Coasts Petroleum Products Co.

Coasts Petroleum Products Co.
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Cutback Bitumen

Cutback Bitumen is made by reducing the viscosity of and ordinary bitumen by adding mostly petroleum type solvent.

Cutback Bitumen is used because its viscosity is lower than that of neat asphalt and can thus be used in low temperature applications. After a cutback is applied the solvent evaporates away and only the bitumen is left. A cutback bitumen is said to cure as the petroleum solvent evaporates. Cutback bitumen are typically used as prime coats and tack coats. The aim is to decrease the viscosity and to increase the penetration of bitumen on asphalt surface. In comparison with bitumen, cutback bitumen is sprayed on different layers of roads with a notably lower temperature.

Cutback Bitumen is categorized into 2 groups, according to their curing time:

Rapid Curing (RC)

Rapid Curing Cutback Bitumen is made by reducing the viscosity of and ordinary bitumen by adding mostly petroleum type solvent. After a RC cutback is applied the solvent evaporates away and only the Bitumen is left. A rapid curing cutback bitumen is said to cure as the petroleum solvent evaporates. Rapid curing Cutback bitumen are typically used as prime coats and tack coats.

Medium Curing (MC)

MC grades cutback asphalt is simply a combination of asphalt cement and petroleum solvent. Like emulsions, cutbacks are used because they reduce asphalt viscosity for lower temperature uses (tack coats, fog seals, slurry seals, stabilization material). Similar to emulsified asphalts, after cutback asphalt is applied the petroleum solvent evaporates leaving behind asphalt cement residue on the surface to which it was applied.

Prime and Tack Coating

The process of priming involves applying a low viscosity binder to a prepared but usually unbound aggregate base. It is intended to be absorbed by the top layers of the base and provide a surface more easily ‘wetted’ by a subsequent bituminous covering. The primer will be able to carry traffic for a short time (although this practice is uncommon) and help control dust. Generally, primers are applied at rates between 0.5 and 1.4 L/m2. Cutback bitumen’s suitable for priming are also used for tack coats, which are applied to an underlying surface to help with the adhesion of subsequent asphalt layer. A typical application rate is between 0.2 and 0.4 L/m2.