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2015 APAM Conference Hot Mix Asphalt (HMA) Update

2015 APAM Conference Hot Mix Asphalt (HMA) Update. Kevin Kennedy HMA Operations Engineer Michigan Department of Transportation 4-22-15. Hot Mix Asphalt (HMA) Update. Acceptance of HMA on Local Agency Projects HMA Quality Improvements

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2015 APAM Conference Hot Mix Asphalt (HMA) Update

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  1. 2015 APAM Conference Hot Mix Asphalt (HMA) Update Kevin Kennedy HMA Operations Engineer Michigan Department of Transportation 4-22-15

  2. Hot Mix Asphalt (HMA) Update • Acceptance of HMA on Local Agency Projects • HMA Quality Improvements • Portable Plants and Utilizing Recycled Asphalt Pavement (RAP) from the same project • Recycled Tire Rubber Permissive Specification • Miscellaneous Specification Changes • HMA Production Manual • National Peer Review

  3. Acceptance of HMA on Local Agency Projects • New Specification Approved • Immediate Use- NHS Routes and Routes Chosen by Local Agency • Full Implementation October 2015 • Interim- Old Specification With Minor Revisions or New Specification • Covers Roller Method and Density Testing with Nuclear Gauge • Revises Tolerance Limits and Penalty Structure for HMA Mixtures • Strengthens Sampling and Testing Requirements • Adds Time Frame for Reporting Quality Assurance Test Results

  4. Local Agency- Tolerance LimitsTable 1 – Uniformity Tolerance Limits for HMA

  5. Acceptance of HMA on Local Agency Projects Sampling and Testing Requirements • All persons performing testing must be Bituminous (Bit) Level One certified or Bit Quality Assurance/Quality Control (QA/QC) Technician certified. • All laboratories performing local acceptance testing must be qualified laboratories. • Qualified per the HMA Production Manual and participate in the MDOT Round Robin process • or Laboratory must be AASHTO Materials Reference Laboratory (AMRL) accredited for AASHTO T 30 or T 27, and AASHTO T 164 or T 308. • Contractor Laboratories: • Non-NHS: Allowed • NHS: Not Allowed

  6. Acceptance of HMA on Local Agency Projects Sampling and Testing Requirements • Qualified Samplers Required • Qualifying of Samplers to be handled by Ferris State University • MTM 313 (Sampling HMA Paving Mixtures) • MTM 324 (Sampling HMA Paving Mixtures Behind the Paver) • Minimum – Obtain and test two samples per day • No longer testing at frequency determined by engineer • Quality Assurance Test Results – Time Requirement • 7 days – projects more than 5000 tons • 14 days – projects less than 5000 tons

  7. Acceptance of HMA on Local Agency Projects Penalty Structure Table 3: Penalty Per Parameter Out of specification- 2 consecutive tests outside of range 1 or range 2

  8. Acceptance of HMA on Local Agency Projects Density Testing • Two Options • Direct Density Method • Nuclear density gauge • 92-98 percent of density control target (Gmm from JMF) • Roller Method • Added table for Minimum Number of Rollers Recommended Based on Placement Rate • Added table for Density Frequency Curve Development. • Timing • During paving operations • Prior to traffic staging changes • Prior to subsequent lifts and opening to traffic

  9. Acceptance of HMA on Local Agency Projects Additional Significant Changes • Regress air voids in production to 3.5% • Dispute Process • Range 1- Independent Laboratory • Range 2- Construction Field Services HMA laboratory (MDOT Central Laboratory)

  10. Acceptance of HMA on Local Agency Projects Future Changes • Move towards volumetric testing • Air Voids, VMA, ?? • Doesn’t Necessarily Mean SuperPave • Sampling Behind the Paver/Mini-Stockpile

  11. HMA Quality Improvements • Regress Mixes to 3% Air Voids • Requiring Fine-Graded or Gap-Graded for Top Courses • Ride Quality Incentive

  12. Quality –Regress High Volume Mixes • Regress Mixes to 3% Air Voids in Production for E10, E30 and E50 Mixes • Effective October Letting Table 3- For mixtures meeting the definition for top and leveling courses: Mixtures must be designed to 96.0% of Maximum Specific Gravity (%Gmm) at the design number of gyrations, (Nd). During field production Percent of Maximum Specific Gravity (%Gmm) at the design number of gyrations, (Nd) will be increased to 97.0% for E10, E30, & E50 mixes. For all other mixes, Percent of Maximum Specific Gravity (%Gmm) at the design number of gyrations, (Nd) will be increased to 96.5% during field production.

  13. Quality - Regress All Mixes • Regress Mixes to 3% Air Voids in Production For All Mixes • Effective March Letting Unless noted otherwise on the plans, all mixtures must be designed to 96.0% of Maximum Specific Gravity (%Gmm) at the design number of gyrations, (Nd). During field production Percent of Maximum Specific Gravity (%Gmm) at the design number of gyrations, (Nd) will be increased to 97.0%.

