Tony Limas, California Group Quality Manager, Granite Construction, delivers a presentation, "The Return of Statistical Pay Factors" for state highway construction. Presentation delivered at the CalAPA Spring Asphalt Pavement Conference, held March 20-21, 2019 in Ontario, CA.

1. THE RETURN OF STATISTICALTHE RETURN OF STATISTICAL
PAY FACTORSPAY FACTORS
CalAPA Fall Conference
March 20 - 21, 2019
Ontario, CA
Tony Limas
Granite Construction Inc.

2. Today’s DiscussionToday’s Discussion
• BackgroundBackground
• Testing and CertificationTesting and Certification
• Mix Design RequirementsMix Design Requirements
• QC & Acceptance Testing (NPF)QC & Acceptance Testing (NPF)
• Quality Control PlanQuality Control Plan
• Statistical Pay Factor RequirementsStatistical Pay Factor Requirements
• Verification TestingVerification Testing
• Dispute ResolutionDispute Resolution
• AcceptanceAcceptance
• QuestionsQuestions
22

3. BACKGROUNDBACKGROUND

4. BackgroundBackground
• CT QC/QA Specifications ceased forCT QC/QA Specifications ceased for
Superpave Pilot ProjectsSuperpave Pilot Projects
• Superpave Pilot Projects CompletedSuperpave Pilot Projects Completed
• Ready for Statistical Pay Factor (SPF) PilotReady for Statistical Pay Factor (SPF) Pilot
Projects (1 construction season)Projects (1 construction season)
44

5. CT Specifications (Old vs New)CT Specifications (Old vs New)
• Old QC/QA SpecsOld QC/QA Specs
• MethodMethod
• Standard ProcessStandard Process
• QC/QA ProcessQC/QA Process
Both Standard and QC could include Method CompactionBoth Standard and QC could include Method Compaction
• New SpecsNew Specs
• SuperPave Specs w/o Statistical Pay Factors (Standard)SuperPave Specs w/o Statistical Pay Factors (Standard)
• SuperPave Specs w Statistical Pay FactorsSuperPave Specs w Statistical Pay Factors
Both could include Method CompactionBoth could include Method Compaction
55

6. Elements of the “Ideal” SPFElements of the “Ideal” SPF
SpecificationSpecification
• Reproducible Test MethodsReproducible Test Methods
• Well Understood Variability (standardWell Understood Variability (standard
deviation)deviation)
• Existence of Strong Relationships betweenExistence of Strong Relationships between
Tests (Measured Properties) and PavementTests (Measured Properties) and Pavement
PerformancePerformance

7. 7
PWL and Seller’s Risk
S
(n=1)
PWL
Risk
(α)
0.20 5.0 95 5%
7 SH$ %LQGHURQWHQW
4.6 5.0 5.4
8SSHU/ LP LW/ RZHU/ LP LW
Mean
5.0%
2.5%2.5%
47.5%
Target Value + 0.40
NTS
Target Value/Mean

8. TESTING AND CERTICATI0NTESTING AND CERTICATI0N

9. Quality Control TestingQuality Control Testing
• QC - Testing performed by Contractor toQC - Testing performed by Contractor to
control product properties and determinecontrol product properties and determine
the quality of the product being producedthe quality of the product being produced
• Non Pay Factor MaterialNon Pay Factor Material
• Pay Factor MaterialPay Factor Material

10. Acceptance TestingAcceptance Testing
• Testing performed by Engineer toTesting performed by Engineer to
determine properties of the materialdetermine properties of the material
being producedbeing produced
• Optional TestingOptional Testing
• Non Pay Factor Quality CharacteristicsNon Pay Factor Quality Characteristics

11. Verification TestingVerification Testing
• Testing performed to verify theTesting performed to verify the
contractors QC test results for paymentcontractors QC test results for payment
• Performed by OwnerPerformed by Owner

12. Dispute Resolution TestingDispute Resolution Testing
• Testing performed by Independent 3Testing performed by Independent 3rdrd
party to resolve difference betweenparty to resolve difference between
contractor QC and owner Verificationcontractor QC and owner Verification
test resultstest results

13. Materials Tester CertificationMaterials Tester Certification
RequirementsRequirements
Must be Certified to Perform Test for QualityMust be Certified to Perform Test for Quality
Characteristics with Pay FactorsCharacteristics with Pay Factors
• IA CertificationIA Certification
• JTC CertificationJTC Certification

