03 adam hand

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Presentation delivered by Adam Hand on "Superpave" at the California Asphalt Pavement Association Spring Conference April 25, 2013 in Ontario, CA.

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  • Thank you chairman and organizing committee
  • Sensitivities noted on slide
  • Sensitivities noted on slide
  • 03 adam hand

    1. 1. SuperpaveSuperpaveContractor’s PerspectiveContractor’s PerspectiveCalifornia Asphalt Pavement ConferenceCalifornia Asphalt Pavement ConferenceAdam J.T. Hand, PhD, PEAdam J.T. Hand, PhD, PEOntario, CAOntario, CA April 24, 2013April 24, 2013
    2. 2. Outline ExperiencesAcademic – UNR, WRSC, WT, PurdueIndustry – GCI, Several RolesService – SP ETG, NCHRP, AAPT, NAPA, … Lessons LearnedMaterialsLabs and EquipmentImplementationLab vs. FieldProduction & Construction Context – Superpave and QC/QA All at Once
    3. 3. Lessons Learned Things We Worried About:Aggregate Properties (CAA, FAA, FEP)Mix Design VerificationRestricted Zone PMBs How to Handle RAP Performance Testing Tenderzone
    4. 4. Lessons Learned Asphalt Binder Specification – Chemical GoalPhysical Property Spec - Huge ImprovementStill - PG+, MSCR, PPA, CRM, TB AggregatesNot Big Change in California – Early 1990’sRestricted Zone – GuideARZ, BRZ, TRZ can ALL Perform WellSome Sand May Be NeededWashed Crusher Fines, Chips?P200 Must Be Managed – Mix Sensitivity
    5. 5. ASTM STP December 2000p200 Management - 19mm Example0123456789104.0 5.0 6.0 7.0% AC%AirVoidsAt Target p200 = Solid LinesAt Field Observed p200 = Dashed LinesReduction in ACat 4.0% AV =0.8% due to+1.5% p200Reduction in AVat Opt AC = 1.8%due to +1.5%p200
    6. 6. Lessons Learned Δ from AASHTO Standards = Challenging…NDesignMin VMA (increase vs. production)D/A (smaller NMAS mixes)FEP (3:1)T283 (conditioning and minimums)Adding Conflicting Requirements Use or Generate Data via Shadow Specs First
    7. 7. Everything is Bigger in the Lab Bigger Samples (4x)Bigger EquipmentMore Square Footage$ InvestmentSGC4800gHveem1200g800lbs - Really?
    8. 8. Everything is Bigger in the Lab
    9. 9. Everything is Bigger in the Lab
    10. 10. Compactors and Verification Superpave Center and ETG – SGC’s10 yearsSGCs are NOT all the sameSGC Frame ComplianceInternal Angle Verification NeededDON’T Buy a Headache!!!Follow Your Owner? Superpave Center – Mix VerificationAggregates BatchingDust Correction Will Now Know Source of Δ
    11. 11. Everything is Bigger in the LabHWTD
    12. 12. Hamburg Wheel Track Device (HWTD) Colorado →Texas, … (Rutting and Stripping) Slabs or paired cylindrical samples, 7 ± 2% AV (Cores OK) 8”diam x 1.75” steel wheel, 50pass/min, 158lb load 50ºC and 20k passes or ½” rut depth, SIP 50ºC and PG64 (5k), PG70 (10k), PG76 (20k) ≤ ½” r & R not yet published
    13. 13. AASHTO T324 Hamburg Test MethodILS by AMRLSGC4800gHveem1200g ILS AMRL Prepared all Samples Only Cutting and Test Method Variability9.5mm 19mm
    14. 14. AASHTO T324 Hamburg ILS
    15. 15. AASHTO T324 Hamburg ILSObservations Very Significant Variability in Results Between LabsDid Not Publish Precision Statement Conduct Ruggedness Experiment First Key Factors Affecting Results:Starting location of the wheelWheel track alignment on the sampleNumber of sensors and sensor locationsGyratory sample cutting and mold Closely Inspect your New Equipment Utah DOT Similar Experience – Great Job AddressingBefore Implementation Encourage Similar in California
    16. 16. Dry Tensile Strengths vs. Binder GradeDate of Design AgencyMethod/SampleDiameterLaboratory Who PerformedTestingMix DesignNominalMaximum SizeBinder GradeAggregateSourceAnt-StripMethodDry TensileStrength (psi)3/25/2010 Caltrans Hveem/4” Construction Materials Engineers 12.5mm PG 64-28PM Source ALime SlurryMarination861/31/2012 NDOT Hveem/4” NDOT 19.0mm PG 64-28NV Source ALime SlurryMarination1001/31/2012 NDOT Hveem/4” NDOT 19.0mm PG 64-28NV Source ALime SlurryMarination765/29/2012 FAA Marshall/4” Eastern Sierra Engineering 12.5mm PG 64-28 Source ALime SlurryMarination718/24/12 NDOT Hveem/4” NDOT 19.0mm PG 64-22 Source ALime SlurryMarination12510/1/2012 Caltrans Hveem/4” Construction Materials Engineers 9.5mm PG 64-28TR Source ALime SlurryMarination773/1/2013* Caltrans Hveem/4” Construction Materials Engineers 19.0mm PG 64-28 Source ALime SlurryMarination843/22/2013* Caltrans Superpave/6” GARCO - Stockton 19.0mm PG 64-28 Source ALime SlurryMarination94*- The 3/22/2013 Superpave 6” diameter dry tensile strength data was performed using the same gradation andoptimum asphalt content obtained from the 3/1/2013 Hveem design as to permit a direct comparison of sample size vs.dry tensile strength.
