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overview warm mix and high rap mixes in virginia

Overview Warm Mix and High RAP Mixes in Virginia. Trenton M. Clark, P.E.

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overview warm mix and high rap mixes in virginia

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    1. FIRST SLIDEFIRST SLIDE

    3. First introduced to Virginia in 2006 Three initial locations US 211 Rappahannock County US 220 Highland County SR 143 Williamsburg Technologies investigated Sasobit™ Evotherm ET™ WMA – It’s No Longer Your Daddy’s Hot Mix

    4. Developments in 2008 Asphalt plants produced or retrofitted with foaming systems A few contractors ran WMA to private projects in 2008

    5. What Foaming Looks Like

    6. Main Development in 2008 VDOT special provisions for use of WMA in 2009 Permissive specification, not requirement Mix must meet HMA properties for AC content, gradation and volumetrics Minimum TSR value of 60%

    7. TSR Results for 2009 TSR results required from initial production for approval Concerns with moisture in aggregate from foaming process Except for one or two projects, all WMA was from foaming process

    8. TSR Results for 2009 Lowest TSR value – 75% Majority of TSR values – 80% or higher A few results were around 95% To improve TSR, slight increase in anti-strip was added

    9. What is Approved? (List #66) Sasobit – Blown in pellets Evotherm ET Evotherm 3G Astec Double Barrel Green Maxam Aqua Black System Gencor Ultrafoam Gx StanSteel Accu-Shear

    10. How to Get on the List Not a rubber stamp process Independent, documented results required

    11. How to Get on the List Request made from contractor to VDOT Submittal of process/product information Submittal of JMF for process/product Production and placement of test section (500 ton max) Submittal of production lab data Submittal of placement field density data VDOT review and approval, review and rejection, or review and re-submittal

    12. WMA Processes added in 2009

    13. JMF Development and Submittals Foaming Process Normal JMF Process Additional JM Number not required, note added to weigh ticket for inspector information Additive Process “Virgin” mix design at design AC content Additive mix design at “virgin” design AC Additive mix design must meet Section 211 AC content, gradation and volumetric requirements New JM Number assigned to additive WMA Foaming and Additive Processes can be done together following Additive Approval process

    14. Temperatures

    15. Which Side is the WMA?

    16. High RAP Mixes By Spec, maximum amount is 30% in SM and IM; 35% in BM Used to replace virgin binder, replace virgin aggregate, and increase mix binder grade

    17. RAP Processing

    18. Binder Bump Allowed when RAP exceeds 20% of mix PG 64-22 may be used in lieu of PG 70-22 when: Mathematical calculation results in PG 70-16 Monitoring performed during production to validate

    19. Not All PG 64’s are Alike

    20. 2009 Testing Summary 90 RAP Mix Samples tested Most included 20% or more RAP 41 of 90 samples did not meet Table 211.01 requirements Failure rate very high, function of RAP percentage and virgin asphalt binder

    21. Abson Results Through November 2009 Factors Influencing the Top End PG Suppliers Top End (64 through 68) Age and Source of RAP Amount of RAP Percentage of Fine and Coarse RAP used

    22. Changes for 2010 High RAP mixes must meet mathematical blend for JM approval BOL from Binder Supplier must include continuous grade Changes in Binder Source requires new TL-127 coversheet No change in aggregates/RAP, then continue production Changes in aggregates/RAP may require return to Part B stage in JM approval (typically softer virgin binders)

    23. Monitoring High RAP Mixes Research done on using high temperature indirect tensile strength (HT IDT) Testing done on Marshall Press using 6” gyratory pill at 61 C Establish relationship between PG 70 and IDT strength

    24. VDOT Testing Done to Date 24 mixes tested the winter Varying amounts of RAP Each mix was tested for VMA, VTM, VFA, AC%, and gradation

    25. HT IDT Results

    26. Conclusions and Next Steps No relationship between volumetrics and strength No relationship between #200 sieve and strength 300 kPa may be logical breakpoint based on stability testing VDOT will continue testing in early spring with extracting binder and grading to develop relationship

    27. What This Means If successful, screening tool for new mixes Monitoring tool for contractor during production Monitoring tool for VDOT during production Reduce number of mixes extracted and graded by CO-Asphalt Lab

    28. Overview Warm Mix and High RAP Mixes in Virginia

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