ASTM D71 Standard Test Method for Relative Density of Solid Pitch and Asphalt (Displacement Method)
9. Procedure
9.1 Tare the balance with a piece of 0.127-mm (5-mL) Nichrome wire or monofilament nylon line sufficiently long to reach from the hook on the pan support to the straddle when the latter is in position across the pan. Attach the test specimen to the wire or line so that it is suspended 20 to 30 mm above the straddle when the other end of the wire is attached to the hook.
9.2 Weigh the suspended specimen to the nearest 1 mg and record this weight as a. Fill a 400 or 600-mL beaker two-thirds full with freshly boiled distilled water containing a small amount of detergent (Note 1). Adjust the temperature of the water to 25.0 +/- 0.2°C and maintain this temperature during the remainder of the test. Place the beaker with water on the straddle with the specimen, still suspended, fully submerged. When positioned correctly the beaker should not interfere with the movement of the balance. Remove any air bubbles adhering to the specimen or wire by means of a thin wire; then weigh the immersed specimen to the nearest 1 mg. Record this weight as b.
NOTE 1 - About 100 mg of Alconox to 200 mL of water has been found satisfactory.
9.3 Repeat the determination with the second test specimen.
10. Calculation
10.1 Calculate the relative density of the material under test as follows:
Relative Density at 25°C = a/(a - b)
where:
a = weight of the specimen in air, mg, and
b = weight of the specimen in water at 25.0°C, mg.