    17. 17. Min Dry Tensile Strength
    18. 18. Dry Tensile Strength = f(PG Binder Grade)Mix TypeAggregateSourceBinderTypeAsphaltContent(BDW)CompactionMethodDryTensileStrength(psi)HamburgRut Depth@ 15,000passes (in)HamburgInflectionPoint (No. ofPasses)¾” HMA Source A PG64-28 5.5 Hveem – 4” 84 n/a n/a¾” HMA Source A PG64-28 5.5 Gyratory– 6” 94 0.1 >25,000¾” HMA Source A PG70-10 5.5 Gyratory– 6” 211 n/a n/a• Dry Tensile Specification > 120 psi• Hamburg Rut Depth < 0.5in after 15,000 passes• Hamburg Inflection point – min. 10,000 passes
    19. 19. Tensile Strength Specimens under Tensile Stress/Strain What Material Can Resist Tension? Key Drivers of Tensile StrengthBondBinder Stiffness Should PG70- 10 vs. PG64-22 vs. PG64-28 all havesame TSDry?Binder Stiffness vs. Grade (1/2 or 2x) NCHRP Report 444, "Compatibility of a Test forMoisture-Included Damage With SuperpaveVolumetric Mix Design“No Difference in Hveem and Superpave TS
    20. 20. Impacts of Lab Turnaround Time Function of:Project Location/LogisticsTest MethodAvailable Resources Test and TimeVolumetrics and In-Place Density ≈ 1-2 daysWTD ≈ 3 daysTSR ≈ 7 days Risk (Production TSR Example)≈ 2000 to 4000 tons/ day x $100/ton in-placeOver $1M per week (2kx$100x7days) – WOW!How to Address Risk?
    21. 21. Plant Production Aggregate Plant Balance? VSI Crushers? RAP Fractionation?Treat Like AggregateAdditional Feed Bins and ControlsDrive with Acceptance Criteria Volumetric SpecificationsSensitivity to p200More Washing?Baghouse Controls? Aggregate BreakdownSGC = Plant?How Addressed?
    22. 22. ASTM STP December 2000p200 Management - 19mm Example0123456789104.0 5.0 6.0 7.0% AC%AirVoidsAt Target p200 = Solid LinesAt Field Observed p200 = Dashed LinesReduction in ACat 4.0% AV =0.8% due to+1.5% p200Reduction in AVat Opt AC = 1.8%due to +1.5%p200
    23. 23. Aggregate Breakdown Mix Design to Post-Plant (Lab to Field) Must Consider in Mix Design Process Production Start-up Gradation Acceptance Does Breakdown in Lab Mixer and SGC =Breakdown in Drum or Dryer and Pugmill?NO What Gradation Should be Used in Mix DesignStockpile, Hot Bin, Coldfeed? What Gradation Should be Used for Acceptance?Coldfeed, Hot Bin, or Post-Plant?
