Bitumen emulsions are playing an increasingly important role in modern road construction. As infrastructure demands evolve and sustainability targets rise, many road agencies and contractors are turning to emulsified bitumen for safer handling, improved application in cooler climates, and better environmental performance.
Unlike traditional hot-applied bitumen, bitumen emulsions can be used at lower temperatures, which reduces fuel consumption and lowers the risk of burns or fume exposure. In this guide, we explain what bitumen emulsions are, how they work, the types available, and how they are commonly used across global road networks.
What are bitumen emulsions?
Bitumen emulsions are a stable mixture of bitumen droplets suspended in water, typically with the help of an emulsifying agent. This emulsifier acts as a surfactant, keeping the bitumen and water phases separated long enough for the mixture to be applied in road construction. Once applied, the water phase begins to evaporate or “break,” allowing the bitumen to adhere to the surface or mix with aggregate as intended.
Because they can be sprayed or mixed without heating the bitumen to high temperatures, emulsions are safer and more energy-efficient in many site conditions. They are commonly used in surface dressing, tack coats, slurry seals, and cold mix asphalt production.
Key Properties and Performance Characteristics
Bitumen emulsions have a number of performance characteristics that determine their suitability for different applications. Viscosity, for example, affects how easily the emulsion can be pumped or sprayed, and influences how well it coats the surface or aggregate.
Another critical factor is the setting time—how quickly the emulsion breaks and leaves behind the residual bitumen. This varies by type and impacts the speed at which the surface can be trafficked. Storage stability is also important, particularly when emulsions are stored for extended periods. A stable emulsion will resist separation and maintain its consistency under agitation.
The amount of residual bitumen in the emulsion directly affects the durability of the final surface. Higher residual content generally improves performance, particularly in sealing or bonding layers.
Types of bitumen emulsions
Bitumen emulsions are classified into two main types, based on setting time and surface charge, these include:
Based on setting time
Slow Setting Emulsion
This type of emulsion is designed for applications that require a gradual process of water evaporation. It features a relatively stable emulsifying agent.
Medium Setting Emulsion
These emulsions are specifically formulated to prevent breaking when applied to aggregates. The process of evaporation starts when fine mineral dust mixes with the aggregate-emulsion mixture.
Based on Surface Charge
Anionic Bitumen Emulsion
In this type, tiny droplets of bitumen carry a negative charge. This facilitates better interaction with aggregates in certain mineral compositions.
Cationic Bitumen Emulsion
Tiny droplets of bitumen in cationic emulsions are electro-positively charged. Their usage depends on the mineral composition of the aggregates.
Applications in Road Construction
Bitumen emulsions are used in a range of construction and maintenance applications. Tack coats between pavement layers improve bonding and are often applied using rapid setting emulsions. Prime coats, used on granular base layers, prepare the surface for better adhesion.
In preventative maintenance, fog seals are sprayed over aged asphalt to reduce raveling and seal small cracks. For larger areas, slurry and micro surfacing provide thin, durable overlays that restore skid resistance and surface performance. Emulsions are also used in cold mix asphalt, allowing mixtures to be prepared and laid at ambient temperatures, particularly useful in remote locations or where heating resources are limited.
These varied applications make bitumen emulsions an essential material for flexible, cost-effective road treatments.
Storage and Handling Considerations
While emulsions are safer than hot bitumen to store and handle, they still require care. Tanks should allow for gentle agitation to prevent separation and should be constructed from compatible materials to avoid contamination. Temperature extremes should be avoided, as freezing or overheating can destabilise the emulsion.
TEC does not manufacture or supply emulsified bitumen, but our Bitutainer™ Storage Facility is well-suited for storing temperature-sensitive materials like bitumen emulsions, particularly when specified for that purpose. These systems can be deployed near plants or work sites, supporting efficient logistics for cold mix production or remote surfacing projects.
To understand more about safe heating and thermal control for bitumen, read our article on how bitumen is heated.
Bitumen emulsions continue to grow in importance across road construction and maintenance. Their safety, temperature flexibility, and wide range of applications make them ideal for projects in variable conditions or decentralised locations.
While TEC does not produce emulsified binders, we play a key role in the infrastructure that supports their use. Our modular, relocatable Bitutainers™ are designed to handle the technical demands of storing and transferring both emulsified and conventional bitumen, making them a valuable asset for evolving asphalt operations.