VG (Viscosity Grade) & CG (Cutback Grade)

VG — Viscosity Grade bitumen
Viscosity Grade (VG) bitumen is classified by its viscosity at specific temperatures rather than by penetration. VG grades (for example VG-10, VG-30, VG-40) indicate how fluid or stiff the bitumen is at service or mixing temperatures. VG bitumen is supplied as the neat product (no solvents) and is typically heated during mixing and paving. It is widely used for standard asphalt mixes and heavy-traffic pavements because its properties are stable and predictable over time.

CG — Cutback Grade bitumen
Cutback bitumen is produced by dissolving bitumen in a volatile petroleum solvent to reduce viscosity so it can be handled and applied at lower temperatures. After application the solvent evaporates, leaving the bitumen film. Cutbacks (often identified by numbers that indicate viscosity or solvent type) are useful where on-site heating is impractical or when quick spreading at ambient temperature is needed — for example in priming, tack coats, or surface treatments. Because solvents evaporate, cutbacks may have faster curing but lower long-term durability compared to neat bitumen.

Feature	VG (Viscosity Grade)	CG (Cutback Grade)
Composition	Neat bitumen, no solvent added.	Bitumen dissolved in a volatile solvent to reduce viscosity.
Classification basis	Classified by measured viscosity at specified temperatures (e.g., VG-30).	Classified by formulation and viscosity with solvent; sometimes indicated by numerical codes.
Handling / application	Requires heating for mixing and paving.	Can be applied at lower temperatures; no or less heating needed thanks to solvent.
Durability	High long-term stability and durability when properly applied.	Good short-term workability; long-term performance can be reduced due to solvent effects and evaporation.
Typical applications	Asphalt mixes, road paving, heavy-traffic pavements.	Priming, tack coats, surface treatments, jobs where heating is difficult.