Cutback Bitumen is a liquid asphalt binder produced by dissolving penetration-grade bitumen in volatile petroleum solvents such as gasoline, kerosene, naphtha, or diesel oil.
The solvent temporarily reduces viscosity, allowing application at ambient temperatures without heating. After application, the solvent evaporates, and the bitumen regains its binding strength.
Cutback Bitumen is especially suitable for cold climates, remote locations, and maintenance works where hot-mix facilities are unavailable.
Manufacturing & Formulation Process
Base Bitumen Selection:
Typically penetration-grade bitumen such as 60/70 or 80/100.
Solvent Blending:
Gasoline → Rapid curing
Kerosene → Medium curing
Diesel / Heavy oil → Slow curing
Viscosity Adjustment:
Solvent content (20–55%) adjusted to achieve target viscosity.
Homogenization & Testing:
Final product tested as per ASTM D2027 / IS 217 standards.
Curing Mechanism
Application Stage:
Low-viscosity liquid penetrates pores and coats aggregates.
Curing Stage:
Solvent evaporates at a controlled rate.
Final Stage:
Remaining bitumen hardens to form a durable adhesive film.
Key Technical Characteristics
Low viscosity at ambient temperature – no heating required
Multiple curing options (RC / MC / SC)
Excellent adhesion to aggregates and granular bases
High penetration and surface sealing ability
Smooth spraying and spreading workability
Controlled setting time for repairs or base stabilization
Durable binder performance after curing
Typical Mechanical & Physical Properties
| Property | Typical Range |
|---|---|
| Viscosity @25°C | 30 – 10,000 cSt |
| Penetration @25°C | 60 – 300 dmm |
| Flash Point | 25 – 65°C |
| Specific Gravity | 0.95 – 1.10 |
| Solubility in Trichloroethylene | >99% |
| Distillation (Solvent Content) | 20 – 55% |
| Ductility | 50 – 100+ cm |
Cutback Bitumen Grades & Selection Guide
Rapid Curing (RC)
Solvent: Gasoline
Grades: RC-30, RC-70, RC-250, RC-800, RC-3000
Uses: Surface dressing, patching, tack coats
Note: Fast setting but higher fire & environmental risk
Medium Curing (MC)
Solvent: Kerosene
Grades: MC-30, MC-70, MC-250, MC-800, MC-3000
Uses: Prime coats, premix work, cold mixes
Most widely used category
Slow Curing (SC)
Solvent: Diesel / Heavy oil
Grades: SC-70, SC-250, SC-800, SC-3000
Uses: Road mixing, penetration macadam
Deep penetration with longer curing time
Environmental & Regulatory Considerations
Solvent evaporation releases VOCs
RC grades restricted in many regions
Increasingly replaced by bitumen emulsions and warm mix asphalt
Still used where performance benefits justify application
Packaging & Supply Options
Steel Drums (150–200 kg)
Bulk Tankers
IBC Containers
Custom packaging on request
Storage & Safety Guidelines
Store in well-ventilated areas
Keep away from ignition sources
Avoid direct sunlight and overheating
Use flame-proof equipment
PPE recommended during handling
Applications of Cutback Bitumen
Road Construction: Prime coats, tack coats, cold mix asphalt
Maintenance: Patching, pothole repairs, crack sealing
Industrial: Waterproofing, roofing felts, protective coatings
Rural & Emergency: Remote road works, temporary surfacing
Advantages of Cutback Bitumen
No heating required
Easy handling and application
Excellent penetration and adhesion
Suitable for cold and remote regions
Flexible curing options