The document discusses the development of the Superpave asphalt pavement mix design system. It describes how the Strategic Highway Research Program from 1989-1993 invested $150 million, including $50 million to improve asphalt mix design. The Superpave system introduced a two-level mix design approach involving volumetric mix design specifications at Level 1 and performance testing of rutting, fatigue, and low-temperature cracking at Level 2. Over time, revisions have been made to reduce compaction levels, allow for increased reclaimed asphalt, and incorporate warm mix asphalt and additional performance tests.
2. Superior Performing Asphalt Pavement
Product of SHRP –
●Strategic Highway Research Program
1989 – 1993
$150 Million
$50 Million on ASPHALT!
9. Observations with implementation
●Reduce Ndesign for base mixes
●Reduce the number of traffic levels
●Ndesign yielding low binder contents
●Constructability problematic
●Reduce Ndesign for low volume roads
10. ESAL
(106) Ninitial Ndesign Nmax
< 0.3 6 50 75
0.3 to <3 7 75 115
3 to <30 8 100 160
≥30 9 125 205
Based on independent work by NCAT and Asphalt Institute
4 Compaction Levels!
12. RAP and RAS
●Increased use in recent years (no
provisions for using RAP in original
Superpave mix designs)
Moisture Sensitivity
●Still AASHTO T283
●Greater reliance on other tests –
Hamburg Wheel Tracking Test