Rapid curing and strength build up are required in these applications as traffic is allowed on immediately. They differ from storable asphalt mixes in two essential parameters :
- Lack of fluxing agent in the dispersed phase of the emulsion and therefore limited storability.
- Mineral aggregate gradation giving low void content
Asphalt concretes with bitumen emulsions are the subject of many proprietary processes to primarily give a complete coating of the mineral aggregate granular fraction and improving their workability:
- Sequenced coating
- Double coating using two different emulsions
- Hot coating of the sand fraction
- Heating of asphalt concrete mixture
Because of their end purpose, asphalt concretes with bitumen emulsions are applied by the conventional paver and are suitably roller compacted. Commonly applied layer thicknesses vary between 3 and 6 cm.
The initial void content of asphalt concretes with bitumen emulsion is below 15%; after installation, the void content reduces further under traffic giving a further improvement of the mechanical performance of the asphalt mixture. Reduction of the void contents may be up to 5 points after compaction.