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Specification Summary. Where we’ve Been & Where we are Now (A Review of Past & Present Specifications). By: John Garrity Dave Holt, and Ron Bumann. Bituminous Specification Timeline. Specification 2331 (Pre 1988) Specification 2340 (1988) Specification 2340 Modified (1997)
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Specification Summary Where we’ve Been & Where we are Now (A Review of Past & Present Specifications) By: John Garrity Dave Holt, and Ron Bumann
Bituminous Specification Timeline • Specification 2331 (Pre 1988) • Specification 2340 (1988) • Specification 2340 Modified (1997) • Specification 2350 (1998) • Specification 2360 (1998) • Combined 2350/2360 (2003)
2331 • MnDOT Standard Specification Before 1988. • Agency Designed Mixes for Contractor. • Process Control and Acceptance by Agency: Asphalt Spotchecks Aggregate Gradations • Contractor Role To Produce and Place Mix
Specification 2340 • Implemented in 1988 as a Quality Management Specification. • Address problems associated with rutting and flushing and raveling. • Contractor Involvement • Mix Design • Process Control Testing (QC) • Mixture Acceptance • Air voids used as primary acceptance criteria
Specification 2340 Modified • Implemented 1997 • Enhancement to 2340 • New Mixture Quality Measures • Voids in Mineral Aggregate (VMA) • Moisture Susceptibility (TSR)
Specification 2350 • Implemented in 1998 as replacement for 2331 and 2340 (Marshall Design). • Complete re-write of 2331 and 2340. • Changed mixture designations • Included VMA, TSR, F/A • Increased Density Requirements • Included Ride Requirement • Removed methodology of 2331 and 2340 • Included Incentives/Disincentives. • Move toward end result specification. • In 1998, required on all MnDOT projects with traffic < 3 million ESAL’s.
Specification 2360 • Implemented in 1998 as Superpave specification and a companion specification to 2350. • Same requirements as 2350 including additional aggregate requirements. • Included Incentives/Disincentives. • Move toward end result specification. • In 1998, required on all MnDOT projects with traffic > 3 million ESAL’s.
2360Combined 2360/2350 (Gyratory/Marshall Design) Specification • Implemented in 2003 as a new stand-alone specification. Includes both Marshall and Gyratory (Superpave) design. • Current MnDOT specification selection criteria: • Gyratory Design • All new construction and mid and long life overlays. • Marshall Design • Short life overlays (<5 years) and/or small quantities (<5,000 tons).
Responsibility Levels Through Specification Evolution 2331 2340 2350 2360 Mix Design Agency Contractor Contractor Contractor Plant Prod/Control Agency Contractor Contractor Contractor Field Compaction Agency Agncy/ Cont. Contractor Contractor (Density)
Specification Evolution is a result of... • Agency & Industry Initiative • Asphalt Pavement Performance Steering Committee • MnDOT, FHWA, Industry, and Local Government • Specification Technical Working Group