BITUMEN (ROUND 2)
PROFICIENCY TESTING PROGRAM
OCTOBER 2010
REPORT NO. 680
ACKNOWLEDGMENTS
PTA wishes to gratefully acknowledge the technical assistance provided for this
program by Mr B Chik of SAMI Bitumen Technologies Pty Ltd. This assistance included
preparation and homogeneity testing of the sample, along with input into the design of
the program, technical advice and discussion in the final report.
© COPYRIGHT 2010
PROFICIENCY TESTING AUSTRALIA
PO Box 7507, Silverwater, NSW 2128 Australia
CONTENTS
1.
Forward
2.
Features of the program
3.
Format of appendices
4.
Statistical design of the program
TABLE A: Summary Statistics
5.
Outlier Results
TABLE B: Outlier Results
6.
7.
PTA and Technical Adviser’s comments
1
1
2
2
3
4
4
5
TABLE C: Comparison of robust CVs from previous round
5
TABLE D: Comparison of outlier results from previous round
6
Measurement of Uncertainty (MU)
6
References
6
APPENDIX A – Summary of Results and Robust Z-Score Charts
Viscosity @ 135ºC
Density at 15.0 ºC
Penetration 25.0 ºC, 100g, 5s
Viscosity @ 60.0ºC
RTFOT Viscosity Change
RTFOT Value after treatment
Other tests
A1 – A2
A3 – A4
A5 – A6
A7 – A8
A9 – A10
A11 – A12
A13
APPENDIX B
Homogeneity Testing
B1
APPENDIX C
Instructions to Participants and Results Sheet
C1 – C2
1
1.
FOREWORD
This report summarises the results for Round 2 of a series of proficiency testing
programs on the analysis of Bitumen.
The exercise was conducted by Proficiency Testing Australia (PTA) in August 2010.
The aim of the program was to assess laboratories' ability to competently perform the
tests examined. The Program Coordinator was Ms L Galbraith.
2.
FEATURES OF THE PROGRAM
a)
A total of 13 laboratories were sent samples for the program. Two of the laboratories
requested an extra sample set to give 15 sets of results. All laboratories returned
results for inclusion in the final report.
b)
Participating laboratories were supplied two 800mL samples of Bitumen labelled PTA
Sample A and PTA Sample B.
c)
The following tests were performed on each sample:
PTA Sample A:
Viscosity @ 135.00C
Density at 15.00C (bottle)
Penetration 25.00C, 100g, 5s
PTA Sample B:
Vacuum Viscosity @ 60.00C (recommended to be tested before Rolling Thin Film Oven
Treatment (RTFOT))
RTFOT Viscosity Change (including the actual value after treatment)
d)
Ten randomly selected samples were analysed for homogeneity. Based on the results
of this testing, it was concluded that the samples were sufficiently homogeneous,
therefore any results later identified as outliers could not be attributed to any significant
sample variability (Appendix B).
e)
Laboratories were requested to perform the tests according to the "Instructions to
Participants" and to record their results on the accompanying "Results Sheet," both of
which were distributed to participants with the sample (Appendix C).
f)
Each laboratory was randomly allocated a unique code number for the program to
enable confidentiality of results. Reference to each laboratory in this report is made by
its unique code number. Participants reporting more than one set of results are
identified by their code number followed by a letter (A, B, C, etc), to distinguish the
different set of results submitted by the same laboratory.
2
3.
FORMAT OF APPENDICES
APPENDIX A
Appendix A lists all the results reported by the participating laboratories for each test.
Calculated robust z-scores, z-score charts and a table of robust statistics - number of
results, median, normalised interquartile range (IQR), robust coefficient of variation
(CV), minimum, maximum and range, are presented for the following tests:
•Viscosity @ 135ºC
•Density at 15.0 ºC
•Penetration 25.0 ºC, 100g, 5s
•Viscosity @ 60.0ºC
•RTFOT Viscosity Change (no z-score calculation)
•RTFOT Value after treatment
The remaining tests are included in the report to assist PTA and the Technical Adviser
to review results and are presented for information purposes only.
APPENDIX B
Contains details of homogeneity testing data.
APPENDIX C
Contains a copy of the “Instructions to Participants” and the “Results Sheet”
supplied to participants.
4.
STATISTICAL DESIGN OF THE PROGRAM
Robust statistical procedures were used to generate the z-scores and summary statistics
for the sample. Summary statistics include:







number of results;
median;
normalised IQR;
robust CV;
minimum;
maximum; and
range.
