Preparation of highly concentrated bitumen emulsions by catastrophic phase inversion: Follow-up of the emulsification process

•When bitumen is emulsified via HIPR, a catastrophic phase inversion takes place.•HIPR bitumen emulsification includes phase inversion and size reduction by stirring.•Viscosity monitoring allows describe the mechanism bitumen emulsification at HIPR.•Each formulation may be characterized by a kinetic of emulsification.

This study focuses on the mechanisms of bitumen emulsification and on the impact of the formulation, when emulsification is carried out in the area of high internal phase ratio (0.9). Kinetics of emulsification were determined using systemic rheology coupled with optical microscopy observations. Microscopic observations revealed a catastrophic phase inversion with formation of abnormal multiple emulsions, occurring very quickly after contacting the bitumen with the aqueous phase containing the surfactant. The direct emulsion thus obtained is then refined during a subsequent agitation step. The viscosity follow-up during the emulsification highlights four steps in the kinetic of catastrophic phase inversion, which have been related to morphological characteristics of the dispersions observed by optical microscopy.

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