Soil - Plasticity 2017 (72) PROFICIENCY TESTING PROGRAM REPORT

Transcription

1 Soil - Plasticity 2017 (72) PROFICIENCY TESTING PROGRAM REPORT Accredited for compliance with ISO/IEC Copyright: LabSmart Services Pty Ltd Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 1 of 38

2 Report This report is available on the LabSmart Services website. The issue of this proficiency report was authorised by Peter Young, Director, LabSmart Services Pty Ltd, July Contact Details Mobile: Fax: (03) Program Coordinator The program coordinator for this program was Peter Young, Director, LabSmart Services Pty Ltd. Contact Details Mobile: Fax: (03) Accredited Proficiency Testing Provider LabSmart Services is accredited by NATA to ISO/IEC 17043, Conformity assessment General requirements for proficiency testing. Accreditation number The accreditation provides additional assurance to participants of the quality and importance we place on our proficiency testing programs. LabSmart Services Please see our website for further details. Copyright This work is copyright. No part of this publication may be reproduced in any form, transmitted or stored in any repository (e.g. mechanical, digital, electronic or photographic) without prior written permission of LabSmart Services Pty Ltd. Please contact LabSmart Services Pty Ltd should you wish to reproduce any part of this report. Z-Score Summary Z-score summary for this program issued 16 June 2017 Amendment History Reports may be downloaded from the LabSmart Services website. Version 1 Issued 7 July 2017 Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 2 of 38

3 CONTENTS PAGE 1. Program Aim 4 2. Performance 2.1 Identified Outliers 2.2 Program Summary Technical Comment 3.1 Test Methods 3.2 Liquid limit & Plastic Limit 3.3 Plasticity Index 3.4 Linear Shrinkage 3.5 Reproducibility & Repeatability Sample A Statistics: Z- Scores & Graph 4.1 Liquid Limit 4.2 Plastic Limit 4.3 Plasticity Index 4.4 Linear Shrinkage Sample B Statistics: Z- Scores & Graph 5.1 Liquid Limit 5.2 Plastic Limit 5.3 Plasticity Index 5.4 Linear Shrinkage Program Information 6.1 Z-score Summary 6.2 Program Design 6.3 Sample Preparation 6.4 Packaging and Instructions 6.5 Quarantine 6.6 Sample Despatch 6.7 Homogeneity Testing 6.8 Participation 6.9 Statistics 6.10 Non-statistical outliers Test Results Summary 7.1 Test Results Summary Sample A 7.2 Test Results Summary Sample B Appendix A Appendix B Instructions for testers Results log Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 3 of 38

4 1. Program Aim The proficiency program was conducted in April/May 2017 with Twenty-nine participants from around Australia. The program involved the performance of the following four tests. AS Determination of the liquid limit of a soil Four point Casagrande method AS Determination of the plastic limit of a soil Standard Method AS Calculation of the plasticity index of a soil AS Determination of the linear shrinkage of a soil Standard Method Testing to the relevant sections of AS 1289 was preferred but other equivalent methods were accepted. The program provides confidence to the construction materials testing industry regarding the competency of participants (and the industry) to perform these tests. Each participant s performance is statistically assessed and used as a measure of competency relative to all those who participated. Other measures of performance are also used. This report has been prepared using robust statistics. Information regarding the conduct and design of the program can be found in section 6.9 Comprehensive technical comment (section 3) is provided to assist participants improve the overall performance of these tests. In addition, test data has been reviewed for consistency and additional feedback regarding aspects of the test are provided. A Z-score summary was issued to participants on the 16 June to facilitate early feedback on performance. 2. Performance 2.1 Identified Outliers There were 6 outliers identified across the tests performed. These were spread across 5 participants. This represented 17 of the 29 participants who returned results in the proficiency testing program (Table 2.1A). Participant s test results are tabulated in section 4 along with the robust statistics and a z-score graph. The z-score indicates how far away a participant is from the program s median value. A z-score of zero indicates a strong consensus with respect to all other participants and represents a very good outcome. The z-score graph gives a quick visual indication of how a result compares to others in the program. Outliers are where a z-score value is greater than 3 or less than -3. It is recommended that participants with outliers investigate their performance of the test. Participants with outliers are detailed in table 2.1A. Those participants with z-scores greater than 2 or less than -2 may wish to review their testing methodology. Only those approaching a z-score of 3 (i.e. outside ± 2.75) have been specifically identified in table 2.1A as feedback. Those shown in brackets are sufficiently close that these participants should review their result. Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 4 of 38