Robust z-scores were calculated for each laboratory based on the average of results
submitted for each analyte. Where only one result was submitted, that result was used to
calculate the z-score.
3
TABLE A: Summary Statistics
Test
No. of
Results
Median
Normalised
IQR
Viscosity @
135.0ºC
14
0.360
0.014
Density @ 15.0ºC
13
1042.00
2.22
Penetration @
25.0 ºC, 100g, 5s
14
71.5
4.1
Viscosity @ 60.0 ºC
12
186.20
3.06
RTFOT Viscosity
Change
10
170.5
3.9
RTFOT Value after
treatment
9
317.00
13.49
4
5.
OUTLIER RESULTS
In order to achieve the program's aim of assessing laboratories' testing performance, a
robust statistical approach, which uses z-scores, has been utilised. The z-score is a
measure of how far the result(s) is from the consensus value - a normalised value which
gives a "score" to each result relative to the other results in the group. Therefore a
z-score close to zero means that the result agrees well with those from other
laboratories. An outlier will be any result(s) which has an absolute z-score value greater
than or equal to three.
For each laboratory and for each sample, a single robust z-score was calculated. A
single robust z-score (denoted by Z) for a laboratory’s Sample A would then be:
Z=
A – median (A)
NormIQR (A)
For further information on the calculation and interpretation of z-scores, please see the
Guide to Proficiency Testing Australia (2008)¹.
TABLE B: Outlier Results
Sample A Test
Lab Code
Viscosity @ 135.0ºC
---
Density @ 15.0ºC
Lab 25
Penetration @ 25.0 ºC,
100g, 5s
Lab 11
Sample B Test
Lab Code
Viscosity @ 60.0 ºC
Lab 22
RTFOT Viscosity Change
Lab 10B
RTFOT Value after
treatment
Lab 10B
Note: --- indicates that no laboratories received outliers for this test
5
6. PTA AND TECHNICAL ADVISER’S COMMENTS
General Comments
Of the 13 participating laboratories, 4 laboratories have been identified as having
reported an outlier. Of the 72 total results, 5 outliers were reported; therefore 6.94% of
the total results have been identified as outlier results.
The following table gives a comparison of the robust CVs for tests common to the
previous program.
TABLE C: Comparison of robust CVs from previous round.
Test
Round 1
Round 2
Viscosity @
135.0ºC
4.5%
3.9%
Density @ 15.0ºC
0.05%
0.2%
Penetration @
25.0 ºC, 100g, 5s
3.7%
5.7%
Viscosity @ 60.0 ºC
3.3%
1.6 %
RTFOT Viscosity
Change
1.4%
2.3%
RTFOT Value after
treatment
~
4.3%
Note: ~ indicates that this test was not offered previously.
6
The following table shows a comparison of outlier results from Round 1 and Round 2
Bitumen proficiency testing programs.
TABLE D: Comparison of outlier results from previous round.
Test
Round 1
Round 2
Total Results
43
72
Number of outlier
results
4
5
% of total
9.30%
6.94%
Any laboratories reporting results with a z-score between 2 and 3 are encouraged to
review their procedures. Outlier laboratories not only need to review their method but
perhaps ensure results are to the correct basis or value.
The specified method for performing the tests was AS2341 (relevant sections). The
majority of participating laboratories followed this method. Other methods reported
included in-house methods.
The bitumen in this round has less variation because it is not readily oxidised, so
comparisons between present precision data and published precision data are invalid.
Measurement of Uncertainty (MU)
For this program participants were asked to report Measurement of Uncertainty (MU).
Laboratories who submitted results to be included in the final report responded with
varying values. Of the 15 participants, only 7 reported MU values.
Improvement is apparent in the overall performance of measurement of uncertainties.
Sufficient resources should be available so that participants can estimate MU
proficiently.
7.
REFERENCES
[1] “Guide to Proficiency Testing Australia” – 2008 (this document is located on
the PTA website at www.pta.asn.au under Programs / Documents).
[2] AS/NZS 2341.0:2002 – Methods of testing bitumen and related road making
products.
