June 18, 2008

Bitumen Emulsions

Bitumen Emulsions

Bitumen emulsion is a combination of three basic ingredients, Bitumen, water, and small amount of an emulsifying agent. These ingredients are introduced into a process which shears the bitumen into tiny droplets. The emulsifier, which is a surface-active agent, keeps the Bitumen droplets in a stable suspension and controls the breaking time. The final product is a liquid product with a consistency ranging from that of milk to heavy cream and can be used in cold processes for road construction and maintenance.

Advantages of Bitumen emulsions

Bitumen emulsion does not require a petroleum solvent to make it liquid and in most cases Bitumen emulsions can be used without additional heat. Both of these factors contribute to energy savings. Additionally, Bitumen emulsions offer great flexibility in their application since they offer the end-user a great variety of characteristics not found in other paving and maintenance materials. Bitumen emulsions are environmentally friendly. There are little or no hydrocarbon emissions created with their use.

History of Bitumen emulsions

Bitumen emulsions were first prepared in the early part of the 20th century and today they are used all over the world. The use of Bitumen emulsions is growing and 10-20% of all Bitumen is used in the form of Bitumen emulsions.

Classification of Bitumen emulsions

Bitumen emulsions are classified into three categories;

  • Anionic
  • Cationic and
  • Nonionic

The anionic and cationic classes refer to the electrical charges surrounding the Bitumen particles. The absence of the letter "C" denotes anionic emulsions.

Bitumen emulsions are further classified on the basis of how quickly they coalesce; i.e., revert to Bitumen cement.

RS (Rapid Set),

MS (Medium Set), SS (slow set), and

QS (Quick Set)

have been adopted to simplify and standardize this classification.

Additionally, trailing numbers are used to delineate the relative viscosity if the emulsion and the letters "h" and "s" indicate whether a hard or soft base Bitumen is used to make the Bitumen emulsions.

Thus, a CSS-1h is a cationic slow set emulsion with a relatively low Bitumen emulsion viscosity made with a hard base Bitumen.

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