Tests to determine the density of bitumen
There are several ways to determine the specific gravity of asphalt on all these methods, is Archimedes law. By definition, the specific gravity of bitumen, the tar-to-weight ratio of a certain volume of water volume at a given temperature. Among the methods available for determining the density of asphalt is:
Method nickel plant
Pycnometer method
Knowing the density of bitumen is important for two reasons:
Because of the amount of bitumen in the asphalt know where the talk comes, it will be expressed in weight percent, if the pitch is actually the volume to be measured, so it is necessary to know the relationship between weight and volume of bitumen . And since bitumen are generally warm, so knowing the coefficient of thermal expansion of bitumen is also required to be able to calculate the density of bitumen in any temperature. Otherwise density bitumen should be required to identify and measure the temperature.
Is a useful tool to determine the source of bitumen for asphalt weight. For example, a specific gravity of about 1.0 and a specific gravity of oil tar tar tar depending on the recipe varies between 1.10 to 1.25. The specific weight of 15.6 or 20 degrees Celsius at a given temperature are determined.
A complete description of the specific gravity test bitumen standards are detailed below:
For oil bitumen Standard Methods, IP. 59/57 method F
For bitumen tar Standard Methods, G.IP. -57, Method A
ASTM Methods, D: 70-52
All standards are listed in the pycnometer to measure the density of asphalt used.
As you know, the pitch is a function of temperature, so it is necessary to determine the pitch parameters allow the temperature constant. But if the experiment at different temperatures can be used the following approximate relationship:
V = [1 + c (t-15.6)] V15.6
where in :
V: volume of bitumen at temperature t.
c: coefficient of thermal shrinkage of less than 0.966 times the density tar to tar and bitumen with higher density of 0.966 0.00072 0.00063 is equal.
V15.6: The volume of bitumen at a temperature of 15.6 degrees Celsius.
Testing method
The empty pycnometer dry and we weighed (W1), the empty pycnometer full of water with a temperature of 25 ° C, and we weigh it (Ww). Water pycnometer empty and then thoroughly dry them. Then the pitch (about 60 grams) inside the shed and set it to put weight (W2). Next, fill the pycnometer with distilled water to the mark and it's weight (W3); note that at this stage the bitumen is available pycnometer.
Another interesting point is that when a liquid or molten bitumen used in testing, we should keep the same pitch for a long time until all the air bubbles out of it. This test can be done with tar semi-solid or solid.
Given the density of asphalt will be calculated as follows:
