To evaluate consistency, viscosity, temperature susceptibility, gradation, and safety of bitumen, different types of tests are conducted. There are various tests to evaluate the characteristics of bituminous rocks with bitumen testing equipment. Some of the tests that are normally administered to evaluate various characteristics of bituminous rocks are given below:
Ductility is the characteristic of bitumen that allows it to undergo deformation. Ductility is described as the measure in cm, and the standard sample of the bitumen will be deformed without breaking. The bitumen sample is heated and poured into the moulds. Then the sample in the moulds is cooled in the air. After that, they are cooled in the water bath. The excess bitumen is removed, and then the surface is smoothened with the help of a hot knife. Then the moulds are kept in the water bath of the bitumen extraction machine. The moulds’ sides are cut, the clips are secured on the machine for operating it. The value of ductility is influenced by pouring and test temperature, rate of pulling, etc.
Softening point test
Softening point is the point of temperature at which bitumen achieves a specified degree of softening under the defined test conditions. This test is carried out using the Ring and Ball apparatus. The brass ring carrying the bitumen sample for test is kept in glycerine or water-like liquid at a specified temperature. A ball made of steel is put on the sample and, the liquid is heated. Temperature is recorded when the softened bitumen reaches the metal plate that is kept below.
Viscosity indicates the liquid characteristic of bituminous. It measures the resistance to flow. This property highly affects the strength of the resulting concrete mixes at the temperature of application. At the time of mixing, viscosity is observed to get lower stability values in the resulting mixture.
Flash and Fire Point Test
According to the grades of bitumen, volatile is released by materials at a high temperature. These volatiles are dangerous as they can catch fire. Hence, the temperature must suit every grade of bitumen. Flash Point is the temperature specified by BIS at which the bitumen vapour immediately catches fire in the form of ash under the given condition of the test.
This test is conducted to measure the hardness or softness of bitumen by evaluating its depth. Standardized penetration tests of bitumen apparatus and procedure are used as per the BIS. The penetrometer made-up of a needle assembly that weights 100g and a tool for releasing and locking in any position. The bitumen that is decreased to a pouring consistency is stirred and emptied into containers above the expected penetration. This test is conducted at a temperature of 250C. Penetration value is affected by any error in pouring and test temperature, needle’s size, and weight placed on the needle.
Various other tests can also be used to check the quality of bitumen like the float test, water content test, specific gravity test, etc.