Cutback bitumen

Cutback Bitumen ( Liquid Bitumen ) is Bitumen that is dissolved in a solvent . The aim is to decrease the viscosity and to increase the penetration of bitumen on the asphalt surface. In comparison with bitumen, cutback bitumen is sprayed on different layers of roads at a notably lower temperature. Once the solvent is evaporated, the remaining bitumen equals penetration bitumen in terms of hardness.  Typical solvents include Naptha, gasoline and kerosene, white spirit, etc. The type of solvent controls the curing time while the amount determines the viscosity of the Cutback Bitumen.

The advantage Cutbacks have over Emulsions is a much higher residual Bitumen percent, typically over 80% compares with over 40-65% for Bitumen emulsions. The result is more Bitumen left on the roadway after curing, for the same volume of binder applied.

Cutbacks are divided into two classifications, Rapid-Curing (RC) Slow-curing (SC) and Medium-Curing (MC) depending on the solvent used. They are further defined by a number that indicates the minimum kinematic viscosity (fluidity) of the cutback. RC is recommended for surface dressing and patchwork. MC is recommended for premix with less quantity of fine aggregates. SC is used for premix with the appreciable quantity of fine aggregates.