11. Procedure
11.1 Place 10 to 150 g (80 to 90 % of the maximum capacity of the particular holder being used) of the prepared crushed and sized fraction into the required specimen holder provided with the instrument. Weigh to the nearest milligram.
11.2 Determine volume of pitch following manufacturer's instructions.
11.3 Weigh specimen container after determination; if this weight is lower than the initial weight, the specimen has lost moisture or volatiles during the density determination. Use the lower weight in determining the density. Also, if the specimen appears to have free moisture, dry the specimen as specified in 8.1, and repeat the density determination.
11.4 Record the room temperature during the density determination.
12. Calculation
12.1 The procedure described in this test method determines the volume of a given mass of pitch at the ambient temperature (room temperature) of the helium pycnometer. Since the volume of a given mass of pitch is temperature-dependent, the density of the given specimen will vary with the ambient temperature. The variation of pitch volume with temperature has been previously established (Method D2962 and the literature), and the following calculation corrects all density measurements to 25°C.
12.2 The density of pitch, corrected to 25°C, is given by the general formula:
where:
W = specimen mass, g,
Vt = volume of specimen, cm3, at measurement temperature,
Δt = difference between 25°C and the measurement temperature, and
d25°C = pitch density at 25°C, g/cm3.
The factor 0.00047/°C is obtained from the literature and Method D2962.
12.3 Calculate the density of the pitch (to three decimal places) using the following equation:
The correction factors for measurement temperatures of 15 to 35°C are given in Table 1.
12.4 Example - A specimen of pitch having a mass of 20.027 g was found to have a volume of 15.26 cm3 at a temperature of 30°C; the density calculation is as follows:
12.5 Average duplicate results and round off to two decimal places.