APPENDIX A
Summary of Results
and
Robust Z-Score Charts
A1
Viscosity @ 135.0ºC (Pa S)
Lab
Code
10A
10B
11
12A
12B
Result
MU
0.360
0.360
0.36
0.370*
0.3725*
15
0.33
±
16
17
18
20
21
0.396
0.344
0.34
0.35
0.3722*
±
±
±
±
25
0.366
±
36
39
0.402
0.36
±
±
#
#
#
#
#
Reproducibility
within 14.5%
0.12
0.03
#
0.06
26.1
Method
reproducibility
used instead of
site precision
data
0.016
0.01
No. of Results
Median
Normalised IQR
Robust CV
Minimum
Maximum
Range
Robust
Z-Score
0.00
0.00
0.00
0.70
0.88
Method / Technique
AS 2341.2
AS 2341.2
AS 2341.3
AS 2341.4
AS 2341.4
-2.11
AG: PT/T111
2.54
-1.13
-1.41
-0.70
0.86
AS 2341.4
AS 2341.4
AS 2341.2
In-house method
AS 2341.3
0.42
AS 2341.3
2.96
0.00
In-house method
AS2341.2
14
0.360
0.014
3.9%
0.33
0.402
0.072
Note: # indicates no response was returned
Note: * indicates submitted results converted to Pa S
15
17
18
Robust z-score
-1
20
0
39
11
1
-2
-3
Lab code
12B
21
12A
25
10B
10A
36
3
16
A2
Viscosity @ 135.0oC
2
A3
Density at 15.00C (bottle) Kg/m³
Lab
Code
10A
10B
11
12A
12B
16
17
18
20
21
Result
MU
1041*
1043*
1043.4
1042*
1042
1043.2
1037.3
1043.3
1039
1040.2
#
#
#
#
#
0.9 Kg/m3
3.4
#
#
0.7
Method
reproducibility
used instead
of site
precision
data
1
5.4
±
±
±
25
1.0424
±
36
39
1044
1040.8
±
±
No. of Results
Median
Normalised IQR
Robust CV
Minimum
Maximum
Range
Robust
Z-Score
-0.45
0.45
0.63
0.00
0.00
0.54
-2.11
0.58
-1.35
-0.81
-468.08
0.90
-0.54
Method / Technique
AS 2341.7
AS 2341.7
AS 2341.7
AS 2341.7
AS 2341.7
AS 2341.7
AS 2341.7
AS 2341.7
AS2341.7
AS2341.7
§
AS2341.7
In-house method
AS2341.7
13
1042.00
2.22
0.2%
1.0424
1044
1042.96
Note: # indicates no response was returned
§ denotes an outlier (i.e. |z-score| ≥ 3)
* indicates submitted results converted to Kg/m3
-3
25
17
20
Robust z-score
-1
10A
39
21
0
-2
Lab code
1
36
11
18
16
10B
12B
12A
A4
Density at 15.0oC
3
2
A5
Penetration 25.0ºC, 100g, 5s
Lab
Code
10A
10B
11
12A
12B
Result
MU
82
75
85
69
68
#
#
#
#
#
Reproducibility
within 8%
4pu or 8%
1
#
#
1
Method
reproducibility used
instead of site
precision data
2
0.05
15
67
±
16
17
18
20
21
69
69
76
73
70
±
±
25
73
±
36
39
71
72
±
±
±
No. of Results
Median
Normalised IQR
Robust CV
Minimum
Maximum
Range
Robust
Z-Score
2.58
0.86
3.31 §
-0.61
-0.86
Method / Technique
AS 2341.12
AS 2341.12
AS 2341.12
AS 2341.12
AS 2341.12
-1.10
AS 2341.12
-0.61
-0.61
1.10
0.37
-0.37
AS 2341.12
AS 2341.12
AS 2341.12
AS2341.12
AS2341.12
0.37
AS 2341.12
-0.12
0.12
AS2341.12
AS2341.12
14
71.5
4.1
5.7%
67
85
18
Note: # indicates no response was returned
Note: § denotes an outlier (i.e. |z-score| ≥ 3)
A6
3
-2
-3
Lab code
25
18
10B
36
21
17
16
12A
-1
12B
0
20
39
1
15
Robust z-score
2
11
10A
Penetration 25.0oC, 100g, 5s
A7
Viscosity @ 60.0ºC (Pa S)
Lab
Code
10A
10B
11
16
17
18
20
21
22
Result
MU
177.7
