Anionic Bitumen Emulsifying Agents

The history of bitumen and asphalt emulsions

Bitumen is commonly known to be a black viscous mixture of hydrocarbons obtained naturally or as a residue from the petroleum distillation process. It is difficult to handle at ambient temperatures. Increasing the temperature will alter the viscosity to a point where it can be handled, however, not without risk.

Application of the molten bitumen proved to be challenging at these elevated temperatures. Innovative ways to suspend bitumen with a soap solution can be traced back to 9 May 1922, where Hugh Alan Mackay an English Chemist first filed for a patent on how bitumen emulsions can be made.

This innovation paved the safe sustainable use of bitumen emulsions reducing greenhouse gas effects, reducing global warming foot prints and general worker safety.

Mackay claimed in the patent application, that the stable dispersion for a bitumen in water can be achieved through dispersing bitumen with high shear in water containing an emulsifier. This process is called emulsification.

Workers conduct waterproofing of the roof with bitumen.
Workers conduct waterproofing of the roof with bitumen.

Stable bitumen emulsions cannot be suspended indefinitely, however by carefully selecting the correct emulsifier, quantity and introducing a mechanical high shear mixer it can reduce the bitumen droplet size. This process by means of mechanical shear action, interaction of the bitumen and soap in the high shear mixing process can create a stable bitumen emulsion.

George Gabriele Stokes in 1851 derived an expression that “The force that resists a sphere’s fall in a viscous fluid directly proportional to the viscosity of the sphere, the radius of the sphere, and the viscosity of the fluid” known as Stokes law. Mackay and Gabriele influenced the basic understanding of emulsification by mixing two components to form the basis of our understanding of bitumen emulsions today.

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