5 More detail on the robust statistics used can be found in section 6.9 Technical comment and feedback in section 3 is provided to assist participants investigate or review their results as well for those seeking to improve their testing performance. More detail on the robust statistics used can be found in section 6. Test Sample Units Investigate Review Liquid Limit Plastic Limit Plasticity Index Linear Shrinkage A - - B - - A D2 - B D2 - A Q5 - B P2, R2, V4 D2 A - - B - (D5) 2.2 Program Summary Table 2.1A Identified statistical outliers Overall a satisfactory level of testing was achieved by the majority (83) of the 29 participants. There were 5 participants identified as having a statistical outlier (17). Table 2.2A summarises the statistics from the proficiency program. The normalised IQR is an estimate of the standard deviation. The ranges shown for each test result exclude outliers. The variation in results observed were similar to previous proficiency testing programs. Laboratories and their clients need to be aware that as the magnitude of LL, PL and PI increases, the consistency between laboratories decreases. Overall the level of competency displayed by participants is within program expectations. Sample A Test Number of Results Units Median Normalised IQR CV Range Liquid Limit Plastic Limit Plasticity Index Linear Shrinkage Liquid Limit B Plastic Limit Plasticity Index Linear Shrinkage Table 2.2A Summary of program statistics. Results have been rounded. Range excludes outliers. Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 5 of 38

6 3.0 Technical Comment The performance by participants was good with a similar number of outliers to previous programs. The number of outliers was small. It is difficult to compare the spread or variation in results obtained because these are to some extent reflect the material properties and the characteristics of the program (see section 6.9.2). The variation in testing and other program statistics appeared to be about the same as previous plasticity programs. 3.1 Test Methods All tests were performed to Australian test methods unless denoted otherwise in section 7.1 & 7.2. Participants that indicated that different test methods had been used were U8, S3, T8, R2 and S6. Results from these participants gave satisfactory z-scores except for participant R2. In participant R2 s case in is unlikely that the outlier was due to a different method being used as participant S6 used the same methods and had no outliers. 3.2 Liquid Limit & Plastic Limit These two tests have a qualitative element as part of the test. Hence the results obtained are significantly affected by tester competency and material type. Also, some soil materials require more skill/experience to obtain reliable results than other materials. Because of the qualitative nature of the tests different proficiency testing programs with different soil materials and operator skills yield quite different outcomes in terms of the number of outliers and reproducibility of the test results. See Reproducibility & Repeatability below for more detail. Sample B, with larger PL and LL values, was more difficult for participants to obtain consistent results than sample A. This is reflected in the spread of results obtained. The variation for sample B was much larger than sample A (See table 2.2A). Considering both the homogeneity testing and participant results it is reasonable to infer that the variation observed for Sample A and B was due largely to operator abilities rather than the type of material itself. The variation in results observed were similar to those from previous LabSmart Services proficiency testing programs. However, it should be noted that the larger the spread (variation) of results the fewer outliers that may be able to be detected. In other words, if there were more results around the median value representing the most skilled participants then it may have resulted in more participants falling into the outlier region. There are too many aspects of these two tests to list here that, if incorrectly performed, can affect the outcome. As proficiency samples should be retained until the program report is issued it is recommended that those with outliers use Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 6 of 38