181.4
187
185
181.5
194
187
186.4
200
#
#
#
0.12
6.4
#
0.06
13
#
Method
reproducibility
used instead of
site precision data
5
0.01
±
±
±
±
±
25
186
36
39
185
192
No. of Results
Median
Normalised IQR
Robust CV
Minimum
Maximum
Range
±
±
Robust
Z-Score
-2.78
-1.57
0.26
-0.39
-1.54
2.55
0.26
0.07
4.51 §
Method / Technique
AS 2341.1
AS 2341.2
AS 2341.2
AS 2341.2
AS 2341.2
AS 2341.2
In house method
AS2341.2
In house method
-0.07
AS 2371.2
-0.39
1.90
In house method
AS2341.2
12
186.20
3.06
1.6%
177.7
200
22.3
Note: # indicates no response was returned
Note: § denotes an outlier (i.e. |z-score| ≥ 3)
-3
10A
-2
17
10B
36
16
0
25
-1
Lab code
20
11
21
Robust z-score
2
39
22
3
18
A8
Viscosity @ 60.0oC
1
A9
RTFOT Viscosity Change (%)
Lab
Code
10A
10B
11
16
17
20
21
25
36
39
Result
MU
166
147
173
171
165*
170
171
168
172
179
#
#
#
20%
6.4
6%
22.4
#
10
0 16
No. of Results
Median
Normalised IQR
Robust CV
Minimum
Maximum
Range
±
±
±
±
±
±
Robust
Z-Score
-1.16
-6.04 §
0.64
0.13
-1.41
-0.13
0.13
-0.64
0.39
2.18
Method / Technique
AS 2341.3
AS 2341.3
AS 2341-10 - RTFOT
AS 2341.10
AS 2341.2
AS2341.10
AS2341.2
AS 2341.10
AS2341.10
AS2341.10
10
170.5
3.9
2.3%
147
179
32
Note: # indicates no response was returned
§ denotes an outlier (i.e. |z-score| ≥ 3)
* indicates submitted results converted to percentage
A10
RTFOT Viscosity Change (%)
39
3
25
20
0
10A
17
-1
-2
-3
Lab code
21
16
11
36
1
10B
Robust z-score
2
A11
RTFOT Value after treatment (Pa S)
Lab
Code
10A
10B
11
16
17
20
21
25
36
Result
MU
294.6
267.5
324
317
299.8
318
319.4
313
318
#
#
#
20%
6.4
6%
22.4
#
10
No. of Results
Median
Normalised IQR
Robust CV
Minimum
Maximum
Range
±
±
±
±
±
Robust
Z-Score
-1.66
-3.67 §
0.52
0.00
-1.27
0.07
0.18
-0.30
0.07
Method / Technique
AS 2341.2
AS 2341.2
AS 2341-2
.AS 2341.2
AS 2341.2
In-house method
AS2341.2
AS 2341.2
In-house method
9
317.00
13.49
4.3%
267.5
324
56.5
Note: # indicates no response was returned
Note: § denotes an outlier (i.e. |z-score| ≥ 3)
A12
RTFOT Value after treatment (Pa S)
3
25
0
-2
-3
17
10A
-1
Lab code
21
36
20
16
11
1
10B
Robust z-score
2
A13
Lab Code
10A
10B
11
i) Shear rates for all
viscosities Tested
a) @ 135.0ºC and
b) @ 60.0ºC
a) 1130
b) 1.47
a) 1270
b) 1.42
#
ii) Partial filling
method or Total
filling method in the
determination of
density at 15.0ºC
iii) a) If CannonManning viscometer
used or
b) Asphalt Institute
viscometer (AI) and /
or
c) make and model
of rotational
viscometer
Partial
Cannon-manning
Partial
Cannon-manning
Partial
AI
12A
a) 34 sec-1
#
#
12B
a) 34 sec-1
#
#
15
a) Sp 21 50 rpm
#
#
a) 20.4s-1
b) 2.6 s-1
a) 39.6
b) 1.125s-1before
& 1.493s-1
a) 1024.6656
b) 6.3192
Partial
AI
Partial filling method
Asphalt Institute
Partial
Cannon-Manning
20
#
Partial
Haake viscobalance
used to determine
viscosities.
