This test method covers the determination of the theoretical maximum specific gravity and density of uncompacted bituminous paving mixtures at 25°C.
Summary of Test Method
A weighed sample of oven-dry bituminous mixture in a loose condition (A) is placed in a tared vacuum vessel (pycnometer). Water is added to completely submerge the specimen. Vacuum is then applied to thoroughly remove air within the specimen. The vacuum is then removed and the volume of the sample is determined by completely filling the pycnometer full of water and weighing in air.
Significance and Use
The theoretical maximum specific gravity is used to calculate the void ******* in compacted mixtures. It also provides a target value for compaction of paving mixtures.
Apparatus
Pycnometer
Vacuum pump
Balance
Water bath
Thermometer
Materials
Loose bituminous paving mixture. The size of the sample shall conform to the following.
50 (2)Aggregate Maximum Size, mm (in
6000 Minimum Sample Size, g
-------------------------
37.5 (1-1/2)Aggregate Maximum Size, mm (in
4000 Minimum Sample Size, g
------------------------------
25 (1)Aggregate Maximum Size, mm (in
2500 Minimum Sample Size, g
------------------------------
19 (3/4)Aggregate Maximum Size, mm (in
2000 Minimum Sample Size, g
------------------------------
12.5 (1/2)Aggregate Maximum Size, mm (in
1500 Minimum Sample Size, g
---------------------------------
9.5 (3/8)Aggregate Maximum Size, mm (in
1000 Minimum Sample Size, g
------------------------------------
4.75 (#4)Aggregate Maximum Size, mm (in
500 Minimum Sample Size, g
Procedure
1) Calibrate the pycnometer by filling it with water at 25°C and determining the mass of the pycnometer plus water. Designate this mass as D .
2) Separate the particles of the sample by hand, taking care to avoid fracturing the aggregate, so that the particle of the fine aggregate portion are not larger than 6.3 mm (1/4 in.).
3) Oven dry the sample to constant mass at a temperature of 105°C.
4) Cool the sample to room temperature. Place the required sample size (mass) in the tared pycnometer. Determined the mass of the sample and designate this mass as A . Add sufficient water at 25°C to completely cover the sample.
5) Remove the air trapped within the sample by applying vacuum for period of 5 to 15 minutes. Agitate the container and *******s during this vacuum period continuous vigorous shaking at intervals of about 2 minutes.
6) At the end of the vacuum period, gently release the vacuum.
7) Fill the pycnometer with water and adjust the *******s (water plus sample) to a temperature of 25°C. Determine the total mass of the pycnometer plus *******s and designate this mass as E .
8) Calculate the maximum theoretical specific gravity of the bituminous mixture, at 25°, as follows:
Gmm = A/(A+D-E)
08-07-2008, 05:50 PM
الكثافة القصوى للخلطة المفككة
