block 26 acceptance 13
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Construction QC/QA Acceptance 1
Quality control/quality assurance
Acceptance
Senior/GraduateHMA Course
Construction QC/QA Acceptance 2
What you will learn….
• The acceptance and compliance procedures used for hot mix asphalt
Construction QC/QA Acceptance 3
ACCEPTANCE AND COMPLIANCE
Did We Get What We Ordered?
Construction QC/QA Acceptance 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 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 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 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 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 9
Percent Within Limits
Construction QC/QA Acceptance 10
PWL Concept
% AC
PWL
PU
PL
USL
LSL
PWL = (PU + PL) - 100
In Terms of Area of the Distribution
Construction QC/QA Acceptance 11
Percent Within Limits
Lot X s PWL
1 5.0 0.20 96
2 5.0 0.40 68
Target Value 5.0
Limits ± 0.4
Lot 1
Lot 2
Asphalt Binder Content4.2 4.6 5.0 5.4 5.8
Upper limit
Lower limit
target
Spec Data
Construction QC/QA Acceptance 12
Percent Within Limits
Lot X s PWL
1 5.0 0.20 96
2 4.8 0.20 84
Lot 1Lot 2
Asphalt Binder Content4.2 4.6 5.0 5.4 5.8
Target Value 5.0
Limits ± 0.4 target
Upper limitsLower limit
Construction QC/QA Acceptance 13
PWL Approach
To get 100 % pay you need to pay attention to
both accuracy and precision
Construction QC/QA Acceptance 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 15
Percent Within Limits Using Standard Deviation
EXERCISE
Calculation of
PWL and PD
Construction QC/QA Acceptance 17
Equations
Q(u) =
Q(L) =
USL - x
x - LSL s
s
-
-
1. Determine Random Sample Location Within Lot
2. Make Measurements at Locations or on Material Samples
3. Determine Average of Samples:
4. Determine Standard Deviation of Samples:
Acceptance Plan:Percent Within Limits (PWL) Approach
x = xi
nn
i=1
s = (xi - x)2
n-1ni=1
Acceptance Plan:Percent Within Limits (PWL) Approach
5. Determine Upper Quality Index, Qu:
6. Determine Lower Quality Index, QL:
7. Estimate PU and PL From Table Using Calculated QU and QL
8. Total Percent Within Limits = (PU + PL) - 100
QL = (x - L)
s
QU = (U - x)
s
Construction QC/QA Acceptance 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 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 %
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Compute values
• The average is: – 4.72 %
• Standard deviation for data is:– 0.43
Construction QC/QA Acceptance 23
Compute QU
Q(u) = USL - x s
-
Q(u) =
Q(u) = 2.83
5.94 - 4.72 0.43
P(u) = > 1.00
Construction QC/QA Acceptance 24
Compute QL
Q(L) =
Q(L) =
x - LSL
4.72 - 4.06 0.43
s
-
Q(L) = 1.53
P(L) = 0.97
Construction QC/QA Acceptance 25
Percent Within Limits Using
Conformal Index
Construction QC/QA Acceptance 26
Equations
Q(u) =
Q(L) =
USL - x
x - LSL
CI
CI
-
-
1. Determine Random Sample Location Within Lot
2. Make Measurements at Locations or on Material Samples
3. Determine Average of Samples:
4. Determine Standard Deviation of Samples:
Acceptance Plan:Percent Within Limits (PWL) Approach
x = xi
nn
i=1
Sci = (xi – spec requirement)2
n-1ni=1
Acceptance Plan:Percent Within Limits (PWL) Approach
5. Determine Upper Quality Index, Qu:
6. Determine Lower Quality Index, QL:
7. Estimate PU and PL From Table Using Calculated QU and QL
8. Total Percent Within Limits = (PU + PL) - 100
QL = (x - L)
S ci
QU = (U - x)
S ci
Construction QC/QA Acceptance 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 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 31
Compute values
• The average is: – 4.72 %
• Conformal Index for data is:– 0.533
Construction QC/QA Acceptance 32
Compute QU
Q(u) = USL - x Sci
-
Q(u) =
Q(u) = 2.30
5.94 - 4.72 0.53
P(u) = > 1.00
Construction QC/QA Acceptance 33
Compute QL
Q(L) =
Q(L) =
x - LSL
4.72 - 4.06 0.53
s
-
Q(L) = 1.24
P(L) = 0.90
Construction QC/QA Acceptance 34
Questions?
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