AC bitumen

Asphalt cement grade of bitumen (AC bitumen) is one of the main categories of viscosity grade bitumen. The American Association of State Highway Official (AASHTO) has classified viscosity grade bitumen into two categories as follow. First one is AC, which stands for Asphalt Cement, and the second one is AR, which is the abbreviated form of Aged Residue.

It is a Most AC binders are used in hot applied surface treatments, but other uses include pre-coating, tack coat, and recycling. The AC nomenclature uses numbers to indicate the stiffness or viscosity of the asphalt. As the number get higher, the binder gets stiffer/harder. Designations are added for polymer additives (SBR for styrene-butadiene-rubber, P for styrene-butadiene-styrene block copolymer, and TR for tire rubber). Application temperatures of asphalt cements, especially the more viscous grades, are from 300°F to 400°F.

The difference between AR and AC grade is in the meaning of the numbers following them in written form. AC grade is followed by a number which indicates the viscosity at 60 c while AR grade is followed by a number which indicates the viscosity at 60 c after the bitumen has been aged.

Here are 6 asphalt cement (AC) grades: AC-2.5 (which is the softest grade), AC-5, AC-20, AC-30, and AC-40(which is the hardest grade). As a brief explanation, AC-2.5 is asphalt cement with a target viscosity of 250 poises at 60c. (250 are divided by 100).