The Superpave mix design method consists of 7 basic steps:
Moisture susceptibility is a primary cause of distress in HMA pavements. HMA should not degrade substantially from moisture penetration into the mix. HMA mixtures may be considered susceptible to moisture if the internal bitumen binder-to-aggregate bond weakens in the presence of water. This weakening, if severe enough, can result in stripping.
To measure the potential for moisture damage to HMA mixtures, moisture susceptibility testing can be performed. Results from the moisture susceptibility test may be used to predict the potential for long-term stripping and to evaluate anti-stripping additives, which are added to the asphalt binder, aggregate, or HMA mixture to help prevent stripping.