Cutback Bitumen RC-70 is a rapid-curing cutback asphalt produced by blending penetration grade bitumen with highly volatile petroleum solvents such as gasoline or naphtha. This formulation significantly reduces the viscosity of the base bitumen, allowing it to remain fluid at ambient temperatures and enabling efficient spraying and penetration into pavement surfaces.

RC-70 belongs to the Rapid Curing (RC) class of cutback bitumen, where the solvent evaporates quickly after application, leaving behind a strong asphalt residue with excellent bonding characteristics.

Definition and Material Characteristics

Cutback Bitumen RC-70 is manufactured from petroleum grade bitumen obtained through fractional and vacuum distillation of crude oil. The base bitumen is blended with a controlled percentage of fast-evaporating solvents to achieve rapid curing behavior in accordance with ASTM specifications.

Key material characteristics include:

• Medium-to-low viscosity at ambient temperature

• Rapid solvent evaporation and curing

• Strong adhesion to mineral aggregates

• Good penetration into granular and asphalt surfaces

• Thermoplastic behavior after curing

Cutback asphalts typically contain 12% to 40% distillate, and ASTM standards permit up to 45% distillate for rapid-curing grades such as RC-70.

Meaning of RC-70 Classification

The designation RC-70 indicates:

• RC (Rapid Curing): Use of highly volatile solvents that evaporate quickly

• 70: Viscosity classification measured at 60°C

This viscosity range makes RC-70 especially suitable for tack coats, spray applications, and light mixing operations where faster setting than RC-30 is required.

Performance Characteristics

Cutback Bitumen RC-70 provides:

• Fast curing and early strength development

• Reliable bonding between pavement layers

• Uniform spraying behavior using standard distributor trucks

• Effective coating of aggregates when used in patching mixes

• Good rheological performance after solvent evaporation

Its rapid curing nature allows traffic to be restored quickly after application when used under proper conditions.

Applications of Cutback Bitumen RC-70

Typical applications of Cutback Bitumen RC-70 include:

• Tack coats between asphalt layers

• Penetrating prime coats

• Patching and stockpile asphalt mixtures

• Surface spraying and pavement maintenance works

RC-70 is commonly applied on asphalt or granular surfaces using truck-mounted spray equipment, ensuring uniform coverage and effective bonding.

Safety, Handling, and Environmental Considerations

Due to the presence of volatile solvents, strict safety measures must be followed:

• Refer to the Safety Data Sheet (SDS) before use

• Transport, store, and apply at the lowest feasible temperature

• Eliminate all ignition sources during handling and application

• Avoid inhalation of vapors and contact with skin

• Always wear appropriate personal protective equipment (PPE)

• Prevent contamination of soil, stormwater, and sewer systems

Compliance with safety and environmental regulations is essential when using cutback bitumen products.

Packing and Supply

Cutback Bitumen RC-70 is supplied in:

• Bulk tanker trucks for large-scale projects

• New thick steel drums placed on pallets to prevent leakage during handling and transportation

Packaging options are suitable for both construction and maintenance operations.

Technical Specification – Cutback Bitumen RC-70

Standard: ASTM D2028-97 (Reapproved 2004)

Conclusion

Cutback Bitumen RC-70 is a rapid-curing asphalt binder designed for tack coats, prime coats, spraying operations, and maintenance applications where fast setting and strong interlayer bonding are essential. Its controlled viscosity, quick curing behavior, and reliable performance make it a practical solution for pavement construction and rehabilitation projects when used with proper safety and environmental controls.