ASTM D3461-18 PDF Download

The ASTM D3461-18 standard is a method used to determine the softening point of asphalt and pitch. This test is important in establishing the consistency and uniformity of shipments or sources of supply.

Asphalt and pitch do not have true melting points, as they do not undergo a solid-liquid phase change when heated. Instead, they gradually soften or become less viscous. Therefore, the softening point determination must be made using an arbitrary, but well-defined, method to ensure reproducible test values.

This test method utilizes a cup-and-ball apparatus to measure the softening point, which is the temperature at which the asphalt or pitch shows a specific amount of penetration under prescribed test conditions. The test range for the softening point is from 50 °C to 180 °C.

If the softening point of asphalt determined by the Mettler cup-and-ball method does not meet specified requirements, the test may be rerun using the ring-and-ball softening point apparatus (Test Method D36) as a referee method.