What You Should Know About Foam Bitumen

9 October 2019
 Categories: , Blog

Foam bitumen is a critical element in pavement stabilisation. You can trace the utility of foam bitumen back to 1956. The foam bitumen design allows it to be useful in recycling projects as well as highway stabilisation projects. This technology is also necessary for the construction of airport pavement. Here is all you should know about foam bitumen as well as foam bitumen stabilisation.

Defining foamed bitumen

You can produce foamed bitumen by mixing water with hot bitumen. After injecting the hot asphalt to the water, it will instantly evaporate and form air bubbles. This action makes the bitumen to expand and foam by more than 30 times its initial size. This expanded volume causes viscosity reduction that enables the mixing of bitumen with damp, cold materials.

The process

Foamed bitumen flows from the expansion chamber via a nozzle. Merging it with aggregates in the mixing and milling chamber is the next step. Rollers, graders and water tankers will then moisten, compact and finish the stabilised layer.

In respect to weather conditions, the stabilised layer will cure after 24 to 36 hours before the sprayed seal application. In areas where higher traffic is necessary, the sprayed seal will have asphalt surfacing application after the evaporation of the diluents.

When you should consider a foam bitumen application?

Some of the situations that indicate the need for a foamed bitumen application include;

  • When your pavement has a myriad of patches that more repair will not be efficient
  • If there is overloading and you can no longer control it easily
  • When your asphalt overlays can longer solve flushing issues

Benefits of foamed bitumen

  • The use of a foamed asphalt solution saves time in construction since you can compact it and instantly carry traffic.
  • The change in weather conditions, like cold weather or slight rain, will not affect the performance and quality of the foamed asphalt. You can construct layers of foamed asphalt in all weather conditions.
  • You can use foamed bitumen with various kinds of aggregates. Mostly, mixing small diameter aggregates with bitumen is an ideal option.
  • Preservation of energy: asphalt is the only component that needs heat. You can mix the bitumen and aggregate when they are wet.


In regards to the aggregate, the ideal temperature for mixing aggregate with foamed bitumen is between 13 degrees Celsius and 23 degrees Celsius. The primary functions of the foamed bitumen application are to reduce the susceptibility of muscles and boost resistance to fatigue. Therefore, they are ideal for engineering purposes.