14. MIX DESIGN REQUIRMENTSMIX DESIGN REQUIRMENTS

15. Mix Design Requirements Type AMix Design Requirements Type A
• No change from 2018 StandardNo change from 2018 Standard
SpecificationsSpecifications
• Air voidsAir voids
• GyrationsGyrations
• Voids in Mineral AggregateVoids in Mineral Aggregate
• Dust ProportionDust Proportion
• Hamburg Wheel TrackHamburg Wheel Track
• Moisture SusceptibilityMoisture Susceptibility
1515

16. Mix Design Requirements RHMAMix Design Requirements RHMA
• No Change from 2018 Standard SpecificationsNo Change from 2018 Standard Specifications
• Air voidsAir voids
• GyrationsGyrations
• Voids in Mineral AggregateVoids in Mineral Aggregate
• Dust ProportionDust Proportion
• Hamburg Wheel TrackHamburg Wheel Track
• Moisture SusceptibilityMoisture Susceptibility
1616

17. Hamburg/TSR Testing RequirementsHamburg/TSR Testing Requirements
• Required for mix verification hot dropRequired for mix verification hot drop
• Required for PSUERequired for PSUE
• Material sampled at PlantMaterial sampled at Plant
• Not required during production beyondNot required during production beyond
PSUEPSUE
1717

18. QALITY CONTROL andQALITY CONTROL and
ACCEPTANCE TESTINGACCEPTANCE TESTING

19. Quality Control Non-Pay FactorsQuality Control Non-Pay Factors
• Gradations (except No. 8 and 200Gradations (except No. 8 and 200
sieves)sieves)
• Sand EquivalentSand Equivalent
• Moisture ContentMoisture Content
• Crushed ParticlesCrushed Particles
• Los Angeles RattlerLos Angeles Rattler
1919

20. Quality Control Non-Pay FactorsQuality Control Non-Pay Factors
• Flat and Elongated ParticlesFlat and Elongated Particles
• Fine Aggregate AngularityFine Aggregate Angularity
• HMA Moisture ContentHMA Moisture Content
• Voids in Mineral AggregateVoids in Mineral Aggregate
• Dust ProportionDust Proportion
2020

21. Quality Control Non-Pay FactorsQuality Control Non-Pay Factors
• Except for smoothness if 2 consecutive non-Except for smoothness if 2 consecutive non-
pay factor QC test results or any 3 QC testpay factor QC test results or any 3 QC test
results for 1 days production do not complyresults for 1 days production do not comply
with the materials specifications:with the materials specifications:
• Stop HMA ProductionStop HMA Production
• Notify the EngineerNotify the Engineer
• Take Corrective ActionTake Corrective Action
• Demonstrate Compliance Before ResumingDemonstrate Compliance Before Resuming
WorkWork
2121

22. Quality Control Non-PayQuality Control Non-Pay
FactorsFactors
• Multiple sieves out of complianceMultiple sieves out of compliance
considered 1 failed gradationconsidered 1 failed gradation
• Go – No Go DecisionGo – No Go Decision
• Material not subject rejectionMaterial not subject rejection
• Material not subject to penaltyMaterial not subject to penalty

23. Acceptance Testing Non-PayAcceptance Testing Non-Pay
FactorFactor
• Optional testing performed by EngineerOptional testing performed by Engineer
to verify compliance with Non-Payto verify compliance with Non-Pay
Factor Quality CharacteristicsFactor Quality Characteristics

24. Acceptance Testing Non-Pay FactorAcceptance Testing Non-Pay Factor
• Except for smoothness if 2 consecutive non-Except for smoothness if 2 consecutive non-
pay factor QC test results or any 3 QC testpay factor QC test results or any 3 QC test
results for 1 days production do not complyresults for 1 days production do not comply
with the materials specifications:with the materials specifications:
• Notify ContractorNotify Contractor
• Contractor stop HMA ProductionContractor stop HMA Production
• Contractor Take corrective ActionContractor Take corrective Action
• Contractor Demonstrate compliance beforeContractor Demonstrate compliance before
resuming Workresuming Work
2424

25. Acceptance Testing Non-PayAcceptance Testing Non-Pay
FactorFactor
• Multiple sieves out of compliance considered 1 failedMultiple sieves out of compliance considered 1 failed
gradationgradation
• Engineer will notify Contractor of failing AcceptanceEngineer will notify Contractor of failing Acceptance
TestsTests
• Go No-Go DecisionGo No-Go Decision
• Material not subject rejectionMaterial not subject rejection
• Material not subject to penaltyMaterial not subject to penalty

