Senior/Graduate                                   HMA Course  Quality Control / Quality Assurance           Sampling for Q...
Requirements For a Sampling and Testing               Program          1. Frequency of Tests?          2. Location of Samp...
Reasons for Sampling Materials   1 . Certification or Source Approval   2 . Process/Quality Control   3 . Acceptance   4 ....
Types of Sampling        1 . Judgment Sampling        2 . Quota Sampling        3 . Systematic Sampling        4 . STRATIF...
Lot or PopulationConstruction     QC QA Sampling    5
Sample from a LotSpecimen 1                         Specimen 3 Specimen 2 Construction     QC QA Sampling    6           7-4
Sampling Location              Random Locations          x    Biased LocationsConstruction   QC QA Sampling     7
Random SamplingRandom                 Versus                            Stratified                            RandomConstr...
Random Sampling• Any portion of the population has equal  chance of being selected• Bias is introduced when judgment is us...
RANDOM SAMPLING                     With simple random                    Sampling, All samples                     could ...
Stratified Random Sampling  Sublot         Sublot         Sublot         Sublot    1              2              3        ...
Sampling Roadway Location Example               LOT Size: 4000 LF       Pavement Width: 12 FT       4 Sample Cores per LOT...
LOT  Sublot          Sublot         Sublot         Sublot    1               2              3              4Sta         St...
Sublot 1- Sample Location  Longitudinal (X)               Transverse (Y)Construction    QC QA Sampling   14
RANDOM                                                    NUMBER               Sublot 2        Sublot 4              TABLE...
Sublot 1  Coordinate X = .74 x 1000 = 740 FT  Coordinate Y = .29 x 12 = 3.5 FT.       740 Feet                            ...
Sublot 2Coordinate X = 0.60 x 1000 = 600 FTCoordinate Y = 0.21 x 12 = 2.5 FT Construction     QC QA Sampling      17
Stratified Random Sampling  Sublot         Sublot         Sublot         Sublot    1              2              3        ...
Stratified Random Sampling              Sample Location       107+40      116+00   120+10            132+70Sublot         ...
Sampling at the HMA Plant         Example Problem• Lot size is 5000 tons• The sub-lot size is 1000 tons• Sublot samples – ...
Select Sublots• From a random number generator you got the  following:                 0.37                 0.90          ...
Select Sublots• The next step is to determine which ton you are going  to test within the 5000 MG (ton) lot.• The first sa...
Questions?Construction   QC QA Sampling   23
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Block 23 Sampling - Theory 13

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Block 23 Sampling - Theory 13

  1. 1. Senior/Graduate HMA Course Quality Control / Quality Assurance Sampling for Quality ControlConstruction QC QA Sampling 1
  2. 2. Requirements For a Sampling and Testing Program 1. Frequency of Tests? 2. Location of Samples? 3. Size of Samples? 7-2 Construction QC QA Sampling 2
  3. 3. Reasons for Sampling Materials 1 . Certification or Source Approval 2 . Process/Quality Control 3 . Acceptance 4 . Independent Verification Samples Construction QC QA Sampling 3
  4. 4. Types of Sampling 1 . Judgment Sampling 2 . Quota Sampling 3 . Systematic Sampling 4 . STRATIFIED SAMPLING 5 . RANDOM SAMPLINGConstruction QC QA Sampling 4
  5. 5. Lot or PopulationConstruction QC QA Sampling 5
  6. 6. Sample from a LotSpecimen 1 Specimen 3 Specimen 2 Construction QC QA Sampling 6 7-4
  7. 7. Sampling Location  Random Locations x Biased LocationsConstruction QC QA Sampling 7
  8. 8. Random SamplingRandom Versus Stratified RandomConstruction QC QA Sampling 8
  9. 9. Random Sampling• Any portion of the population has equal chance of being selected• Bias is introduced when judgment is used - Use the tables!• Use random number tablesConstruction QC QA Sampling 9
  10. 10. RANDOM SAMPLING With simple random Sampling, All samples could end Up in one section of a Roadway lot ROADWAY LOTConstruction QC QA Sampling 10
  11. 11. Stratified Random Sampling Sublot Sublot Sublot Sublot 1 2 3 4Sta Sta Sta Sta Sta100 110 120 130 140Construction QC QA Sampling 11
  12. 12. Sampling Roadway Location Example LOT Size: 4000 LF Pavement Width: 12 FT 4 Sample Cores per LOT LOT begins at Sta 100+00Construction QC QA Sampling 12
  13. 13. LOT Sublot Sublot Sublot Sublot 1 2 3 4Sta Sta Sta Sta Sta100 110 120 130 140 Construction QC QA Sampling 13
  14. 14. Sublot 1- Sample Location Longitudinal (X) Transverse (Y)Construction QC QA Sampling 14
  15. 15. RANDOM NUMBER Sublot 2 Sublot 4 TABLE Sublot 1 Sublot 3 74 60 01 27 43 X 29 21 78 01 43 Y 28 37 00 49 97 73 08 87 32 97 72 14 09 70 41Construction QC QA Sampling 15
  16. 16. Sublot 1 Coordinate X = .74 x 1000 = 740 FT Coordinate Y = .29 x 12 = 3.5 FT. 740 Feet 12 FT 3.5 Feet 1000 FeetConstruction QC QA Sampling 16
  17. 17. Sublot 2Coordinate X = 0.60 x 1000 = 600 FTCoordinate Y = 0.21 x 12 = 2.5 FT Construction QC QA Sampling 17
  18. 18. Stratified Random Sampling Sublot Sublot Sublot Sublot 1 2 3 4Sta Sta Sta Sta Sta100 110 120 130 140Construction QC QA Sampling 18
  19. 19. Stratified Random Sampling Sample Location 107+40 116+00 120+10 132+70Sublot Sublot Sublot 2 9.4’ 1 4 Sublot3.5’ 2.5’ 3 0.1’Construction QC QA Sampling 19
  20. 20. Sampling at the HMA Plant Example Problem• Lot size is 5000 tons• The sub-lot size is 1000 tons• Sublot samples – – Select a block of numbers from the random number table• Calculate the sampling sequenceConstruction QC QA Sampling 20
  21. 21. Select Sublots• From a random number generator you got the following: 0.37 0.90 0.66 0.67 0.68Construction QC QA Sampling 21
  22. 22. Select Sublots• The next step is to determine which ton you are going to test within the 5000 MG (ton) lot.• The first sample would be at 0.37 * 1000 or 370 MG (tons)• The second sample would be at 0.90 *1000 + 1000 or 1900 MG (tons)• The third sample would be at 0.66 * 1000 + 2000 or 2660 MG (tons)Construction QC QA Sampling 22
  23. 23. Questions?Construction QC QA Sampling 23

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