Softening Point

The softening point is useful in the classification of bitumens, as one element in establishing the uniformity of shipments or sources of supply, and is indicative of
the tendency of the material to flow at elevated temperatures encountered in service.

As bitumens are viscoelastic materials without sharply defined melting points; they
gradually become softer and less viscous as the temperature rises. For this reason,
softening points must be determined by an arbitrary and closely defined method if the
results are to be reproducible.