26. QUALITY CONTROL PLANQUALITY CONTROL PLAN

27. ContractoContractor Quality Control Planr Quality Control Plan
• Per Quality Control ManualPer Quality Control Manual
RequirementsRequirements
• Prepared by ContractorPrepared by Contractor
• Approved by EngineerApproved by Engineer
2727

28. Quality Control PlanQuality Control Plan
• Purpose of PlanPurpose of Plan
• Keep process in controlKeep process in control
• Quickly determine when the process has gone outQuickly determine when the process has gone out
of controlof control
• Planned response to correct deficiencies bringingPlanned response to correct deficiencies bringing
the process back into controlthe process back into control
•
2828

29. QC Staffing RequirementsQC Staffing Requirements
Field Compaction Requirement QC Staffing Level
Excluding QC Manager (see note
3)
Method Compaction 3 (See note 1)
Density Testing 4 (see Note 2
2929
(1) One HMA inspector at the plant, one at the site of placement, a third(1) One HMA inspector at the plant, one at the site of placement, a third
where the contractor deems necessarywhere the contractor deems necessary
(2) One HMA inspector at the plant, one at the site of placement(2) One HMA inspector at the plant, one at the site of placement
performing density testing, one additional at the site of placement, and aperforming density testing, one additional at the site of placement, and a
forth where the contractor deems necessaryforth where the contractor deems necessary
(3)The contractor must provide a qualified sampler to pull the Engineers(3)The contractor must provide a qualified sampler to pull the Engineers
verification samples of HMA and density cores. The contractor must splitverification samples of HMA and density cores. The contractor must split
the HMA samples into four parts, provide three parts to the Engineer andthe HMA samples into four parts, provide three parts to the Engineer and
keep one. This person may be one of the required staff. The contractorskeep one. This person may be one of the required staff. The contractors
portion may not be used for QC testing.portion may not be used for QC testing.

30. STATISTICAL PAY FACTORSTATISTICAL PAY FACTOR
REQUIRMENTSREQUIRMENTS

31. Statistical Pay FactorsStatistical Pay Factors
• 20 Sublots per Lot20 Sublots per Lot
• 750 tons/sublot750 tons/sublot
• 15,000 tons per Lot15,000 tons per Lot
• Maximum Bonus 5%Maximum Bonus 5%

32. New Lot Required When:New Lot Required When:
• 20 Sublots are completed20 Sublots are completed
• JMF ChangesJMF Changes
• Material source changesMaterial source changes
• Work Suspended (unsatisfactory Performance)Work Suspended (unsatisfactory Performance)
• Production stops for 30 daysProduction stops for 30 days
• Contractor delayContractor delay
• Seasonal work stoppageSeasonal work stoppage
• Phases of work (ramps etc.)Phases of work (ramps etc.)

33. Type A Quality Characteristic’sType A Quality Characteristic’s
With Pay FactorsWith Pay Factors
Quality Characteristic Test method Tolerance Weight
No. 8 Sieve AASHTO T 27/30 Per Gradation 0.05
No. 200 Sieve AASHTO T 27/30 Per Gradation 0.10
Asphalt Binder Content
AASHTO T 308
(Method A)
± 0.40 0.25
Air Voids Content at Ndesign AASHTO T 269 ± 1.5 0.20
Density of Core (% of max
theoretical density)
AASHTO T 275
(Method A)
AAHTO T 209
(Method A)
92.0 - 96.0 0.40
3333

34. RHMA Quality Characteristic’sRHMA Quality Characteristic’s
With Pay FactorsWith Pay Factors
Quality Characteristic Test Method Tolerance Weight
No. 8 Sieve AASHTO T 27/30 Per Gradation 0.05
No. 200 Sieve AASHTO T 27/30 Per Gradation 0.10
Asphalt Binder Content
AASHTO T 308
(Method A)
± 0.45 0.25
Air Voids Content at Ndesign AASHTO T 269 ± 1.8 0.20
Density of Core (% of max
theoretical density)
AASHTO T 275
(Method A)
AAHTO T 209
(Method A)
91.0 – 96.0 0.40
3434

35. QC Sampling and TestingQC Sampling and Testing
• Contractor Obtains Random SamplesContractor Obtains Random Samples
3535
Gradation 1/750 Tons
Binder Content 1/750 Tons
Air Voids 1 /1500 Tons
Relative density 1 core/250 tons (3 cores/750 tons)