7 the retained material to repeat the test. It may help having a second, perhaps more experienced person; observe the test while you do so. Curing Approximately 61 of the participants used potable water and around 31 used distilled water. One participant used demineralised water and one tap water. The test method accepts most water types provided it is potable (i.e. safe to drink). Not all tap water fits this requirement. The method also indicates that some marginal potable water may influence test results. Apart from two (Z3 and T8) all participants used cure times greater than 48 hrs. There was a large range of curing times used. See section 7.1 & 7.2 for cure times used. 3.3 Plasticity Index The Plasticity Index is derived from both the Liquid Limit and Plastic Limit values. An outlier in either of these values does not automatically give rise to an outlier in the Plasticity Index value. Similarly, a Plasticity Index result may be an outlier without there being an outlier in either the Liquid Limit and Plastic Limit values. 3.4 Linear Shrinkage The variation in testing observed (Table 2.2A) for Linear Shrinkage matched previous proficiency programs. Participants (T8, R2 & S8) used moulds shorter than preferred by the test method but still within the test method requirements. The shorter moulds did not appear to affect the results in this instance. As indicated in the results tabulated in section 7 there are a range of description relating to the type of shrinkage observed. Participants were split about 38 to 62 between no change and an observable change. As noted in previous proficiency testing programs it would appear that the description of shrinkage is not a very reliable indicator. As this is a qualitative measure more guidance by the test method may be needed. 3.5 Reproducibility & Repeatability The two samples provided are examples of low and high plasticity. This program does not generate any repeatability estimates. It is expected that inhouse repeat testing (using the same sample, equipment and person) should lead to a decrease in the spread of results than the reproducibility estimates given by these proficiency testing programs. An indication of repeatability to be expected is given by the homogeneity test results (section 6.7). While the proficiency program provides an estimate of reproducibility it should be noted that it is indicative only. The reproducibility generated is affected by the material selected and the skill level of those in the program. Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 7 of 38

8 The Plasticity Index is a reasonable overall measure and results reflect the average skill level over most States. The standard deviation estimates (normalised IQR) shown for Plasticity Index (Table 2.2A) are generally within what has been historically observed in prior proficiency programs (by LSS and others). There is a trend between the PI value and the associated variation (NIQR). Increasing the magnitude of PI (and/or PL / LL) increases the NIQR (and range). The data is collect over many programs which causes the variation in results observed (see section 6.9.2). An example showing results from 2006 to 2017 for PI is shown below (Graph 3.1A, the 2017 results are circled). A linear trend line is also shown. As the value of the Plasticity Index increases the reproducibility between laboratories tends to increase Plasticity Index () vs. NIQR () NIQR () PI () Graph 3.1A Plasticity Index () verses NIQR () Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 8 of 38

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10 4.1 Sample A - Liquid Limit: Z - Scores Test Result Z Score N V F G Q D V P M Q U Z Y P R U C N V S D W F3 W7 J4 T S V Z R S J Statistic Value Test Result Number of results 29 Median 35.0 Median MU 0.46 First Quartile 33.6 Third Quartile 36.3 IQR 2.70 Normalised IQR 2.00 CV () 5.7 Minimum 30.6 () Maximum 39.0 () Range 8.4 () Z Score Note: A # indicates an outlier where the z-score obtained is either greater then 3 or less than -3. s for all participates are shown. The results column shows a blank entry for those participants that did not submit a result for this test. Minimum, Maximum and Range are calculated with outliers excluded, those in brackets include outliers. Particpants results that have been corrected are shown in green. Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 10 of 38

11 4.1 Sample A - Liquid Limit: Z - Score Graph V3 T8 Q5 U8 W5 S2 V4 U2 S3 G7 M5 Q9 N7 Y7 R5 V7 Z8 J3 D5 Z3 N3 S6 V8 P2 D2 P8 F9 C6 R Z-score Review Weak Consensus Strong Consensus Weak Consensus Review Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 11 of 38

12 4.2 Sample A - Plastic Limit: Z - Scores Test Result Z Score N V F G Q D V P M Q U Z Y P R U C N V S D # W F3 W7 J4 T S V Z R S J Statistic Value Test Result Number of results 29 Median 21.0 Median MU 0.34 First Quartile 20.0 Third Quartile 22.0 IQR 2.00 Normalised IQR 1.48 CV () 7.1 Minimum 17.6 (15.0) Maximum 24.0 (24.0) Range 6.4 (9.0) Z Score Note: A # indicates an outlier where the z-score obtained is either greater then 3 or less than -3. s for all participates are shown. The results column shows a blank entry for those participants that did not submit a result for this test. Minimum, Maximum and Range are calculated with outliers excluded, those in brackets include outliers. Particpants results that have been corrected are shown in green. Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 12 of 38

13 4.2 Sample A - Plastic Limit: Z - Score Graph V4 S3 V3 Z3 P2 U8 N3 V7 S6 Y7 R2 N7 Q9 U2 R5 W5 J3 G7 D5 P8 V8 M5 T8 S2 Z8 F9 C6 Q5 D Z-score Review Weak Consensus Strong Consensus Weak Consensus Review Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 13 of 38

