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Block 26 Acceptance 13

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Block 26 Acceptance 13

  1. 1. Senior/Graduate HMA Course Quality control/quality assurance AcceptanceConstruction QC/QA Acceptance 1
  2. 2. What you will learn….• The acceptance and compliance procedures used for hot mix asphaltConstruction QC/QA Acceptance 2
  3. 3. ACCEPTANCE AND COMPLIANCE Did We Get What We Ordered?Construction QC/QA Acceptance 3
  4. 4. How do we set the spec limits• They are set using typical industry standard deviations• Then allowing three standard deviations from the target• When setting the limits – the number of tests to be included in the lot are considered• The more tests – the tighter the specificationConstruction QC/QA Acceptance 4
  5. 5. Typical Industry Standard Deviations• Based on extraction• Asphalt binder content: + 0.25 %• % Passing 4.75 mm (No. 4) and larger sieves: + 3 %• % Passing 2.36 (No 8) to .150 mm (No 100) sieves: + 2 %• Passing the 0.075 mm (No 200) sieve: + 0.7 %Construction QC/QA Acceptance 5
  6. 6. Typical Industry Standard Deviations (cont.)• Compacted mix• Air voids:+ 1.0 %• Voids in Mineral Aggregate (VMA): + 1.5 %• Voids filled with asphalt (VFA): + 5 % Construction QC/QA Acceptance 6
  7. 7. Equation• The following equation is used to set limits.• S(n) = s / n ½• Where – S(n) = standard deviation based on sample size n – S = standard deviation for material – n = sample sizeConstruction QC/QA Acceptance 7
  8. 8. Example• Thus for asphalt binder content where 4 samples will make up the lot size the spec limits would be:• S = 0.25 and n = 4• S(n) = 0.25 / square root (4)• S(n) = 0.125• For three standard deviations the spec limits would be plus/minus 0.375 %.Construction QC/QA Acceptance 8
  9. 9. Percent Within LimitsConstruction QC/QA Acceptance 9
  10. 10. PWL Concept PWL = (PU + PL) - 100 In Terms of Area of the Distribution PL LSL PWL % AC USLConstruction PU QC/QA Acceptance 10
  11. 11. Spec Percent Within Limits DataTarget Value 5.0 Lot X s PWLLimits ± 0.4 target 1 5.0 0.20 96 Lot 1 2 5.0 0.40 68 Lot 2 Upper limitLower limit4.2 4.6 5.0 5.4 5.8 Asphalt Binder ContentConstruction QC/QA Acceptance 11
  12. 12. Percent Within LimitsTarget Value 5.0 Lot X s PWLLimits ± 0.4 1 5.0 0.20 96 target 2 4.8 0.20 84 Lot 2 Lot 1 Upper limitsLower limit4.2 4.6 5.0 5.4 5.8 Asphalt Binder ContentConstruction QC/QA Acceptance 12
  13. 13. PWL ApproachTo get 100 % pay youneed to pay attention to both accuracy and precisionConstruction QC/QA Acceptance 13
  14. 14. Steps• Sample the material using an appropriate random number system• Determine the average for the lot• Determine the standard deviation “s” for each lot• For Air voids, VMA and binder content calculate the upper and lower quality indices and the associated PWL• For in-place density, calculate the lower quality index and associated PWLConstruction QC/QA Acceptance 14
  15. 15. Percent Within Limits Using Standard DeviationConstruction QC/QA Acceptance 15
  16. 16. EXERCISECalculation ofPWL and PD
  17. 17. Equations - USL - x Q(u) = s - x - LSL Q(L) = sConstruction QC/QA Acceptance 17
  18. 18. Acceptance Plan:Percent Within Limits (PWL) Approach1. Determine Random Sample Location Within Lot2. Make Measurements at Locations or on Material Samples3. Determine Average of Samples: n xi x =Σ n i=14. Determine Standard Deviation of Samples: (xi - x)2 Σ n s= i=1 n-1
  19. 19. Acceptance Plan: Percent Within Limits (PWL) Approach5. Determine Upper Quality Index, Qu: (U - x) QU = s (x - L) QL =6. Determine sLower Quality Index, QL:7. Estimate PU and PL From Table Using Calculated QU and QL
  20. 20. Example Problem• Percent passing 0.075 sieve – Test 1 : 4.1 – Test 2: 4.5 – Test 3: 4.8 – Test 4: 5.0 – Test 5: 5.1• Specification Target: 5.0 %• Allowable tolerance: See next slideConstruction QC/QA Acceptance 20
  21. 21. Set Spec Limits• The typical standard deviation from industry is 0.7 %; therefore: – S = 0.7 and n = 5 – S(n) = 0.7 / square root (5) – S(n) = 0.7/2.236 = 0.313• For three standard deviations the spec limits would be + 0.94 %.• Therefore: – Upper spec limit = 5.94 % – Lower spec limit = 4.06 %Construction QC/QA Acceptance 21
  22. 22. Compute values• The average is: – 4.72 %• Standard deviation for data is: – 0.43Construction QC/QA Acceptance 22
  23. 23. Compute QU - USL - x Q(u) = s 5.94 - 4.72 Q(u) = 0.43 Q(u) = 2.83 P(u) = > 1.00Construction QC/QA Acceptance 23
  24. 24. Compute QL - x - LSL Q(L) = s 4.72 - 4.06 Q(L) = 0.43 Q(L) = 1.53 P(L) = 0.97Construction QC/QA Acceptance 24
  25. 25. Percent Within Limits Using Conformal IndexConstruction QC/QA Acceptance 25
  26. 26. Equations - USL - x Q(u) = CI - x - LSL Q(L) = CIConstruction QC/QA Acceptance 26
  27. 27. Acceptance Plan:Percent Within Limits (PWL) Approach1. Determine Random Sample Location Within Lot2. Make Measurements at Locations or on Material Samples3. Determine Average of Samples: n xi x =Σ n i=14. Determine Standard Deviation of Samples: (xi – spec requirement)2 Σ n Sci = i=1 n-1
  28. 28. Acceptance Plan: Percent Within Limits (PWL) Approach5. Determine Upper Quality Index, Qu: (U - x) QU = S ci (x - L) QL =6. Determine S Lower Quality Index, QL: ci7. Estimate PU and PL From Table Using Calculated QU and QL
  29. 29. Example Problem• Percent passing 0.075 sieve – Test 1 : 4.1 – Test 2: 4.5 – Test 3: 4.8 – Test 4: 5.0 – Test 5: 5.1• Specification Target: 5.0 %• Allowable tolerance: See next slideConstruction QC/QA Acceptance 29
  30. 30. Set Spec Limits• The typical standard deviation from industry is 0.7 %; therefore: – S = 0.7 and n = 5 – S(n) = 0.7 / square root (5) – S(n) = 0.7/2.236 = 0.313• For three standard deviations the spec limits would be + 0.94 %.• Therefore: – Upper spec limit = 5.94 % – Lower spec limit = 4.06 %Construction QC/QA Acceptance 30
  31. 31. Compute values• The average is: – 4.72 %• Conformal Index for data is: – 0.533Construction QC/QA Acceptance 31
  32. 32. Compute QU - USL - x Q(u) = Sci 5.94 - 4.72 Q(u) = 0.53 Q(u) = 2.30 P(u) = > 1.00Construction QC/QA Acceptance 32
  33. 33. Compute QL - x - LSL Q(L) = s 4.72 - 4.06 Q(L) = 0.53 Q(L) = 1.24 P(L) = 0.90Construction QC/QA Acceptance 33
  34. 34. Questions?Construction QC/QA Acceptance 34

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