Heteroflocculation of a Cationic Oil-in-Water Emulsion Resulting from Fontainebleau’s Sandstone Powder Addition as a Model for Asphalt Emulsion Breakup

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The use of asphalt emulsions for road fabrication is rapidly gaining in importance mainly due to energy savings, less environmental impact, and better properties of the final product. However, the formulation of these emulsions still requires a better understanding, particularly concerning their breaking phenomena. When a cationic model emulsion is contacted with a solid having a negative-charged surface, physicochemical driving forces result in the emulsion destabilization. As a consequence, a viscosity reduction of the remaining emulsion is observed, as well as the emulsion breakup through a heteroflocculation mechanism provided the solid surface is large enough. Emulsion systems at equilibrium, containing cetylpyridinium chloride (CPC), paraffin oil, and Fontainebleau’s sandstone powder and having different droplet sizes, are studied. The results show that the dispersed oil fraction decreases after each addition of sandstone aliquots, and this depends on the concentration of CPC in the continuous phase of the emulsion. As the droplet size and distribution remain constant during the process, it is assumed that the emulsion heteroflocculation is the result of direct oil droplets adhesion on the sand surface, followed by their coalescence around the sand particles.