14 4.3 Sample A - Plasticity Index: Z - Scores Test Result Z Score N V F G Q # D V P M Q U Z Y P R U C N V S D W F3 W7 J4 T S V Z R S J Statistic Value Test Result Number of results 29 Median 14.0 Median MU 0.52 First Quartile 13.0 Third Quartile 16.0 IQR 3.00 Normalised IQR 2.22 CV () 15.9 Minimum 9.4 (9.4) Maximum 18.2 (20.8) Range 8.8 (11.4) Z Score Note: A # indicates an outlier where the z-score obtained is either greater then 3 or less than -3. s for all participates are shown. The results column shows a blank entry for those participants that did not submit a result for this test. Minimum, Maximum and Range are calculated with outliers excluded, those in brackets include outliers. Particpants results that have been corrected are shown in green. Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 14 of 38

15 4.3 Sample A - Plasticity Index: Z - Score Graph Q5 T8 S2 D2 W5 M5 U8 V3 U2 Z8 G7 N7 Q9 R5 J3 D5 F9 V8 Y7 C6 V7 S3 V4 Z3 N3 S6 P8 P2 R Z-score Review Weak Consensus Strong Consensus Weak Consensus Review Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 15 of 38

16 4.4 Sample A - Linear Shrinkage: Z - Scores Test Result Z Score N V F G Q D V P M Q U Z Y P R U C N V S D W F3 W7 J4 T S V Z R S J Statistic Value Test Result Number of results 29 Median 7.0 Median MU 0.31 First Quartile 6.0 Third Quartile 7.8 IQR 1.80 Normalised IQR 1.33 CV () 19.1 Minimum 4.5 () Maximum 10.0 () Range 5.5 () Z Score Note: A # indicates an outlier where the z-score obtained is either greater then 3 or less than -3. s for all participates are shown. The results column shows a blank entry for those participants that did not submit a result for this test. Minimum, Maximum and Range are calculated with outliers excluded, those in brackets include outliers. Particpants results that have been corrected are shown in green. Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 16 of 38

17 4.4 Sample A - Linear Shrinkage: Z - Score Graph U8 P2 V3 D5 Q5 W5 S2 S6 T8 Z8 V8 M5 Q9 U2 V4 Y7 R5 S3 F9 C6 V7 J3 G7 R2 Z3 N3 D2 N7 P Z-score Review Weak Consensus Strong Consensus Weak Consensus Review Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 17 of 38

18 5.1 Sample B - Liquid Limit: Z - Scores Test Result Z Score N V F G Q D V P M Q U Z Y P R U C N V S D W F3 W7 J4 T S V Z R S J Statistic Value Test Result Number of results 29 Median 70.0 Median MU 1.08 First Quartile 65.7 Third Quartile 72.0 IQR 6.30 Normalised IQR 4.67 CV () 6.7 Minimum 60.3 () Maximum 79.0 () Range 18.7 () Z Score Note: A # indicates an outlier where the z-score obtained is either greater then 3 or less than -3. s for all participates are shown. The results column shows a blank entry for those participants that did not submit a result for this test. Minimum, Maximum and Range are calculated with outliers excluded, those in brackets include outliers. Particpants results that have been corrected are shown in green. Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 18 of 38

19 5.1 Sample B - Liquid Limit: Z - Score Graph S3 G7 T8 V3 U8 D2 M5 Z3 W5 D5 U2 Q9 R5 V7 S2 F9 V8 C6 P8 J3 Y7 Q5 N7 N3 Z8 S6 P2 R2 V Z-score Review Weak Consensus Strong Consensus Weak Consensus Review Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 19 of 38

20 5.2 Sample B - Plastic Limit: Z - Scores Test Result Z Score N V F G Q D V P M Q U Z Y P R U C N V S D # W F3 W7 J4 T S V Z R S J Statistic Value Test Result Number of results 29 Median 36.0 Median MU 0.69 First Quartile 33.0 Third Quartile 37.0 IQR 4.00 Normalised IQR 2.97 CV () 8.2 Minimum 27.0 (27.0) Maximum 40.0 (40.0) Range 13.0 (13.0) Z Score Note: A # indicates an outlier where the z-score obtained is either greater then 3 or less than -3. s for all participates are shown. The results column shows a blank entry for those participants that did not submit a result for this test. Minimum, Maximum and Range are calculated with outliers excluded, those in brackets include outliers. Particpants results that have been corrected are shown in green. Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 20 of 38