21
a) 9.75
b) 1.43 before
RTFOT 1.59 after
RTFOT
Partial
Cannon
22
b) 2.60
#
AI - size 100
Partial filling
AI for AS2341.2
(Cannon branded)
Cannon for
AS2341.3
Partial
No
Partial
Cannon-Manning
16
17
18
25
36
39
a) 0.562, 0.832
b) 1.010
a) 20s-1
b) 2.8s-1
a) 909.5
b) 6.9
Note: # indicates no response was returned
APPENDIX B
Homogeneity Testing
B1
HOMOGENEITY TESTING
Ten samples were selected at random and analysed in duplicate for Penetration at
25.0ºC (AS2341.12) and Viscosity @ 135.0ºC (AS2341.4). Statistical analysis of the
results indicated that no notable sample variability existed. Therefore, it was
concluded that any outlier results subsequently identified could not be attributed to
sample variability.
PTA HOMOGENIETY TESTING
Penetration at 25.00C
Viscosity at 135.00C
AS2341.12
AS2341.4
Sample No.
Results p.u.
Deviation Results Pa.s.
Deviation
51
72
-0.6993
0.385
-1.85185
46
72
-0.6993
0.378
0.00000
50
72
-0.6993
0.385
-1.85185
34
71
0.6993
0.380
-0.52910
42
71
0.6993
0.371
-1.85185
20
72
-0.6993
0.378
0.00000
38
72
-0.6993
0.374
1.05820
3
71
0.6993
0.373
1.32275
11
71
0.6993
0.382
-1.05820
9
71
0.6993
0.374
1.05820
Mean
%CV
71.5
0.7
0.3780
1.3%
Water bath temperature checked = 25.00C
Thermosel temperature checked = 135.00C
Note: Deviation lies within test method
requirements.
APPENDIX C
Instructions to Participants
and
Results Sheet
C1
PROFICIENCY TESTING AUSTRALIA
BITUMEN PROFICIENCY TESTING PROGRAM
ROUND 2
INSTRUCTIONS TO PARTICIPANTS
To ensure that results from this program can be analysed properly, participants are asked to
adhere carefully to the following instructions.
1.
2 x 800 ml samples labelled PTA Sample A and PTA Sample B are provided to each
laboratory.
2.
The following tests are to be conducted:
PTA Sample A:
Viscosity @ 1350C
Density at 15C (bottle)
Penetration 250C, 100g, 5s
PTA Sample B:
Vacuum Viscosity @ 600C (recommended to be tested before RTFOT)
RTFOT Viscosity Change (including the actual value after treatment)
3.
Participants can perform any or all of the above mentioned tests.
4.
If performing both ‘Sample B’ tests it is recommended to perform the Vacuum Viscosity
@ 600C test first.
5.
Participants should use the routine test methods which would normally be used to test
samples. (The Australian Standard method AS 2341 is the preferred method). Please
identify the method used on the Results Sheet.
6.
Laboratories are also requested to calculate and report an estimate of uncertainty of
measurement for each reported measurement result if possible. All estimates of
uncertainty of measurement must be given as a 95% confidence interval (coverage factor
k ≈ 2) and reported in ± reporting unit basis.
7.
The results for all determinations are to be recorded on the results sheet to the accuracy
and reporting basis indicated.
Laura Galbraith
Proficiency Testing Australia
PO Box 7507
SILVERWATER NSW 2128
Phone: 02 9736 8397
Fax: 02 9743 6664
Email: [email protected]
C2
PROFICIENCY TESTING AUSTRALIA
BITUMEN PROFICIENCY TESTING PROGRAM
ROUND 2
RESULTS SHEET
Lab Code
PTA SAMPLE A
TEST
(report to)
Result
MU ±
Method
Viscosity @ 135.00C
Density at 15.0C (bottle)
Penetration 25.00C, 100g, 5s
PTA SAMPLE B
TEST
(report to)
Result
MU ±
Method
Viscosity @ 60.00C
RTFOT Viscosity Change
(including the actual value after
treatment)
If rotational viscometer is used for any viscosity determination, please report make and model__________________
Also please report:
i) Shear rates for all viscosities tested: @ 135.0ºC_________________
@ 60.0ºC_________________
ii) Partial filling method or Total filling method in the determination of density at 15ºC___________________
iii) If Cannon-Manning viscometers or Asphalt Institute viscometers are used. ___________________
Date of tests:
Signature:
Send results by the 20 August 2010 to:
Laura Galbraith
Proficiency Testing Australia
PO Box 7507
SILVERWATER NSW 2128
Phone: 02 9736 8397
Fax: 02 9743 6664
Email: [email protected]
«Code»
----- End of report -----