ASPHALT EMULSIONS - FLOCCULATION INDUCED BY A CATIONIC SURFACTANT ANDAPPLICATION TO SIZE PARTITIONING

The effect of excess surfactant on cationic asphalt-in-water emulsions is investigated. At sufficiently high surfactant concentrations, reve rsible flocculation occurs in polydisperse emulsions. We interpret suc h a phenomenon as a fluid-solid phase transition due to the depletion interactions exerted by surfactant micelles. Taking advantage of this reversible transition, successful size partitioning is performed follo wing a fractionated crystallization technique recently developed. Expe rimental phase diagrams of monodisperse emulsions and microscopic obse rvations confirm the fluid-solid description of this transition. The i nfluence of an added electrolyte is also examined.