Lowering the manufacturing temperature opens up new opportunities for asphalt as a construction material. Lower energy costs and less emissions are only part of the positive characteristics of low-temperature asphalt.

Despite the growing number of varied solutions that have appeared on the market we believe that it is not enough to focus exclusively on a particular method of introducing additives or foam bitumen. The entire process chain is affected, starting with drying at a reduced temperature through to specific mixing sequences and on to the introduction of recycling. Ammann has focused their research and development on the complete manufacturing process for low-temperature asphalt with an injection device being simply the beginning.


Ammann does not focus on a particular method of introducing additives or foam bitumen because many more variables must be considered. The entire process chain is affected, starting with drying at a reduced temperature, continuing through to specific mixing sequences and including the introduction of recycled materials.


  • Lower manufacturing costs
  • A safer working environment for road crews
  • Reduced emissions at the jobsite
  • Lower emission of CO₂ at the plant
  • No need for new paving equipment; the same pavers and rollers are used


Foamed asphalt meets the quality requirements for hot-mix aggregate. The asphalt specifications and the paved layer remain the same. By observing the recommended procedures, the same laboratory tests and processes can be used.

Many countries are now working on national projects aimed at incorporating low-temperature asphalt into the standards. Until they have been adopted, it is important to verify that work tenders explicitly state that use of low-temperature asphalt is permitted.

Low-temperature asphalt production is perfectly compatible with the use of reclaimed asphalt, because the lower mixing temperatures cause less oxidation of the bitumen contained in the RA. Since there is also less aging of the fresh bitumen during the mixing process, improved low-temperature behaviour can be expected from the blacktop.

Foamed bitumen is also used to aid paving in certain countries because it can increase the compactability of the asphalt.


  • Same product quality as hot asphalt
  • Same recipes as those used for hot asphalt
  • Same user guidelines as for hot asphalt
  • Same testing procedures
  • Fewer emissions on the jobsite
  • Lower C0₂ emissions at plant
  • Significantly less fuel consumption



The differences between warm and traditional mixes become apparent during placement of the asphalt.

The paving and compaction process changes depending on the low - temperature technology applied. For example, the foam - based mix is compactable for a longer period, while wax - based mixes harden quickly.

Conditions for paving crews are improved, with significantly reduced bitumen vapours and odours. A reduction in the asphalt temperature by 10° C typically cuts in half the emissions on a construction site. This means that a 50° C reduction reduces the emissions by around 95 per cent.


  • Same product quality as hot asphalt
  • Lower emissions at the construction site
  • Lower emission of CO₂ at the plant
  • No need for new paving equipment; the same pavers and rollers are used


Ammann is convinced that the future lies with low temperature asphalt. In cooperation with customers and laboratories, we have developed the Ammann Foam process.

This process is based on the foaming of bitumen with water and is employed in continuous and batch plants. Ammann Foam works without any chemical additives and also can be retrofitted to existing plants with minimal effort.

The process begins when hot bitumen is pumped into the foam generator. Cold water with no chemical additive is injected under high pressure and mixed with the hot bitumen. This water/bitumen mix is then forced through the outlet. The water expands when the mix leaves the foam generator, and the so -called foam bitumen is created.


  • Heating of the raw aggregate to approximately 115 ° C
  • Perfect mix of bitumen and aggregates
  • Asphalt compaction at low temperatures
  • Foam generator can be integrated into continuous and batch plants
  • Retrofitting to existing plants is possible


 A foam bitumen installation enables expansion of your plant’s product portfolio. The foam generator from Ammann enables the foaming of various hardnesses of road construction bitumen and also polymer-modified bitumen.

The foam generator also can be used to manufacture cold base courses with 100 per cent recycled materials. This means that the use of foam bitumen optimally supplements the recycling feed in the mixer.


In the first phase of mixing, the rough granular aggregate is placed in the mixer. The foamed bitumen is introduced into the twin-shaft paddle mixer through the nozzle so that it also coats the rough granular aggregate at about 100° C. The remaining aggregate and filler is then introduced into the mixer.


The foamed bitumen is introduced into the mixer together with the aggregate at a temperature of about 100° C. The intensive mixing action of the twin-shaft paddle mixer, which operates continuously, ensures excellent coating of all granular aggregate.

The foamed bitumen is fed into the mixer initially by means of injection nozzles

Exterior view: Mixer equipped with a foam generator


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