36. QC Sampling and TestingQC Sampling and Testing
Contractor Sampling Locations
• Plant (drum, silo, drag slat)
• Truck (plant, field)
• Windrow (plant or field)
• Behind Paver
• May be different than Verification
sample location
3636

37. Production Star-Up EvaluationProduction Star-Up Evaluation
(PSUE)(PSUE)
• 750 ton minimum tonnage
• Perform PSUE “light” when PSUE is within
45 days of date on approved (signed) CEM
3513
• If production stops for 30 to 60 days
perform PSUE “light”
• If production stops for 60 days perform full
PSUE
• In all cases, if PSUE fails do not proceed to
production
3737

38. QC Sampling and TestingQC Sampling and Testing
• Sampling and Testing NotesSampling and Testing Notes
• GradationGradation
• Binder ContentBinder Content
• Air VoidsAir Voids
• Relative densityRelative density
3838

39. QC Sampling and Testing NotesQC Sampling and Testing Notes
• Gradations
• 1 Gradation test every 750 tons
• Results based on single Gradation test
• Test results reported to whole number
with exception to the No. 200 sieve
• Test results for No. 200 sieve reported
to 0.1
3939

40. QC Sampling and Testing NotesQC Sampling and Testing Notes
• Binder Content
• 1 Ignition Oven Binder test every 750
tons
• Results based on single test
• Test results reported to 0.01
4040

41. QC Sampling and Testing NotesQC Sampling and Testing Notes
• Air Voids
• 1 Air Void test every 1500 tons
• Based on average of 3 briquettes and
minimum 2 Gmm (RICE) replicates
• Briquettes and Gmm obtained from one
random sample taken every 1500 tons
• Test results reported to 0.10%
4141

42. QC Sampling and Testing NotesQC Sampling and Testing Notes
• Relative Density Gauge Testing
• Non Nuclear Gauge allowed
• Correlation to cores not required
4242

43. QC Sampling and Testing NotesQC Sampling and Testing Notes
• Relative Density Based on
Cores/Gmm
• 1 test every 750 tons
• 1 core/250 tons (3/750 tons)
• 4 inch cores
• Use Average of 3 cores and average of 3
Gmm’s to determine percent relative density
• Test results reported to 0.10
4343

44. QC Sampling and Testing NotesQC Sampling and Testing Notes
• Relative Density Gmm
Requirements
• Run minimum 3 Gmm on 1st
day of production
• Following 1st
day of production contractor will
run min. 1 Gmm/day and use running average
of 3 most recent Gmm to determine relative
density
4444

45. QC Test (Pay Factors)QC Test (Pay Factors)
• Contractor enters QC test
results in HMA SPF program to
determine Quality Factor(s)
• Determine individual and
composite Quality Factors
• Submits SPF results to
Engineer daily 4545

46. QC Test Quality FactorsQC Test Quality Factors
• If composite or individual Quality factor is
less than 0.90 or 0.75 for No. 8 sieve
contractor:
• Stops work
• Notifies the Engineer in writing
• Takes corrective action before resuming
production
• Documents all steps taken on CEM Form
4646

47. VERIFICATION TESTINGVERIFICATION TESTING

48. Engineer Verification TestingEngineer Verification Testing
• Engineer Obtains Random SamplesEngineer Obtains Random Samples
4848
Gradation Verification ratio 1:5 (3 sublots/lot min.)Verification ratio 1:5 (3 sublots/lot min.)
Binder Content Verification ratio 1:5 (3 sublots/lot min.)Verification ratio 1:5 (3 sublots/lot min.)
Air Voids Verification ratio 1:5 (3 sublots/lot min.)Verification ratio 1:5 (3 sublots/lot min.)
Relative Density Verification ratio 1:5 (3 sublots/lot min.)Verification ratio 1:5 (3 sublots/lot min.)

49. Engineer Verification TestingEngineer Verification Testing
• Engineer Sampling locations
• Plant (drum, silo, drag slat)
• Truck (plant or field)
• Windrow (plant or Field)
• Behind Paver
• May be different than QC sample
location
4949

50. Engineer Verification Testing NotesEngineer Verification Testing Notes
• GradationGradation
• Binder ContentBinder Content
• Air VoidsAir Voids
• Relative densityRelative density
5050

51. Engineer Verification Testing NotesEngineer Verification Testing Notes
• Gradations
• Results based on single Gradation test
• Test results reported to whole number
with exception to the No. 200 sieve
• Test results for No. 200 sieve reported
to 0.1
5151

