Cutback Bitumen SC-250 is a slow-curing cutback asphalt formulated by blending petroleum grade bitumen with low-volatility distillates, typically gas oil. This process reduces the viscosity of the base bitumen, allowing it to remain workable at ambient temperatures while curing gradually through solvent evaporation.

SC-250 belongs to the Slow Curing (SC) family of cutback bitumen, also widely known as road oil, and is specifically designed for applications requiring deeper penetration, longer curing time, and higher residual binder content compared to lighter SC grades.

Definition and Material Characteristics

Cutback Bitumen SC-250 is produced from penetration grade bitumen obtained through fractional and vacuum distillation of crude oil. The base bitumen is fluxed with less volatile petroleum distillates, resulting in a material with:

• Higher viscosity compared to SC-70
• Slow evaporation rate
• Strong bonding and sealing capability
• Excellent penetration into untreated or granular base layers
• Thermoplastic behavior after curing

SC cutback asphalts such as SC-70 and SC-250 are chemically similar to heavy refinery residual products like fuel oil No.6 (Bunker C).

Meaning of SC-250 Classification

The designation SC-250 indicates:

• SC (Slow Curing): Use of low-volatility cutback agents
• 250: Higher kinematic viscosity range measured at 60°C

This higher viscosity makes SC-250 suitable for applications where greater binder retention and slower curing are required before final pavement treatments.

Performance Characteristics

Cutback Bitumen SC-250 provides:

• Deep penetration into granular and non-asphalt base courses
• Effective waterproofing and sealing of capillary voids
• Strong bonding of loose mineral particles
• Uniform coating without the need for heating
• Longer working and curing time compared to SC-70

These properties make SC-250 ideal for preparatory pavement treatments and cold-applied operations.

Applications of Cutback Bitumen SC-250

Typical uses of Cutback Bitumen SC-250 include:

• Prime coat applications on granular base and sub-base layers
• Cold-applied waterproofing treatments
• Surface penetration and dust suppression
• Patching and stockpile asphalt mixtures
• Initial surface preparation prior to asphalt surfacing

SC-250 is particularly effective where controlled absorption and long curing periods are essential for pavement durability.

Safety, Handling, and Environmental Considerations

Due to the presence of petroleum distillates, the following precautions must be observed:

• Refer to the Safety Data Sheet (SDS) prior to use
• Store and apply at the lowest practical temperature
• Eliminate all ignition sources during application
• Avoid inhalation of vapors and direct skin contact
• Use appropriate personal protective equipment (PPE)
• Prevent discharge into soil, drains, or water systems

Packing and Supply

Cutback Bitumen SC-250 is supplied in:

• New thick steel drums placed on pallets to prevent leakage
• Bulk bitutainers
• Bulk tanker trucks for large-volume projects

Packaging options are designed for safe transportation and efficient on-site use.

Technical Specification – Cutback Bitumen SC-250

Standards: ASTM / EN 15322:2009

Property	Min	Max	Test Method
Kinematic Viscosity @ 60°C, mm²/s	250	500	ASTM D2170
Flash Point (Cleveland Open Cup), °C	60	—	ASTM D92
Distillation Test			ASTM D402
Total Distillate to 360°C, vol %	—	25	ASTM D402
Solubility, %	95	—	ASTM D2024
Kinematic Viscosity of Residue @ 60°C, mm²/s	400	10000	ASTM D2170
Asphalt Residue
Residue of 100 Penetration, %	50	—	ASTM D243
Ductility of Residue @ 25°C, cm	50	—	ASTM D113
Water Content, %	—	0.5	ASTM D95

Conclusion

Cutback Bitumen SC-250 is a high-viscosity, slow-curing road oil designed for prime coats and cold applications where deep penetration, extended curing time, and strong waterproofing performance are required. Its controlled curing behavior and ease of application make it a reliable choice for pavement construction and maintenance projects under a wide range of site conditions.