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)
3. Summary of Test Method
3.1 In this test method the softening point is defined as the temperature at which the specimen, suspended in a cylindrical cup with a 6.5-mm hole in the bottom and with a lead ball, 8 mm in diameter, centered on top of the sample in the cup, flows downward a distance of 19 mm to interrupt a light beam, as the sample is heated at a linear rate in air.
4. Significance and Use
4.1 Asphalt and pitch do not go through a solid-liquid phase change when heated, and therefore do not have true melting points. As the temperature is raised, they gradually soften or become less viscous. For this reason, the determination of the softening point must be made by an arbitrary, but closely defined, method if the test values are to be reproducible.
4.2 This test method is useful in determining the consistency as one element in establishing the uniformity of shipments or sources of supply.
