Viscosity of bitumen emulsion

Bitumen emulsions are used at ambient temperatures, and as a result, an essential change in their viscosity can possibly have negative impacts or requirements for partial heating. Emulsion viscosity mainly affects the emulsion s ability to be successfully sprayed at ambient temperatures and to successfully coat the aggregates with bitumen. It also affects the workability of the cold bituminous mixture at the mixing and compaction stages. 

The same figure also presents the effect of temperature on the emulsion viscosity. As the temperature is reduced, the emulsion viscosity increases. This increase is more distinct to emulsions having a bitumen content of more than 65%. Moreover, the emulsion viscosity is affected by the bitumen viscosity during emulsification, the acidity of the aqueous solution and the emulsifier content (Shell Bitumen 2003). When the viscosity of the bitumen entering the colloid mill is reduced, the average diameter of particles is reduced and the emulsion viscosity slightly increases. Additionally, a relative increase of the viscosity is observed when the acidity of the aqueous solution is reduced and emulsifier content is increased. 

The grade of bitumen (hardness) used for emulsion production also affects the viscosity of the emulsion but to a lesser extent. The extent of influence depends on the type of emulsifier (Nikolaides 1983). The type of emulsifier also affects the Newtonian or non-Newtonian behaviour of the emulsion. 

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The rotational paddle viscometer measures the apparent viscosity of bitumen emulsions with viscosities between 30 and 1500 mPa-s (centipoises) at 50 C. 

The efflux or cup viscometers are used to determine the viscosity of bitumen emulsions and... 

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