The objectives of this research were to (1) recommend revisions to the SUPERPAVE gyratory compaction procedure (AASHTO T 312) and related mixture preparation requirements, and (2) recommend SUPERPAVE gyratory compaction procedure(s) for SMA, open-graded, gap-graded, and large stone mixtures.

The key product of the project was a recommendation soundly supported by experimental results to reduce the number of possible design gyration values in AASHTO PP28 (now AASHTO M 323) to 4 from the original 28. This recommendation was accepted by the FHWA Mixture Expert Task Group and referred to the AASHTO Lead States Team and Highway Subcommittee on Materials; it has been incorporated in the standard.

An executive summary of the final report was published as NCHRP Research Results Digest 237. The entire three-volume final report is available on the CD-ROM titled CRP-CD-1: Bituminous Materials Research Series.