Most questions related to maintaining a suitable temperature during the mixture’s manufacture have been regulated by commonly known technical specifications (e. g., standards, guidelines). These questions are discussed in Chapter 9. Simply speaking, there are two main problematic instances in the matter of SMA manufacture temperatures—when the temperatures are too low or when the temperatures are too high.
Too low a manufacturing temperature of a mix prevents the formation of a correct and complete asphalt binder film. Too low a temperature can be visually recognized; aside from visible uncoated aggregate pieces, the appearance of the mixture seems to be matte. Since SMA contains a considerable amount of binder, it should be glossy and glisten “glow wormly” (namely, like glow worms) at a suitable temperature.[69] Too high a manufacturing temperature increases the threat of binder draindown from the aggregate and excessive aging of the binder. Loading the overheated SMA into a silo runs the risk of getting into trouble with excessive draindown. To check SMA susceptibility to draindown after mixture overheating, one ought to test it when the SMA is at a temperature 15°C (or 25°C) higher than the recommended manufacture temperature (see Chapter 8).
