: Cutbacks : : Emulsions : : PG Graded Asphalt Binders :

Liquid Asphalt / Cutbacks

Cutbacks are petroleum solvents used to dissolve asphalt cement. They are also referred to as distillates, diluents and cutter stock. When asphalt cement is dissolved in this manner it is referred to as cutback asphalt or cutback.

If the solvent used to make the cutback asphalt is highly volatile, it will evaporate quickly. The less volatile the slower the evaporation. On this basis, cutback asphalt is divided into three types:

• Rapid curing (RC) -- Asphalt cement and a light diluent of high volatility-generally in the gasoline or naphtha boiling point range (RC-70, 250, 800, 3000).
• Medium curing (MC) -- Asphalt cement and a light diluent of intermediate volatility-generally in the kerosene boiling point range (MC-38, 70, 250, 800, 3000),
• Slow curing (SC) -- Slow curing asphalts are often called road oils-from the days when asphalt residual oil was used to give roads a low-cost, all-weather surface.

The degree of fluidity in each case depends principally on the proportion of solvent to asphalt cement, though it may also be affected to a minor degree by the hardness of the base asphalt used to formulate the cutback. The degree of fluidity results in several grades of cutback asphalt. Some are fluid at ordinary temperatures while others are more viscous, requiring some heating to make them fluid enough for construction purposes.

Cutbacks are used for both road construction and specialty applications. The rapid setting grades are designed to react with aggregate, reverting quickly from a cutback to their asphalt state. These are primarily used in spray applications such as aggregate chip seals, sand seals, and similar surface treatments.