Emulsjonbitumen

Emulsjonbitumen is a colloidal system in which bitumen is dispersed as fine droplets in water, stabilized by surfactants or polymers to form a stable emulsion. It is produced by forcing hot bitumen through a high-shear mixer into a water-based phase with emulsifiers, at ambient or moderate temperatures. The resulting product can be applied without heating, making it a versatile material in road construction and maintenance.

Most emulsions are either cationic or anionic, depending on the charge of the emulsifier. Cationic emulsions tend to bond well to negatively charged mineral aggregates and are commonly used with standard mineral mixes, while anionic emulsions may be preferred for lime-containing or positively charged aggregates. Nonionic emulsions are less common but used in specialized applications.

Droplet size typically ranges from 1 to 20 micrometers; size and stability depend on formulation and processing. Set time can be rapid or slow, influencing when traffic can resume. Storage stability and heat resistance vary; many emulsions are designed to break and release bitumen upon drying, leaving a film that bonds to aggregates.

Applications include cold-mixed asphalt for patch repairs, surface treatments such as chip seals and slurry seals, and tack coats between successive layers. Emulsions enable low-temperature application, reduced energy use, and easier handling compared with hot mix asphalt.

Advantages include reduced emissions and energy, safer handling, and lower mixing temperatures. Limitations include moisture sensitivity, aging, and performance variations under extreme weather or heavy traffic; compatibility with aggregates is essential to prevent stripping. Environmental considerations focus on the water-based formulation, additives, and worker safety during handling and storage. Selection of emulsion type, grade, and curing conditions follows standard specifications and project requirements.