Performance Grade, the binder classification written as two numbers in degrees Celsius, such as PG 64-22. The first number is the high pavement temperature at which the binder still meets its stiffness requirement against rutting; the second is the low temperature it can reach before it gets too stiff and cracks. Grades step in 6-degree increments, and the rating comes from DSR, BBR and aging tests run on fresh, RTFO-aged and PAV-aged samples.
Spec calls for PG 76-22 on the surface lift through the truck stop, so the tanker's bringing modified oil tomorrow.
Rule of 90: when the high and low numbers add up to more than 90, ignoring the minus sign, the binder almost always needs polymer to get there.
Also heard as
- performance grade
- PG grade
Related terms
Asphalt binder
The black, sticky petroleum cement that glues the aggregate together in an asphalt mix.
DSR
Dynamic shear rheometer: the instrument that measures a binder's stiffness and elasticity by twisting a thin disk of it.
BBR
Bending beam rheometer: the test that checks how stiff and brittle a binder gets at low temperature.
MSCR
Multiple stress creep recovery: a high-temperature binder test measuring how much of a deformation the binder recovers.
Polymer-modified asphalt
Binder blended with an elastic polymer, usually SBS, to resist rutting in heat and cracking in cold.