9 - The Preparation and Properties of Bitumen Emulsion Stabilized by Cationic Surface-Active Agents

Abstract

Abstract Bitumen emulsions have been prepared using a colloid mill in the presence of four different cationic surface-active agents. These were, dodecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, dodecylammonium chloride and N -dodecyl, propylene 1,3-diamine hydrochloride. The particle size distributions of the emulsions showed that 90 per cent of the particles had diameters in the range 1 to 5 μm. The effect of type of surface-active agent, concentration of surface-active agent and electrolyte concentration on the electrophoretic mobility of the emulsion droplets was examined. It was found that the droplets acquired a constant positive mobility at a surface-active agent concentration just below the critical micelle concentration. The stability of the emulsions to electrolyte was studied and also the rate of heterocoagulation of the emulsion droplets with quartz particles. In addition, the adsorption of the cationic surface-active agents onto quartz surfaces was determined and the influence of the surface-active agents on the electrophoretic mobility of quartz particles examined. Correlation of the experimental data obtained by various techniques enabled a mechanism to be suggested for the breaking of bitumen emulsions on quartz surfaces.