52. Engineer Verification Testing NotesEngineer Verification Testing Notes
• Binder Content
• Results based on single testResults based on single test
• Test results reported to 0.01
5252

53. Engineer Verification Testing NotesEngineer Verification Testing Notes
• Air Voids
• Based on average of 3 replicate
briquettes and 2 Gmm replicates
• Gmm from random sample taken from
same sublot as briquette material
5353

54. Engineer Verification Testing NotesEngineer Verification Testing Notes
• Relative Density
• Based on pavement cores and Gmm
• 4 inch cores
• 1 core/250 tons (3/750 tons)
• Use Average of 3 cores and average of
min. 2 replicate Gmm’s to determine
percent Relative Density
• Run Gmm on material from sublot with
verification cores
5454

55. Verification CriteriaVerification Criteria
Used to Compare QC Data to
Verification Data to verify that
contractors QC test results are
acceptable as a basis of payment
•F-testF-test
•T-testT-test
•Allowable Test Difference (ATD)Allowable Test Difference (ATD)
5555

56. VerificationVerification
F-testF-test
• A statistical test that is used to determine
whether two populations having normal
distribution have the same variances or
standard deviation
• If F-test is passed use Rule 1 for to determine the
Degrees of Freedom for T-test
• If F-test fails use Rule 2 for to determine the
Degrees of Freedom for T-test
5656

57. VerificationVerification
T-testT-test
•The t-test is a type of inferential statistic used
to determine if there is significant difference
between the means of two groups of data
indicating that the test results are statically
not from the same population
5757

58. VerificationVerification
Allowable Test Differences (ATD)
When the contractors data is not verified by the
T-test and the QC and verification means are
within the following allowable differences the
material is considered to be verified
5858
Item ATD
Gradation ≤ 1.0 percent
Binder Content ≤ 0.1 percent
Air Voids ≤ 0.2 percent
Relative Density ≤ 0.5 percent

59. Verification TestingVerification Testing
• Engineer provides Verification Test
Results to Contractor within 5
Business Days of Completion of
Lot?
5959

60. Verification TestingVerification Testing
• If material is not verified isolate
material related to non-Verification
– Reject Material
– Terminate Lot
• Recalculate pay factor for
remaining sublots using QC Data
without QC test data representing
rejected material 6060

61. Verification TestingVerification Testing
• Prior to resuming production on
next Lot:
• Take corrective Action
• Demonstrate compliance
6161

62. DIPUTE RESOLUTIONDIPUTE RESOLUTION

63. Dispute ResolutionDispute Resolution
• Notify Engineer and Submit copies of
paperwork including work sheets used
to determine the disputed test results
within 3 business days of receiving the
Engineers test results
6363

64. 6. Dispute Resolution6. Dispute Resolution
• Mix Design Verification Hot Drop
• Production Start-up Evaluation
(PSUE)
• Production
• Verification Testing
• Acceptance Testing 6464

65. Dispute Resolution ProcessDispute Resolution Process
• Review of Sampling Procedures
• Review Test Report and Calculations
• Witness Tester and Laboratory
Operations
• Contractors Testing
• Engineers Testing
• Independent Third Party performs
Testing using Split Referee Samples
6565

66. Dispute Resolution TestingDispute Resolution Testing
• Use Split Samples from Verification
samples
• 4 Way Split Samples
• 1 sample Engineer Verification
• 1 Sample Contractor (Information
Only)
• 2 Samples Dispute Resolution
• Retained by Engineer
• Contractor assist with all sampling
6666

67. Dispute Resolution GradationDispute Resolution Gradation
• If No.8 or No. 200 sieves are
not verified both sieves are
evaluated for dispute testing
6767

68. Dispute CoresDispute Cores
• In addition to Verification cores:
• Take 3 additional cores for each 250
tons
• 2 cores for Engineer
• 1 core for Contractor (information
only)
• Core locations aligned longitudinally
1-2 feet apart
6868

69. ACCEPTANCEACCEPTANCE

70. Acceptance (Pay Factor Material)Acceptance (Pay Factor Material)
• Contractors Sampling, Inspection and Test ResultsContractors Sampling, Inspection and Test Results
CompleteComplete
• QC Test Results VerifiedQC Test Results Verified
• Engineer Visually Inspects PavementEngineer Visually Inspects Pavement
• Composite Pay Factor 0.90Composite Pay Factor 0.90
• Individual Pay Factors 90 or 0.75Individual Pay Factors 90 or 0.75 7070

71. QUESTIONS?QUESTIONS?