Description
Slow Curing (SC) Cutback Bitumen is also referred to as a blend of asphalt cement and low-volatility petroleum solvents such as fuel oil or diesel. The blend reduces the viscosity of the bitumen, which is easier to use in cold weather or cold mix operations. “Slow curing” refers to the slow evaporation of the solvent, which is longer working time and more tolerant construction conditions.
SC Cutback Bitumen Mechanism
The content of the solvent in SC cutbacks is typically 5% to 25% of the total. Since the solvent evaporates very slowly, bitumen gradually hardens and sticks to the surface or aggregate and forms a hard pavement layer. It is especially suitable for applications that require longer storage, transportation, or utilization times.
SC Bitumen Grades Used More Frequently
SC cutback bitumen is available in a range of viscosity-based grades, each of which is intended for specific environmental and project conditions:
SC-3000
The figure indicates the kinematic viscosity in centistokes (cSt).
Applications of Slow Curing Cutback Bitumen
SC bitumen is widely applied in cold climate situations and remote construction sites, with the principal applications being:
Cold Mix Asphalt & Stockpile Mixtures
SC reductions allow for the manufacture of cold mix asphalt that will perform over long periods, and thus are utilized well for stockpiles and off-site delivery.
Penetrating Prime Coats
Applied straight to base courses of granular material, SC bitumen is a prime coat, penetrating and retaining loose materials before top-coat asphalt is applied.
Pavement Patching
Its longer workability life makes SC bitumen highly suitable for repairing damaged pavements, especially under cold weather or hot mix rural areas.
Waterproofing & Sealing
On application to surfaces, SC bitumen seals capillary pores and consolidates loose mineral grains, imparting resistance to water and weathering.
Environmental & Practical Benefits
No need for heating: SC bitumen can be applied in unheated form, saving energy and improving safety.
Extended shelf life: Can be stored in warehouses and transported over long distances to remote areas.
Multi-performance: Functions well in a range of climates, especially cold climates.
High bond: Increases adhesion of asphalt to untreated surfaces.
Summary
Slow Curing Cutback Bitumen is a versatile and easy-to-use material in road construction, with extended workability and strong adhesion characteristics. Used as a prime coat, patching compound, or in cold mix application, SC grades provide consistent performance without the need for heating. By selecting the appropriate grade (e.g., SC-70 or SC-3000), engineers can design results based on climate, application type, and transportation.
