What is Foam Bitumen?

Foam Bitumen is produced by foaming standard bitumen grade C170. The process consists of adding small amounts of water usually 2 to 3% by mass of the bitumen. The water is injected in conjunction with air to hot bitumen, which has been heated to between 170 and 180 degrees Celsius. When injecting the water at high pressure the water evaporates instantaneously forming a bubble surrounded by oil, this causes the bitumen to expand to around 20 times its original volume.

This increased volume results in a reduction of the viscosity of the bitumen. The bitumen foam is then injected into a mixer via injection nozzles which is then eminently suitable for mixing with cold and moist construction materials. This process creates a visco-elastic material which once it is compacted it is strong, moisture resistant, flexible, non-temperature sensitive and durable. Foamed bitumen is a unique pavement treatment for treating new materials or rehabilitating existing pavements that have exceeded their serviceable life. 

 

This is how Foamed Bitumen is produced in the Laboratory

The main benifits of foam bitumen.

  • More cost effective than other forms of bitumen stabilising agents.
  • Conserves aggregate resources.
  • Results in a strong durable and flexible pavement layer.
  • Has success of rehabilitating historically troublesome sections of pavements.
  • It has an affinity to most natural gravels and crushed rock aggregates.
  • Minimises inconvenience to road users, due to the speed and efficiency of the process.
  • Significantly reduces or eliminates excavation volumes and the requirement to import pavement materials.
  • Reduction in basecourse thickness resulting in reduction in premium basecourse aggregates.
  • The compacted and finished layer can be trafficked almost immediately.