March 12, 2011 | Leave a Comment
The bitumen content of cationic bitumen emulsion used in Australia is generally between 60 and 70 percent. Bitumen used is either Class B160 or Class B80. A cationic emulsion may be used to better advantage than an anionic emulsion with acidic types of aggregate, such as granite, or in damp conditions.
Cationic emulsions are classified, according to their setting (or braking) times, into rapid setting (CRS), slow setting (CSS) and aggregate mixing (CAM).
(a) Rapid Setting (CRS) : Rapid setting emulsion breaks rapidly on application. It is suitable for maintenance patching and sealing.
(b) Slow Setting (CSS) : Slow setting emulsion is suitable for soil stabilization.
(c) Aggregate Mixing (CAM) : Aggregate mixing emulsion contains a proportion of oil to delay its setting time when mixed with aggregate. It is normally used for making cold mix to be stockpiled and progressively used over a period.
Bitumen emulsion used as binders seldom require any preparation other than possible warming to about 450C to facilitate spraying in cold weather. Heating above 500C should be avoided otherwise premature breaking may occur.