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Classification and naming of bitumen emulsions , Selection of bitumen emulsions for various Road works

Bitumen emulsions are classified according to the electrolytic charge on the droplets and according to their reactivity(Setting Time). Cationic emulsions have droplets which carry a positive electrolytic charge where as anionic emulsions have negatively charged droplets , hence two types of bitumen emulsions.

Cationic – Positively charged droplets

Anionic – Negatively charged droplets

Also bitumen emulsions are named according to reactivity- Rapid setting ( RS)  emulsions sets quickly in contact with clean aggregates of low surface area such as chippings, Medium  setting ( MS) emulsions sets less quickly than rapid setting emulsions but sufficiently less quicker so that it can be mixed with aggregate of low surface area such as open graded mixes. Slow setting (SS) emulsions mix with reactive aggregates of high surface area. It should be noted that RS emulsions reactive( act quickly) and used with un reactive aggregates.

In naming emulsions according to ASTMD 977, and D2297 – Cationic emulsions are denoted as ;

CRS – Rapid setting

CMS—Medium setting

CSS – Slow setting

Where as Anionic emulsions are  named as RS, MS, and SS followed by a number and text denoting emulsion viscosity and residue properties—such as SS-1H  would mean slow setting anionic emulsion and hard bitumen residue.

The difference between CRS1 and CRS 2 would be CRS2 is with high viscosity. The quick setting (QS)  and Cationic quick setting ( CQS)designations have been used to emulsions with medium in reactivity between MS and SS.

Applications for road works.

The summary of Applications are given in the table  for quick guide. In general anionic emulsions are used with aggregates whose surface charged positively such as lime rock and cationic emulsions are used with aggregates whose surface charged negatively such as granite rocks.

ApplicationAnionicCataionic
RSMSSSRSMSSS
Plant Use
Open graded
Dense graded
Stock pile mix
Pre coated chips
Asphalt Mix paving
Open graded
Slurry
Slurry and chip seal
Micro surfacing
In place mixes
Dense Graded
Spray Applications
Chip seal
Fog seal and cement curing
Tack coat
Prime coat
Dust prevention
Penetration macadam
Other
Water proofing coats
Drive way footpaths sealing

 

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