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- 1. Senior/Graduate HMA Course Quality Control / Quality Assurance Sampling for Quality ControlConstruction QC QA Sampling 1
- 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. 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. Types of Sampling 1 . Judgment Sampling 2 . Quota Sampling 3 . Systematic Sampling 4 . STRATIFIED SAMPLING 5 . RANDOM SAMPLINGConstruction QC QA Sampling 4
- 5. Lot or PopulationConstruction QC QA Sampling 5
- 6. Sample from a LotSpecimen 1 Specimen 3 Specimen 2 Construction QC QA Sampling 6 7-4
- 7. Sampling Location Random Locations x Biased LocationsConstruction QC QA Sampling 7
- 8. Random SamplingRandom Versus Stratified RandomConstruction QC QA Sampling 8
- 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. 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. Stratified Random Sampling Sublot Sublot Sublot Sublot 1 2 3 4Sta Sta Sta Sta Sta100 110 120 130 140Construction QC QA Sampling 11
- 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. LOT Sublot Sublot Sublot Sublot 1 2 3 4Sta Sta Sta Sta Sta100 110 120 130 140 Construction QC QA Sampling 13
- 14. Sublot 1- Sample Location Longitudinal (X) Transverse (Y)Construction QC QA Sampling 14
- 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. 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. Sublot 2Coordinate X = 0.60 x 1000 = 600 FTCoordinate Y = 0.21 x 12 = 2.5 FT Construction QC QA Sampling 17
- 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. 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. 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. 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. 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. Questions?Construction QC QA Sampling 23

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