Description of Slow Curing Cutback Bitumen

Asphalt cutback use petroleum solvents for dissolving asphalt cement. The solvents are variously called distillate, diluents or cutter stock. If the solvent used in making the cutback asphalt is highly volatile, it will quickly escape by evaporation. Solvents of lower volatility evaporate more slowly. On the basis of the relative speed of evaporation, cutback asphalts are divided into three types: rapid curing (RC), medium curing (MC) and slow curing (SC).

agent to bitumen to reduce (or cutback) the viscosity of the bitumen. The mixture obtained may be called cutback bitumen.
The reduction in viscosity of the bitumen aids the construction of seal coats in road pavements as the softened mixture wets the chips more easily. The cutback agent evaporates from the seal coat, the cutback agent becoming a negligible component of the seal coat a few months after application. If significant amounts of the cutback agent remain in the seal coat an unwanted long term softening effect may result.

Slow Curing Cutback Bitumen cement and oils of low volatility generally in the heavy distillate range (SC-70, 250, 800, 3000). The degree of liquidity developed in each case depends principally on the proportion of solvent to asphalt cement. To a minor degree, the liquidity of the cutback may be affected by the hardness of the base asphalt from which the cutback is made. The degree of fluidity results in several grades of cutback asphalt—some quite fluid at ordinary temperatures and others somewhat more viscous. The more viscous grades may require a small amount of heating to make them fluid enough for construction operations.

Slow curing (SC) cutback asphalts are often called road oils and are used primarily in road-mixing and dust-laying applications. This term originated in earlier days when asphalt residual oil was used to give roads a low-cost, all-weather surface. SC cutback asphalts are also used for stockpile patching mixes, plant-mixed with graded aggregates and occasionally for priming.

Slow Curing Cutback Bitumen Applications

Current common uses are in penetrating prime coats and in producing patching or stockpile mixtures. Cutback asphalt used in mixing with aggregate will usually contain an adhesion agent to assist in the coating of the aggregate surface.

Cutback agents are used to lowering the viscosity of bitumen when it is applied as a primer to the surface of a road pavement aggregate base course or substrate. Kerosene is used as a bitumen cutback agent at different concentrations according to local conditions and requirements.
The cutback bitumen is ideal for prime coat and cold applied because of easy uses and no need to thinning and heating.

Cutback bitumen SC consist of initial incorporation of asphalt into the surface of non-asphalt based course preparatory to any superimposed treatment of construction.
The cutback asphalt SC applying to waterproofing of surfaces, plug capillary voids, coat and bond loose mineral particles.

Advantages of Slow Curing Cutback Bitumen

Slow curing cutback bitumen offers several advantages due to its slower evaporation rate compared to other types.
Key Advantages:

• Deeper Penetration: The extended curing time allows for deeper penetration into the underlying surface, resulting in a stronger bond and improved adhesion.
• Enhanced Durability: This deeper penetration contributes to a more durable and long-lasting pavement structure.
• Suitable for Cold Weather: Due to its slower evaporation rate, it can be effectively used in colder climates where rapid curing bitumen might not perform optimally.
• Versatility: Slow curing cutback bitumen can be used in various applications, including surface dressing, patching, and stabilization of base courses.
• Cost-Effective: In some cases, it can be more cost-effective than other types of bitumen due to its slower curing and potential for reduced material usage.