1. Senior/Graduate
HMA Course
Quality control/quality assurance
Acceptance
Construction QC/QA Acceptance 1

2. What you will learn….
• The acceptance and compliance procedures
used for hot mix asphalt
Construction QC/QA Acceptance 2

3. ACCEPTANCE AND
COMPLIANCE
Did We Get What We Ordered?
Construction QC/QA Acceptance 3

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 specification
Construction QC/QA Acceptance 4

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. 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. 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 size
Construction QC/QA Acceptance 7

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. Percent Within Limits
Construction QC/QA Acceptance 9

10. PWL Concept
PWL = (PU + PL) - 100
In Terms of Area of the Distribution
PL
LSL
PWL
% AC
USL
Construction PU
QC/QA Acceptance 10

11. Spec
Percent Within Limits
Data
Target Value 5.0
Lot X s PWL
Limits ± 0.4
target 1 5.0 0.20 96
Lot 1 2 5.0 0.40 68
Lot 2
Upper limit
Lower limit
4.2 4.6 5.0 5.4 5.8
Asphalt Binder Content
Construction QC/QA Acceptance 11

12. Percent Within Limits
Target Value 5.0 Lot X s PWL
Limits ± 0.4 1 5.0 0.20 96
target
2 4.8 0.20 84
Lot 2
Lot 1
Upper limits
Lower limit
4.2 4.6 5.0 5.4 5.8
Asphalt Binder Content
Construction QC/QA Acceptance 12

13. PWL Approach
To get 100 % pay you
need to pay attention to
both accuracy and
precision
Construction QC/QA Acceptance 13

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 PWL
Construction QC/QA Acceptance 14

15. Percent Within Limits Using
Standard Deviation
Construction QC/QA Acceptance 15

16. EXERCISE
Calculation of
PWL and PD

17. Equations
-
USL - x
Q(u) = s
-
x - LSL
Q(L) = s
Construction QC/QA Acceptance 17

18. Acceptance Plan:
Percent Within Limits (PWL) Approach
1. Determine Random Sample Location Within Lot
2. Make Measurements at Locations or on
Material Samples
3. Determine Average of Samples:
n xi
x =Σ n
i=1
4. Determine Standard Deviation of Samples:
(xi - x)2
Σ
n
s=
i=1
n-1

19. Acceptance Plan:
Percent Within Limits (PWL) Approach
5. 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. 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 slide
Construction QC/QA Acceptance 20

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. Compute values
• The average is:
– 4.72 %
• Standard deviation for data is:
– 0.43
Construction QC/QA Acceptance 22

23. Compute QU
-
USL - x
Q(u) = s
5.94 - 4.72
Q(u) = 0.43
Q(u) = 2.83
P(u) = > 1.00
Construction QC/QA Acceptance 23

24. Compute QL
-
x - LSL
Q(L) = s
4.72 - 4.06
Q(L) =
0.43
Q(L) = 1.53
P(L) = 0.97
Construction QC/QA Acceptance 24

25. Percent Within Limits
Using
Conformal Index
Construction QC/QA Acceptance 25

26. Equations
-
USL - x
Q(u) =
CI
-
x - LSL
Q(L) =
CI
Construction QC/QA Acceptance 26

27. Acceptance Plan:
Percent Within Limits (PWL) Approach
1. Determine Random Sample Location Within Lot
2. Make Measurements at Locations or on
Material Samples
3. Determine Average of Samples:
n xi
x =Σ n
i=1
4. Determine Standard Deviation of Samples:
(xi – spec requirement)2
Σ
n
Sci =
i=1 n-1

28. Acceptance Plan:
Percent Within Limits (PWL) Approach
5. Determine Upper Quality Index, Qu:
(U - x)
QU =
S ci
(x - L)
QL =
6. Determine S Lower Quality Index, QL:
ci
7. Estimate PU and PL From Table Using
Calculated QU and QL

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 slide
Construction QC/QA Acceptance 29

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. Compute values
• The average is:
– 4.72 %
• Conformal Index for data is:
– 0.533
Construction QC/QA Acceptance 31

32. Compute QU
-
USL - x
Q(u) = Sci
5.94 - 4.72
Q(u) = 0.53
Q(u) = 2.30
P(u) = > 1.00
Construction QC/QA Acceptance 32

33. Compute QL
-
x - LSL
Q(L) = s
4.72 - 4.06
Q(L) =
0.53
Q(L) = 1.24
P(L) = 0.90
Construction QC/QA Acceptance 33

34. Questions?
Construction QC/QA Acceptance 34