    24. 24. 24What About Production? Lab Mix Design to Field ProductionDifferences are Real – Must Address What Occurs During Production that AffectsGradation and Volumetrics?Breakdown in the Drum (p200 ↑)If p200 ↑ Post Plant what will be Done to Maintain4.0% Air Voids, …?Reduce %AC?Reduced DurabilityIs this Good or Bad?%ACRuttingDurability
    25. 25. Lab Mix Design to Field Production Mix Design Purpose? How to Address Δ’s - What is End Goal? End Product QualityField Adjust AC and Grad to DesiredVolumetricsAppropriate TV Δ’s P200 dosing in MD? Test Strip %AC, Gradation, Volumetrics – Same Sample …
    26. 26. Aggregate Breakdown Example0102030405060708090100PercentPassingSieve Size ^ 0.45 Power (mm)Hot Bin BlendIgnition Oven GradationSpec LimitTarget Values0.0750.150.30 0.60 1.18 2.36 4.75 9.50 12.5 19.0Over 5% on coarse sievesand 2% on p200
    27. 27. Asphalt Binder Set Point Verification (Hot Drop)Plant Set Point = Mix Design OBCIn-Spec – Go to ProductionOut-of-Spec - Repeat, Repeat, Repeat ProductionPlant Setpoint = Mix Design OBCStandard Processif PSP and OBC Δ ≤ 0.4% OKIf PSP and OBC Δ ≥ 0.4% Shut DownQC/QAif PSP and OBC Δ ≥ 0.0% PWL CompomisedTypical σT = 0.20
    28. 28. Lab Mix Design to Field Production Lab to Field No %AC Set Point Change? Impact on Volumetrics Impact on %AC PWL/PFσ%AC = 0.20 typical (CT, AMRL, …)Off Target, no Set Point or TV Δ
    29. 29. %AC Pay Factors forSpec Tolerances = ±0.4%0.750.800.850.900.951.001.050.00 0.10 0.20 0.30 0.40 0.50StandardDeviationPayFactorOffset = 0Offset = 0.1Offset = 0.2Typical Variability1.010.95
    30. 30. %AC Pay Factors forSpec Tolerances = ±0.3%0.750.800.850.900.951.001.050.00 0.10 0.20 0.30 0.40 0.50StandardDeviationPayFactorOffset = 0Offset = 0.1Offset = 0.2Typical Variability0.940.83
    31. 31. Superpave Experiences 2005Stockpile ManagementPre-Superpave
    32. 32. Superpave Experiences -32Stockpile ManagementPost-Superpave
    33. 33. Additional Feeder Bins RAP Fractionation 12 Bins at 1 Hot Plant?
    34. 34. Accurately MeteringBaghouse Fines?
    35. 35. Wasting Baghouse Fines?
    36. 36. Superpave is Technology Friendly Can Technically Address in LabNeat, PMBRAPRASWMA… We Can Field Produce
    37. 37. Field Observations NMAS¾” has ¾” Rock in Itt/NMAS ≥ 3, Max by Density Measurement BRZ can = Segregation (everywhere) & WorkabilityChallenges – Training and QC Critical Density Matters!!!Get All but 1.5% ImmediatelyFewer PneumaticsTenderzone (not something new) Truck Loading Focus MTV’s Joints
    38. 38. Field Observations Have Compacted up to 5.5” Lift with ¾” NMAS We Can Place and Compact Superpave MixesTenderzone - special Kneeding compactors?
    39. 39. Training is Critical to Success!
    40. 40. Training Needs Significant Training Required:Professional and TechnicalMix Designers and TechniciansEstimating StaffPlants StaffConstruction Operations StaffInspection StaffAgency/Contractors/Engineering FirmsConsider FHWA Efforts in Early 1990’s
    41. 41. My Gut Importance of Training Will Be WAY Under Estimated Lab Investment will Be Too Slow - Logistics Issues? Issues with Differences in Caltrans and AASHTO andCity/County Specs – Design, Equipment, Acceptance,Mix Management, … will ExistGrad+D/A Spec, Grad +Vol Independent SamplesHWTD, Dry Tensile Strength, Lab to Field Could Have HWTD Challenges if Not Patient Could Not Address Aggregate Breakdown and MixSensitivity Some Aggregate Sources will Be Challenging Required Plant Investments will Be Underestimated There will Need to Be Specification Iterations
    42. 42. Moving Forward Superpave = HUGE Step ForwardSuperpave = HUGE Step Forward Late Adoption will Eliminates Others Early ChallengesLate Adoption will Eliminates Others Early Challenges InvestmentInvestment LabsLabs Plant $ – VSI’s, RAP Feeder Bins, Baghouse ControlsPlant $ – VSI’s, RAP Feeder Bins, Baghouse Controls Con Ops – No ProblemsCon Ops – No Problems Technology – RAP, RAS, WMA, … friendly - JDITechnology – RAP, RAS, WMA, … friendly - JDI Get Lab Equipment and Methods Right FIRSTGet Lab Equipment and Methods Right FIRST We Will All Need to Continually ImprovementWe Will All Need to Continually Improvement Binder, Mix Design, Perf Tests, Mix to StructuralBinder, Mix Design, Perf Tests, Mix to StructuralDesign, Test Methods and SpecificationsDesign, Test Methods and Specifications We Will Make Better Products and That Will Be Good forWe Will Make Better Products and That Will Be Good forOur IndustryOur Industry
    43. 43. QuestionsQuestions

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