  14. Quality - Regress All Mixes • Additional Changes • Changing the upper air voids limit on single test acceptance (changed to 2.0 from 2.5) • Changing suspension limits in Table 4 for binder content (changed from 1.00 to 0.75) • Changing the sublot Rejectable Quality Limits (RQL) for air voids (changed to +2, -1.5 from +2,-2) • Adding removal limits for lots on one course overlays (501V)

  15. Quality - Regress All Mixes Table 4

  16. Quality –Fine Graded/Gap Graded on Top Course • Changed Gradation to Eliminate Coarse Graded Mixes • Eliminated Restricted Zone • FUSP 902E • Effective January Letting • Revises Table 902-5 and 902-6

  17. Quality – Fine Graded/Gap Graded on Top Course

  18. Quality –Fine Graded/Gap Graded on Top Course

  19. Quality – Ride Quality Incentive • Specification Approved (12RC501-A435) • Incentive Starts at IRI of 45 • Increases to $.50 per square yard at IRI of 25 • Applies to High Speed Roads (50 MPH) • Class I and Class II Roads per Ride Quality Specification

  20. Portable Plants- RAP Stockpile Requirements. Process RAP to the size required for the specified HMA mix. Ensure the stockpile contains enough material to produce the recycled mixtures the Engineer approves for the project. If the RAP stockpile is not sufficient to produce recycled mix quantities required for the project, provide an Engineer-approved mix design without RAP at the same unit price.

  21. Requirements for Utilizing RAP Millings from the Same Project When Using a Portable Plant Sampling • Samples to be taken a minimum of every mile in each lane by milling or coring. • Sample areas to be repaired. • Shoulder samples should also be taken if RAP from shoulder is to be used. • Samples should also be taken if visual observations show significant variations in existing mat. • Sampling required for the percentage/tonnage of RAP that will be utilized on the project.

  22. Requirements for Utilizing RAP Millings from the Same Project When Using a Portable Plant Mix Design • A sufficient amount of millings or cores shall be taken at each test location to ensure an adequate amount of RAP is obtained to perform a full mix design. • No paving shall occur using RAP from the project until a mix design is approved.

  23. Requirements for Utilizing RAP Millings from the Same Project When Using a Portable Plant Processing RAP • It is not required to have a stockpile with enough material to produce the recycled mixtures approved for the project. • RAP should be stockpiled* and tested according to existing requirements (one test per 1000 tons, minimum of 3 tests). • If the millings have aggregates larger than what it is required for the mix design, it should be processed (crushed and/or screened) prior to stockpiling*. If aggregates larger than what is required for mix design still exist after processing, the contractor must demonstrate that additional screens are installed on the RAP feed system to ensure that the RAP being introduced into the HMA Mixture contains no aggregate larger than the top size aggregate allowed in the mix design.

  24. Requirements for Utilizing RAP Millings from the Same Project When Using a Portable Plant Processing RAP • In addition, a RAP scalper screen is required**. The top size of the top scalping screen shall be 1.5” for top and leveling courses and 2” for base courses. *If approved by the engineer, in-line crushing and/or screening will be allowed in lieu of processing RAP into a stockpile. The contractor must demonstrate that additional screens are installed on the RAP feed system to ensure that the RAP being introduced into the HMA Mixture contains no aggregate larger than the top size aggregate allowed in the mix design. **If in line crushing and/or screening is being used a RAP scalper screen may not be required.

  25. Recycled Tire Rubber • Grand Region Pilot Project – 2013 • M-57 from East of Northland Drive to West of Morgan Mills Avenue • Crumb rubber portion approximately 3.2 miles on M-57 between Wabasis Road and Morgan Mills • Allowed Wet Process or Terminal Blend (contractor’s option) • Three binders (64-22, 70-22P, 70-22 crumb rubber modified) • 6,007 tons HMA 5E3 Crumb Rubber Modified • Bids • Low Bidder- $79.45 vs $85.83 • 2nd Bidder- $71.15 vs $102.97

  26. MDOT Pilot Project

  27. Recycled Tire Rubber • HMA Tech Committee Directed to Develop Permissive Specification • Originally- specification to mirror pilot project • Concern over reports of poor performance (Waverly Road, Haslett Road, various Saginaw County projects) • PG Binder performance tests have been modified or waived • HMA Technical Committee believes revised tests do not accurately predict performance • No deviations to acceptance test methods/procedures allowed.

  28. Waverly Road 2011 Construction County Road (Photo taken in 2013)

  29. Miscellaneous Specification Changes • FUSP 501G (RAP/RAS)- Added language referring to production manual for blending charts: • When incorporating RAS the asphalt binder grade will be selected using a blending chart for high and low temperatures. • The Contractor must supply the blending chart used in determining the binder selection according to AASHTO M 323 and the HMA Production Manual. • FUSP 501L (Temp Pavement) - Added language clarifying removal of temporary pavement is not part of temporary pavement pay item

  30. Miscellaneous Specification Changes • Gap-Graded SuperPave-  New specification for ½” nominal mix and 3/8” nominal mix • FUSP 504C (HMA ultra-thin overlay)- New specification , no longer Marshall mix.  Includes mix design submittal requirements • HMA Binders- Changes coming to Price Adjustment and Certification procedures • Non-Tracking Bond Coat (Trackless Tack)

  31. HMA Production Manual • Bureau of Highway Instructional Memorandum 14-12 • Includes blending chart instructions for RAP/RAS.  • RAP now part of mix design submittal. • Section 4 was removed from the MDOT HMA Production Manual and added to Section 5.03.01 of the MDOT Materials Quality Assurance Procedures Manual (MDOT MQAPM).

  32. National Peer Review • NCAT/NAPA/FHWA • Construction Best Practices • Bond Coat • Minimizing segregation • Longitudinal Joint Construction • RAP/RAS – Are we doing it right? • Local Agency Acceptance (present and future) • Mix Design • Aggregate/RAP specific gravity • Fine graded mixes

  33. Questions? Kevin Kennedy HMA Operations Engineer kennedyk@michigan.gov 517-322-6043

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