Emulsion classifications and common uses

  • Cationic
  • Anionic
  • Nonionic (usually treated as a subset of the anionic classification)

Each classification is based on the electrical charge on the asphalt particles surface. The particle charge is determined by the emulsifier and the water pH.

Cationic

  • Definition – having a positive electrical charge
  • The emulsifier has a positive charge
  • Since the emulsifier coats the asphalt particle surface, all of the particles have a positive charge

Anionic

  • Definition – having a negative electrical charge
  • The emulsifier has a negative charge
  • Therefore, all the asphalt particles have a negative charge

Nonionic

  • Definition – having no electrical charge
  • The emulsifier does not have a charge
  • The asphalt particles also have no charge
  • Particles are protected by a viscous layer formed by the emulsifier

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Common Cationic Classifications

  • CRS, CMS, CQS, and CSS
  • Each classification will have a suffix such as “-1” or “-2” (emulsion viscosity) and/or and “h” (asphalt base hardness)
  • Examples: CRS-2, CQS-1h, CSS-1
  • Other designations: P=polymer (solid or latex) LM=latex polymer, s=solvent, many others…

Common Anionic Classifications

  • RS, HFRS, MS, HFMS, QS, and SS
  • Each classification will have a suffix such as “-1” or “-2” (emulsion viscosity) and/or and “h” (asphalt base hardness)
  • Examples: HFRS-2, SS-1h
  • Other designations: P=polymer (solid or latex) LM=latex polymer, s=solvent, many others…

Other Classifications

  • Dozens of other classifications are used by state and local agencies for specialized purposes
  • Many proprietary emulsion systems exist that will have other designations

Why do we have different classifications?

  • Producing an emulsion that is stable for storage or
    handling is easy…
  • …but emulsions must be designed to break at exactly the
    right time in the construction process and perform well
    over the long-run

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Spray grade emulsions (rapid and medium sets)

  • Designed to be marginally stable
    – The chemical additives and dosages are chosen to allow reasonable handling stability, but easy destabilization
  • Break with mild destabilizing effects
    – Environmental exposure and/or on contact with flat surfaces

Mixing Grade

  • Slurry seals
  • Micro-surfacing
  • Cape seals (the slurry portion only)
  • Cold mixes (solvent and solventless)
    – Base stabilization, full depth reclamation, cold-in-place recycling, virgin aggregate intermediate and wearing courses, and patch mixes

Mixing grade emulsions are also used in spray grade applications

  • In cases where nonstandard materials are used or fast return to traffic is not required
  • Where the spraying application experiences challenging conditions

Mixing grade emulsions in spray applictions

  • Tack coats and fog seals – diluted for weeks, pumped multiple times
  • Chip seals – where dense graded or dusty aggregates are used
  • Prime coasts – emulsion stability needed to allow penetrations in the base

 

обновлено: July 4, 2016 автором: dannik