6. Fluidified and fluxed bitumens

Pure bitumens are highly viscous products which require special treatment before they can be used. The simplest method is to heat bitumen to a temperature corresponding to its softening point, plus approximately 100°C. This technique is commonly used for the preparation of hot bituminous mixes, the primary outlet for bitumen production, but it requires heating and dehydration of the aggregates.

On the other hand, the use of a binder to produce a surface dressing or cold mix, whatever its precise nature, requires a level of viscosity compatible with spraying or coating. Viscosity is reduced by adding a fluidizer (volatile solvent) or a fluxing agent (low-volatility oil). Once the material has been applied to the pavement, partial evaporation and absorption of the additive lead to a gradual return to the characteristics of bitumen, as soon as the structure is put...