Asphalt cement grade of bitumen is one of the main categories of viscosity grade bitumen in which the viscosity of the standard bitumen is measured at 60 ºC (140 ºF) in units of 100 poises. AC grading specifies asphalt binder properties prior to the hot mix asphalt (HMA) production process. Hence, it should provide a more accurate representation of how asphalt binder behaves within HMA pavements.
6 categories of this type of grade with different viscosity are:
AC-2.5 is softest and means asphalt cement with a target viscosity of 250 poises at 60˚C which is mostly used in cold climates.
AC-40 is hardest and means asphalt cement with a target viscosity of 4000 poises at 60˚C is generally suitable for the regions with hot climate.