Bitumen is a crucial ingredient in asphalt for constructing roads, pavements and other items for transport. Bitumen is used as a binder in road construction and in protective coatings and adhesives used in the construction industry.

In the most common processes, the bitumen is heated to 100–200° C until fluid enough to mix with aggregate. The ‘hot mixed’ materials must themselves be stored, transported and used hot to maintain their workability.

Bitumen emulsion is a mixture of water & bitumen provides an alternative approach in which the bitumen is liquefied by dispersing in water. Emulsifier can be defined as a surface-active agent. Emulsifier keeps the bitumen in its fine droplet state by disallowing it to mix with other droplets. Therefore, we can say that a bitumen emulsion is a liquid product consisting of three things, (i.e. water + Emulsion + Bitumen) where droplets of bitumen are suspended in water.

Types of Bitumen Emulsion:

There are two different ways to classify bitumen, as given below.

1. Based on surface charge
2. Based on setting time

Based on Surface Charge

Depending upon the type of surface charge, bitumen emulsions are primarily classified into the following two types.

1. Anionic Bitumen Emulsion
2. Cationic Bitumen Emulsion

Based on Setting Time

Depending upon the speed at which water evaporates and bitumen particles separate from water, it is classified into following 3 types.

1. Rapid Setting Emulsion (RS)
2. Medium Setting Emulsion (MS)
3. Slow Setting Emulsion (SS)

What Are the Uses of Bitumen Emulsions?

1. Emulsions are used in bituminous road construction work. They are especially helpful for maintenance and patch repair works.
2. Emulsion can be used in wet weather even when it is raining.
3. Also, emulsions have been used in soil stabilization, particularly for stabilization of sands in desert areas.
4. A rapid setting type emulsion is suitable for surface dressing and penetration macadam type of construction.
5. Medium setting type is used for premixing with coarse aggregates.
6. In case of fine aggregates, the surface area of aggregate is more and as a result long duration of time is required to mix the emulsion. Therefore, slow setting emulsion is preferred which gives sufficient time for uniform blending of the mix.