Bitumen tests
:Some tests are carried out on the bitumen samples among which the
following tests could be mentioned
1. Penetration grade test
Bitumen stiffness is generally determined using the
penetration test. The test is carried out on a sample which is placed under a
needle. The needle is loaded with a 100 g weight. The penetration of the needle
into the bitumen sample after 5 seconds is measured in units of 0.1 mm which is
called the penetration grade. The bitumen temperature in this test should be 25
ºC. The low penetration value means that the bitumen is stiffer.
:To read more, study the following article
2. Viscosity test
The bitumen viscosity value has an
important effect on the determination of bitumen properties so that the higher
viscosity value shows the higher solidity of the bitumen. It is obvious that
the rise in temperature leads to the reduction of viscosity. This test is done
using the Saybolt Furol apparatus or according to the kinematic method.
3. Flash point test
According to the definition, the flash point is the
temperature at which the gases resulted from bitumen heating ignite when a
flame is brought into contact with them. Knowing this temperature is important
to determine the maximum temperature that bitumen could be heated which should
be less than the flash point.
4. The Thin Film Oven Test:
Oils and other compositions existing in the bitumen are separated from it at high temperatures and this leads to the
reduction of bitumen weight which is called weight loss. Weight loss is one of
the important properties of bitumen. According to the test method, the
temperature and time of the experiment should be 163 ºC and 5 hours
respectively which approximate the construction conditions of hot mix bitumen.
5.
Ductility test
If a bitumen sample with a 1 cm2 area is
stretched at the rate of 5 cm/minute, the length of the sample before breaking
is named the ductility of the bitumen.
To read more study the following article:
6. Solubility test
If a bitumen sample is dissolved in trichloroethylene or
carbon disulfide, an amount of impurity remains in the solution which could be
measured to determine the purity of bitumen. In fact, if the impurity weight is
subtracted from the whole weight of the bitumen and is divided into it, the
result indicates the purity of bitumen.
7. Softening point
The
softening point is the temperature at which the bitumen transforms from solid
to liquid or starts flowing. In fact, the higher softening point shows the less
sensitivity of the bitumen against the temperature change. The softening point
of bitumen is generally 60 to 70.