Bitumen is a dense, highly viscous, oil-derived hydrocarbon, The first type of it is natural bitumen but sometimes it can be toxic bitumen, which is found under oil hills and lakes, and the other type is refined bitumen from crude oil sedimentation. Bitumen contains 2% oxygen, 11% hydrogen, and 87% carbon.
This product is a high molecular weight hydrocarbon containing oils, resins, and asphaltene. The presence of 5 to 30% asphaltene in bitumen causes the bitumen to be hardened. Bitumen is produced in two ways:
- Direct execution
- Blowing air, which is done based on a cross-sectional or continuous process
Bitumen and bitumen fumes are mainly used in construction, road construction, road insulation, asphalting of streets, or roof insulation. According to different production processes, this product is classified for instance different types and grades and physical tests such as penetration test, flexibility test, viscosity test, point test, Ignition, solubility test, softening point test and others.
It should be noted that some of these classifications are based on the results of tests performed on bitumen and others are based on the type of refining and steps performed on bitumen.
Other parts of bitumen, including oxidized, cutback, and emulsion, were also classified based on production steps and type of crude oil refining.
Bitumen Quality Tests
Bitumen, however, must be tested precisely to determine the level of its toxicity and recognize the dangerous bitumen. There are several tests that are done on them which are as follows:
Bitumen quality tests include flexibility tests, spot tests, solubility tests, viscosity tests, softening point tests, flash points tests, permeability tests, special stone sensitivity tests, and determination of bitumen losses in heating.
Bitumen Spot Test
In this test, a certain amount of bitumen is completely dissolved in a suitable solvent. If the bitumen is not dissolved properly, this process is repeated from the beginning. In the next step, the solution is kept in a place with a temperature of 30 degrees for 30 minutes. The technicians then filter some of the solutions onto a filter paper shed and wait. When the stain dries, technicians observe the stain. If the stain is uniform in color and shape, the test result will be negative.
If not, a positive test result will probably appear. A negative test result means that there is no additive in the tested bitumen and it is considered pure. In contrast, a positive result indicates that the tested bitumen contains some additives. For example, the Spot test on Iraqi bitumen is positive because it contains large amounts of sulfur.
Bitumen Flexibility Test
Bitumen flexibility means the ability of bitumen to deform under heavy loads without cracking. The bitumen flexibility test is performed at a distance that which a standard bitumen mold with a cross-sectional area of 1 in 1 cm is pressed. To test the flexibility, the bitumen sample should be heated and poured into a mold.
Extra bitumen should then be cut with a hot knife. After cooling, the mold is placed in a water tank at 27 ° C for at least 90 minutes. After separating the sides of the mold, the clamps are hooked to it and the traction device pulls it using a standard motor at a speed of 5 cm per minute.
Bitumen solubility test
The solubility of bitumen in carbon disulfide, naphtha 88, and carbon tetrachloride is of great importance in constructions. Insolubility is a sign of the presence of a mineral in 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 filter. After drying the material remains. The residue is weighed and used to calculate the bitumen content.
Read more: Is Bitumen Harmful to Humans
Bitumen Viscosity Test
The purpose of the viscosity test is to determine the desired viscosity or viscosity of the bitumen. First, the specialists heat the sample to 60 degrees Celsius for the wires and pits and 90 degrees Celsius for the bitumen. They heat the sample until it completely melt into liquid. Then about 20 ml of it pours a small glass and keeps it at 135 degrees Celsius. At this stage, the specialists fill the viscometer and place it at 135 ° C for ten minutes. The filled viscometer is then placed vertically in the water tank. Specialists then create a vacuum space 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 is allowed to flow into the viscometer. The next step is to remove the viscometer from the water tank and place it in the oven at 135 ° C until it is completely out of the viscometer. Eventually, bitumen that is too viscous will lead to insufficient and inconsistent coverage. Similarly, very low viscosity leads to poor coverage because the bitumen tends to flow. Therefore, viscosity at 135 ° C is very important in the quality of bitumen bonding with materials. One of the best-known methods for determining the viscosity of bitumen is the result of this test. The result of this experiment is obtained in the form of numbers 10 to 40. It is good to know that the lower the number obtained in this experiment, the lower the viscosity of the sample and the higher the number, the higher the viscosity of the sample. It will be more of an experiment.
For example, bitumen with a viscosity of 10 or more are suitable for repairs, sidewalks, and road construction. AC bitumen is another subset that are named and divided based on viscosity testing. AC bitumen are mostly used in the United States. AC 30 bitumen is similar to VG 30 bitumen, except that VG 30 bitumen has a stronger market in India.
Bitumen Softening Point Test
Bitumen softening point is the temperature at which bitumen softens. The bitumen softening point test is also known as the ring and ball test. The purpose of this test is to determine the temperature at which a standard ball passes through a bitumen ring in a brass ring. A brass ring containing a bitumen sample at room temperature suspended in water or glycerin. Then a steel ball is placed on the bitumen disk. The material is heated at a rate of 5 degrees per minute. The temperature at which the softened bitumen touches the bottom of a metal plate a short distance below the ring is referred to as the softening point of the bitumen.
Flash Point Test
The bitumen flash point test shows the temperature at which bitumen releases vapors for a few seconds upon exposure to fire. This test is vital and very important in determining the quality of bitumen, because if improper bitumen is used for an area, the release of toxic vapors. It will have dangerous consequences. For example, if some bitumen with a low flash point is used in a hot, tropical region, the bitumen will probably ignite and release dangerous gases. To perform this experiment, specialists place a small flame close to the melted bitumen and record the temperature at which the bitumen releases steam. Then continue heating to find the “flash point”.
According to the tests done and results and the primary materials that they have been made by, what we can say about toxic bitumen is that they are not usually highly toxic but the long-term exposure to bitumen can result in lung and stomach cancer, skin pigment changes, bronchitis, and emphysema. Furthermore, bitumen additives might harm the liver, kidneys, and neurological system. Suffocation and possibly death can occur when hot bitumen leaks hydrogen sulfide gas into the air.