‌of‌aggregates. Note:- Abrasion Value should not be greater than 30% for surface and 35% for bituminous concrete.