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

1. SuperpaveSuperpave
Contractor’s PerspectiveContractor’s Perspective
California Asphalt Pavement ConferenceCalifornia Asphalt Pavement Conference
Adam J.T. Hand, PhD, PEAdam J.T. Hand, PhD, PE
Ontario, CAOntario, CA April 24, 2013April 24, 2013

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. Lessons Learned
 Things We Worried About:
Aggregate Properties (CAA, FAA, FEP)
Mix Design VerificationRestricted Zone
 PMBs
 How to Handle RAP
 Performance Testing
 Tenderzone

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. ASTM STP December 2000
p200 Management - 19mm Example
0
1
2
3
4
5
6
7
8
9
10
4.0 5.0 6.0 7.0
% AC
%AirVoids
At Target p200 = Solid Lines
At Field Observed p200 = Dashed Lines
Reduction in AC
at 4.0% AV =
0.8% due to
+1.5% p200
Reduction in AV
at Opt AC = 1.8%
due to +1.5%
p200

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. Everything is Bigger in the Lab
 Bigger Samples (4x)
Bigger Equipment
More Square Footage
$ Investment
SGC
4800g
Hveem
1200g800lbs - Really?

8. Everything is Bigger in the Lab

9. Everything is Bigger in the Lab

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. Everything is Bigger in the Lab
HWTD

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. AASHTO T324 Hamburg Test Method
ILS by AMRL
SGC
4800g
Hveem
1200g
 ILS
 AMRL Prepared all Samples
 Only Cutting and Test Method Variability
9.5mm 19mm

14. AASHTO T324 Hamburg ILS

15. AASHTO T324 Hamburg ILS
Observations
 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 Addressing
Before Implementation
 Encourage Similar in California

16. Dry Tensile Strengths vs. Binder Grade
Date of Design Agency
Method/Sample
Diameter
Laboratory Who Performed
Testing
Mix Design
Nominal
Maximum Size
Binder Grade
Aggregate
Source
Ant-Strip
Method
Dry Tensile
Strength (psi)
3/25/2010 Caltrans Hveem/4” Construction Materials Engineers 12.5mm PG 64-28PM Source A
Lime Slurry
Marination
86
1/31/2012 NDOT Hveem/4” NDOT 19.0mm PG 64-28NV Source A
Lime Slurry
Marination
100
1/31/2012 NDOT Hveem/4” NDOT 19.0mm PG 64-28NV Source A
Lime Slurry
Marination
76
5/29/2012 FAA Marshall/4” Eastern Sierra Engineering 12.5mm PG 64-28 Source A
Lime Slurry
Marination
71
8/24/12 NDOT Hveem/4” NDOT 19.0mm PG 64-22 Source A
Lime Slurry
Marination
125
10/1/2012 Caltrans Hveem/4” Construction Materials Engineers 9.5mm PG 64-28TR Source A
Lime Slurry
Marination
77
3/1/2013* Caltrans Hveem/4” Construction Materials Engineers 19.0mm PG 64-28 Source A
Lime Slurry
Marination
84
3/22/2013* Caltrans Superpave/6” GARCO - Stockton 19.0mm PG 64-28 Source A
Lime Slurry
Marination
94
*- The 3/22/2013 Superpave 6” diameter dry tensile strength data was performed using the same gradation and
optimum asphalt content obtained from the 3/1/2013 Hveem design as to permit a direct comparison of sample size vs.
dry tensile strength.

