Blowed bitumen is obtained by blowing hot air into pure bitumen in the final stage of purification. In this process, hot air at a temperature of 200 to 300 ° C is blown into the bitumen chamber by perforated pipes. As a result of this process, the hydrogen atoms present in the hydrocarbon molecules of the bitumen combine with the oxygen in the air, and by the formation of water, the polymerization takes place. Blowed bitumen has a lower degree of penetration than pure bitumen, has a higher degree of softness and is less sensitive to temperature changes. Therefore, bitumen grade 6525 price trends in 2020 are traded at different prices in the market due to currency price fluctuations.
What is bitumen grade 6525?
Bitumen penetration test is used to determine the relative hardness of blown bitumen and pure bitumen. One of the applications of degree of penetration is in naming pure bitumen and blown bitumen. Pure bitumens are named only on this basis, but the criterion for naming blown bitumens, in addition to the degree of bitumen penetration, is also the degree of softness of the bitumen. For example, 40-50, 60-70, 85-100 and% bitumens are among the common pure bitumens in road construction.
The two numbers that come with pure bitumen indicate that the degree of bitumen penetration is in this range. Bitumens R85 / 25, R90 / 15, R110 / 10 and… are examples of common blown bitumens in Iran, the first number indicates the degree of penetration of bitumen and the second number indicates the soft point of bitumen.
By definition, the degree of penetration of bitumen is the longitudinal value (in millimeters) that a standard needle with a certain shape penetrates the bitumen at a temperature of 25 degrees Celsius for 5 seconds under a load of 100 grams.
One of the applications of the results of this experiment is that the hotter the climate of the area where the bitumen is to be used, or the higher the traffic and the heavier the load of vehicles, the more penetrating the bitumen should be. And vice versa, the colder the climate of the area, the less penetration bitumen should be used.
Therefore, the harder the bitumen, the lower the degree of penetration and the higher the degree of penetration of the bitumen, the softer the bitumen. Bitumens with a penetration degree of about 80 are used in asphalts such as asphalt concrete and bitumens with a higher degree of penetration in macadam bitumen and cold asphalt.
This test is described in detail in the following standards:
Standard Methods, IP. 49/58
ASTM Methods, D: 5-52
If we test the degree of penetration at a temperature equal to the softening point of bitumen, a penetration degree of 800 is obtained for all bitumens, so a parameter called the degree of penetration is defined, which indicates the sensitivity of bitumen to temperature changes. The lower the degree of penetration, the more sensitive the bitumen to temperature changes. For road bitumens, the degree of penetration varies from 2- to +2. This mark is less than -2 for tar bitumen and +2 for blown bitumen.
The purpose of the experiment
The purpose of bitumen penetration test is to determine the relative hardness of pure and blown bitumen, which is used to name these bitumens.
Test equipment
• Special device for degree of penetration
• Thermometer
• Knife
• Hot water bath
• Two small containers of different sizes
• Stopwatch
According to the cases mentioned, bitumen demand in Iran and the Middle East has increased a lot.
Bitumen grade 6525 price trends on the market
The largest bitumen suppliers use solid or semi-solid bitumen for their experiments, so it must be heated to 176 ° C to melt. Then pour the molten bitumen into the container for the test machine; Until it is full. The air trapped in the bitumen should be removed and the bitumen surface should be smoothed with a spatula. Now give the bitumen a chance to cool.
Now place the cooled bitumen container on the test machine and place the thermometer on the holder base; So that the lower part of the thermometer does not hit the bottom of the container.
First, we obtain the approximate degree of ignition of the bitumen so that we can use the result in the main test. At this stage, regardless of the heating rate at a constant speed of about 12 degrees Celsius per minute, we heat the bitumen and by passing a flame over the bitumen at a temperature above 250 degrees Celsius, the temperature in return creates a spark on the surface of the bitumen. Be considered as the estimated degree of ignition. Now Bitumen grade 6525 price trends on the market have faced price changes due to changes in currency fluctuations.
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