Introduction

Emulsion bitumen CRS, a specialized form of bitumen used in road construction, has gained significant traction in recent years due to its unique properties and versatile applications. Emulsion bitumen CRS, which stands for Cationic Rapid Setting, offers a range of benefits that make it an ideal choice for various road construction projects.

Emulsion bitumen CRS is typically produced by subjecting a mixture of hot bitumen and a water phase to mechanical forces, such as those generated by a rotating disc, cone, or wheel, along with a stator. During the emulsification process, the hot binder is mechanically broken down into tiny droplets and dispersed in water, which has been treated with a small amount of an emulsifying agent. In this process, water functions as the continuous phase, while the tiny binder droplets serve as the discontinuous phase. By carefully selecting the emulsifying agent and applying manufacturing controls, various types and grades of emulsified asphalts are manufactured. The choice of emulsifying agent determines whether the emulsified asphalt is:

• Anionic – with negatively charged binder droplets.
• Cationic – with positively charged binder droplets.

Moreover, through adjustments in materials and production methods, emulsified asphalts of both anionic and cationic varieties are produced in multiple grades. Some examples of these grades and their applications include:

• Anionic (non-Virginia grades):
  • RS-2: Used for tack and seal coat applications.
  • SS-1H: Employed in slow-set slurry and tack uses.
• Cationic (Virginia grades):
  • CRS-2: Utilized for tack and seal coat purposes.
  • CRS-1: Applied as a tack coat.
  • CRS-1H: Used as a tack coat.
  • CSS-1H: Available in two types for slurry (rapid set and slow set) and tack use.
  • CRS-2: Applied as a prime coat, tack coat, seal coat, and cold mix (contains 7-12% solvent).

Because particles with the same electrostatic charge repel each other, the asphalt droplets remain separate until the emulsion is deposited onto the surface of soil or aggregate particles. Emulsified asphalts can be used with both cold and heated aggregates, regardless of whether the aggregates are dry, damp, or wet.