17. Min Dry Tensile Strength

18. Dry Tensile Strength = f(PG Binder Grade)
Mix Type
Aggregate
Source
Binder
Type
Asphalt
Content
(BDW)
Compaction
Method
Dry
Tensile
Strength
(psi)
Hamburg
Rut Depth
@ 15,000
passes (in)
Hamburg
Inflection
Point (No. of
Passes)
¾” HMA Source A PG64-28 5.5 Hveem – 4” 84 n/a n/a
¾” HMA Source A PG64-28 5.5 Gyratory– 6” 94 0.1 >25,000
¾” 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. 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 have
same TSDry?
Binder Stiffness vs. Grade (1/2 or 2x)
 NCHRP Report 444, "Compatibility of a Test for
Moisture-Included Damage With Superpave
Volumetric Mix Design“
No Difference in Hveem and Superpave TS

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. 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. ASTM STP December 2000
p200 Management - 19mm Example
0
1
2
3
4
5
6
7
8
9
10
4.0 5.0 6.0 7.0
% AC
%AirVoids
At Target p200 = Solid Lines
At Field Observed p200 = Dashed Lines
Reduction in AC
at 4.0% AV =
0.8% due to
+1.5% p200
Reduction in AV
at Opt AC = 1.8%
due to +1.5%
p200

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
What About Production?
 Lab Mix Design to Field Production
Differences are Real – Must Address
 What Occurs During Production that Affects
Gradation and Volumetrics?
Breakdown in the Drum (p200 ↑)
If p200 ↑ Post Plant what will be Done to Maintain
4.0% Air Voids, …?
Reduce %AC?
Reduced Durability
Is this Good or Bad?
%AC
Rutting
Durability

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 Desired
Volumetrics
Appropriate TV Δ’s
 P200 dosing in MD?
 Test Strip
 %AC, Gradation, Volumetrics – Same Sample
 …

26. Aggregate Breakdown Example
0
10
20
30
40
50
60
70
80
90
100
PercentPassing
Sieve Size ^ 0.45 Power (mm)
Hot Bin Blend
Ignition Oven Gradation
Spec Limit
Target Values
0.075
0.15
0.30 0.60 1.18 2.36 4.75 9.50 12.5 19.0
Over 5% on coarse sieves
and 2% on p200

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 Process
if PSP and OBC Δ ≤ 0.4% OK
If PSP and OBC Δ ≥ 0.4% Shut Down
QC/QA
if PSP and OBC Δ ≥ 0.0% PWL Compomised
Typical σT = 0.20

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. %AC Pay Factors for
Spec Tolerances = ±0.4%
0.75
0.80
0.85
0.90
0.95
1.00
1.05
0.00 0.10 0.20 0.30 0.40 0.50
StandardDeviation
PayFactor
Offset = 0
Offset = 0.1
Offset = 0.2
Typical Variability
1.01
0.95

30. %AC Pay Factors for
Spec Tolerances = ±0.3%
0.750.800.850.900.951.001.05
0.00 0.10 0.20 0.30 0.40 0.50
StandardDeviation
PayFactor
Offset = 0
Offset = 0.1
Offset = 0.2
Typical Variability
0.94
0.83

31. Superpave Experiences 2005
Stockpile Management
Pre-Superpave

32. Superpave Experiences -32
Stockpile Management
Post-Superpave

33. Additional Feeder Bins
 RAP Fractionation
 12 Bins at 1 Hot Plant?

34. Accurately Metering
Baghouse Fines?

35. Wasting Baghouse Fines?

36. Superpave is Technology Friendly
 Can Technically Address in Lab
Neat, PMB
RAP
RAS
WMA
…
 We Can Field Produce

37. Field Observations
 NMAS
¾” has ¾” Rock in It
t/NMAS ≥ 3, Max by Density Measurement
 BRZ can = Segregation (everywhere) & Workability
Challenges – 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. Field Observations
 Have Compacted up to 5.5” Lift with ¾” NMAS
 We Can Place and Compact Superpave Mixes
Tenderzone - special Kneeding compactors?

39. Training is Critical to Success!

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 Firms
Consider FHWA Efforts in Early 1990’s

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 and
City/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 Mix
Sensitivity
 Some Aggregate Sources will Be Challenging
 Required Plant Investments will Be Underestimated
 There will Need to Be Specification Iterations

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 Structural
Design, 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 for
Our IndustryOur Industry

43. QuestionsQuestions