Bitumen is a dense, high viscosity hydrocarbon derived from petroleum, the first type is natural bitumen, but sometimes it can be toxic bitumen found under oil hills and lakes, and the other type is bitumen refined from crude oil deposits. Bitumen contains 2% oxygen, 11% hydrogen, and 87% carbon.
This product is a high molecular weight hydrocarbon containing oil, resin and asphaltene. The presence of 5 to 30% asphalt in the bitumen makes the bitumen harden. Bitumen is produced in two ways:
Bitumen and bitumen fumes, they are mainly used in construction, road construction, road insulation, street asphalt or roof insulation. According to different production processes, this product is classified for example different types and grades and physical tests such as penetration test, elasticity test, viscosity test, point test, combustion, melting test, softening point test, etc.
It should be noted that some of these categories are based on the results of tests conducted on bitumen and others are based on the type of purification and steps that are performed on bitumen.
Other bitumen fractions, including oxidizer, reducing agent and emulsifier, have also been classified based on production stages and the type of crude oil refining.
However, bitumen must be thoroughly tested to determine its level of toxicity and to determine if bitumen is dangerous. Several tests are carried out on it, which are as follows:
Bitumen quality tests include elasticity tests, spot tests, dissolution tests, viscosity tests, softening point tests, flash point tests, permeability tests, rock specific sensitivity tests, and determination of bitumen heating losses.
In this bitumen test, a certain amount of bitumen is completely dissolved in a suitable solvent. If the bitumen is not properly dissolved, this process is repeated from the beginning. In the next step, the solution is kept for 30 minutes in a place with a temperature of 30 degrees. Technicians then filter some of the solution onto filter paper and wait. Once the stain dries, technicians see the stain. If the color and shape of the spot are uniform, the test result will be negative.
Otherwise, the test result will likely come out positive. A negative test result means that there are no additives in the bitumen tested and it is considered pure. On the contrary, a positive result indicates that the tested bitumen contains some additives. For example, the stain test on Iraqi bitumen is positive because it contains large amounts of sulfur.
The flexibility of bitumen means the ability of bitumen to change its shape under heavy loads without cracking. The bitumen elasticity test is carried out at a distance where a standard bitumen mold with a cross section of 1 x 1 cm is pressed. To test the flexibility, the bitumen sample must be heated and poured into the mold.
Then the excess bitumen must be cut off with a hot knife. After cooling, the mold is placed in a water tank at 27°C for at least 90 minutes. After the sides of the mold are separated, clamps are attached to it and the tensioning machine pulls it using a standard motor at a speed of 5 cm/min.
The solubility of bitumen in carbon disulfide, naphtha-88 and carbon tetrachloride is of great importance in construction. Lack of solubility is a sign of the presence of metal in the bitumen. Therefore, the amount of bitumen is measured using its solubility in carbon disulfide.
For the test, a small sample of bitumen is dissolved in 100 ml of carbon disulfide and the solution is passed through a sieve. After drying, the material remains. The tailings are weighed and used to calculate the bitumen content.
The purpose of the viscosity tester is to determine the desired viscosity of bitumen. First, experts heat the sample up to 60 ° C for wire and pits and 90 ° C for bitumen. They heat the sample until it liquefies completely. Then about 20 ml of it is poured into a small beaker and kept at a temperature of 135 ° C. At this point, experts fill the viscometer and set it at 135 ° C for ten minutes. Then the filled viscometer is placed vertically into the water tank. Then specialists create a vacuum and connect it to the viscometer with a valve. After the viscometer remains in the water tank for 30 minutes, the valve is opened and the asphalt flows into the viscometer. The next step is to remove the viscometer from the water tank and place it in an oven at 135°C until it is completely removed from the viscometer. Finally, highly viscous bitumen results in insufficient and inconsistent coverage. Similarly, very low viscosity leads to poor coating because bitumen tends to flow. Therefore, the viscosity at 135 ° C is very important in the quality of the bonding of bitumen to the material. One of the most well-known methods for determining the viscosity of bitumen is the result of this test. The result of this test is obtained as numbers from 10 to 40, and it is good to know that the lower the number obtained in this test, the lower the viscosity of the sample and the higher the number, the higher the viscosity. a sample. This will be more than just an experience.
Bitumen softening point is the temperature at which bitumen softens. The purpose of this test is to determine the temperature at which a standard ball passes through the pitch ring of a copper ring. A copper ring containing a sample of bitumen at room temperature suspended in water or glycerol. This material is heated at a rate of 5 degrees per minute. The temperature at which dilute bitumen contacts the bottom of a metal plate a short distance below the ring is called the softening point of bitumen.
The bitumen flash point test indicates the temperature at which bitumen releases fumes for a few seconds after being exposed to fire. This test is vital and very important in determining the quality of bitumen, because toxic fumes are released if bitumen not suitable for the area is used. It will have dire consequences. For example, if some bitumen with a low flash point is used in a hot tropical region, the bitumen will likely ignite and release hazardous gases. To perform this test, experts place a small flame near the molten bitumen and record the temperature at which the bitumen releases steam. Then continue heating until you find the "flash point".
Source: Nikan west Gilsonite company
