Superpave
Superpave procedure is considered as an improved method for producing a superior performing asphaltic paving mix. It is a short name for Superior Performing Asphalt Pavement.
It was originally developed in 1987 by the Strategic Highway Research Program (SHRP)
In this method of asphalt mix design, the specifications is considered as a performance based unlike empirical as in Marshall method.
Benefits of this type of design: This mix design is to select and proportion the mix materials to get an economical blend of a paving mix , having certain desired properties over the service life of the pavement:
These desired properties include :
- Sufficient strength to resist traffic loading without permanent deformation.
- Sufficient flexibility to resist fatigue cracking.
- good workability to enable proper lay down and compaction.
- Water resistive. Did not disintegrate or strip due to adverse effect of water.
- Durable . To have the original good properties over the service life without unacceptable aging or water induced damages.
- Enough surface friction properties to resist skid.
Superpave mixes are identified as Type SP-9.5, Type SP-12.5 or Type SP-19.0.
The requirements for Type SP Asphalt Concrete mixtures are based on the design traffic level of the project, expressed in 18,000 pound Equivalent Single Axle Loads (ESAL’s). The five traffic levels are as shown in Table
The equivalent AASHTO nominal maximum aggregate size Superpave mixes are as follows: Type SP-9.5..................... 9.5 mm
Type SP-12.5................... 12.5 mm
Type SP-19.0................... 19.0 mm