ASTM D402 Method for Distillation of Cut-Back Asphaltic (Bituminous) Products
8. Procedure
8.1 Correct the temperatures to be observed in the distillation if the elevation of the laboratory at which the distillation is made deviates 150 m or more from sea level. Corrected temperatures for the effect of altitude are shown in Table 1 and Table 2. If the prevailing barometric pressure in millimetres of mercury is known, correct the temperature to be observed with the corrections shown in Table 3. Do not correct for the emergent stem of the thermometer.
NOTE 2 - Table 3 covers a wide range of temperatures from 160 to 360°C (320 to 680°F) and is to be preferred for world-wide specifications other than ASTM/IP specifications.
8.2 Apply heat so that the first drop of distillate falls from the end of the flask side-arm in 5 to 15 min. Conduct the distillation so as to maintain the following drop rates, the drop count to be made at the tip of the adapter:
50 to 70 drops per minute to 260°C (500°F)
20 to 70 drops per minute between 260 and 316°C (500 and 600°F)
Not over 10 min to complete distillation from 316 to 360°C (600 to 680°F)
8.2.1 Record the volumes of distillate to the nearest 0.5 mL in the receiver at the corrected temperatures. If the volume of distillate recovered is critical, use receivers graduated in 0.1-mL divisions and immersed in a transparent bath maintained at 15.6 more or less 3°C.
NOTE 3 - Some cut-back asphaltic products yield either no distillate or very little distillate over portions of the temperature range to 316°C (600°F). In this case it becomes impractical to maintain the above distillation rates. For such cases the intent of the method shall be met if the rate of rise of temperature exceeds 5°C (9°F)/min.
8.3 When the temperature reaches the corrected temperature of 360°C (680°F), cut off the heat and remove the flask and thermometer. With the flask in a pouring position, remove the thermometer and immediately pour the contents into the residue container. The total time from cutting off the heat to starting the pour shall not exceed 30 s. When pouring, the side-arm should be substantially horizontal to prevent condensate in the side-arm from being returned to the residue.
NOTE 4 - The formation of skin on the surface of a residue during cooling entraps vapors which will condense and cause higher penetration results when they are stirred back into the sample. If skin begins to form during cooling, it should be gently pushed aside. This can be done with a spatula with a minimum of disturbance to the sample.
8.4 Allow the condenser and any distillates trapped in the condenser neck to drain into the receiver and record the total volume of distillate collected as total distillate to 360°C (680°F).
8.5 When the residue has cooled until fuming just ceases, stir thoroughly and then, when the material reaches 135 more or less 5°C (275 more or less 9°F), pour into the receptacles for testing for properties such as penetration, viscosity, or softening point. Proceed as required by the appropriate ASTM or IP method from the point that follows the pouring stage.
8.6 If desired, the distillate, or the combined distillates from several tests, may be submitted to a further distillation, in accordance with Test Method D86 - IP 123, or, when the distillate is of coal-tar origin, Method C.O.3.
