ASTM D3461 Test Method for Softening Point of Asphalt and Pitch
ASTM D3461 Standard Test Method for Softening Point of Asphalt and Pitch (Mettler Cup-and-Ball Method)
10. Procedure
10.1 The procedure described in this test method for measuring the softening point of asphalts and pitches using a Mettler instrument has been developed to duplicate the results obtained by Test Method D36.
10.2 Preset the temperature of the furnace from 20 to 25°C below the expected softening point of the specimen and maintain at this temperature for a few minutes (see Note 2). Place the specimen cup in the cartridge with the lead ball carefully centered on top of the specimen. The ball may be warmed slightly to form a small indentation and ensure its proper positioning in the furnace during the test. Place the cartridge assembly in the furnace, taking care that the slits for the light beam are properly positioned. Wait for temperature equilibration, that is, the furnace and the sample are in equilibrium at the preset temperature, but not less than 30 s after inserting the cartridge, start the automatic heating cycle at 2°C/min. Heating will be maintained at this rate until the drop point is reached, after which a steady temperature will be displayed on the digital readout. Record this temperature as the softening point of the specimen.
NOTE 2 - In the event of a dispute, the purchaser and supplier shall agree on the exact starting temperature to be used.
10.3 Immediately remove the cartridge assembly upon completion of the test. Check to ensure that the sample has passed through the light beam and no pretriggering has occurred. If a malfunction is suspected, reject the result and repeat the test. Inspect the apparatus closely to ensure that no particles of residue remain.
10.4 Clean the specimen cups by placing them upside down on a hard surface and punching out any residual material. Use a spatula, shaped to the contour of the cup, with a swirling motion to remove any remaining particles. Inspect and clean the lead ball to remove any residue. Take care to avoid any distortion during this step. Washing with xylene, or other suitable solvent, may be necessary to get the apparatus completely clean.