21 5.2 Sample B - Plastic Limit: Z - Score Graph S3 D5 P2 U8 R2 V4 F9 Z3 N3 V3 G7 P8 Y7 U2 W5 S6 V8 M5 Q9 R5 T8 N7 S2 V7 J3 C6 Z8 Q5 D Z-score Review Weak Consensus Strong Consensus Weak Consensus Review Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 21 of 38

22 5.3 Sample B - Plasticity Index: Z - Scores Test Result Z Score N V # F G Q D V P M Q U Z Y P # R U C N V S D W F3 W7 J4 T S V Z R # S J Statistic Value Test Result Number of results 29 Median 35.0 Median MU 0.86 First Quartile 32.0 Third Quartile 37.0 IQR 5.00 Normalised IQR 3.71 CV () 10.6 Minimum 26.0 (23.0) Maximum 46.0 (46.0) Range 20.0 (23.0) Z Score Note: A # indicates an outlier where the z-score obtained is either greater then 3 or less than -3. s for all participates are shown. The results column shows a blank entry for those participants that did not submit a result for this test. Minimum, Maximum and Range are calculated with outliers excluded, those in brackets include outliers. Particpants results that have been corrected are shown in green. Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 22 of 38

23 5.3 Sample B - Plasticity Index: Z - Score Graph D2 T8 G7 S3 V3 C6 V7 M5 S2 Q5 Q9 R5 U2 Z3 U8 W5 J3 V8 Z8 N7 F9 D5 P8 Y7 S6 N3 R2 P2 V Z-score Review Weak Consensus Strong Consensus Weak Consensus Review Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 23 of 38

24 5.4 Sample B - Linear Shrinkage: Z - Scores Test Result Z Score N V F G Q D V P M Q U Z Y P R U C N V S D W F3 W7 J4 T S V Z R S J Statistic Value Test Result Number of results 29 Median 7.0 Median MU 0.43 First Quartile 6.0 Third Quartile 8.5 IQR 2.50 Normalised IQR 1.85 CV () 26.5 Minimum 3.5 () Maximum 12.0 () Range 8.5 () Z Score Note: A # indicates an outlier where the z-score obtained is either greater then 3 or less than -3. s for all participates are shown. The results column shows a blank entry for those participants that did not submit a result for this test. Minimum, Maximum and Range are calculated with outliers excluded, those in brackets include outliers. Particpants results that have been corrected are shown in green. Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 24 of 38

25 5.4 Sample B - Linear Shrinkage: Z - Score Graph D5 Q5 U8 S2 V3 W5 P2 R5 D2 R2 G7 S6 F9 V8 M5 Q9 U2 Z8 J3 P8 N3 V4 T8 Z3 Y7 V7 S3 N7 C Z-score Review Weak Consensus Strong Consensus Weak Consensus Review Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 25 of 38

26 6.0 Program Information 6.1 Z-score Summary The proficiency program was conducted in April/May A Z-score Summary summary was issued on the 16 June A summary was e- mailed to participants. The summary is intended as an early indicator of participant performance. The proficiency testing program report supersedes the z score summary. Further information can be found in section 6.9 Statistics. 6.2 Program Design Design The program has been designed to cover some of the tests associated with soil classification. The preferred methods are shown below but other equivalent methods were also acceptable. AS Liquid Limit AS Plastic Limit AS Plasticity Index AS Liner Shrinkage The program is held annually. The test requires a minimum skill level. Adherence to the test method is essential for consistent test results. It is expected that the level of experience/skill needed to perform these tests will present a reasonable assessment of the overall competency of the tester and industry performance. The program was designed to provide technical feedback regarding performance as well as possible improvements in performance. Other considerations involving the design of the program are detailed below Selection of material used in the program The tests in this proficiency program are operator skill/experience dependant. In addition, certain types of materials require more knowledge to obtain consistent results than others. A processed naturally occurring material is used to reduce the variability associated with soils and to be able to select the plasticity required by the program. Different materials are selected for each program to mirror the range of materials encountered in practice. This program provides two samples that give results in the range that would be commonly tested by laboratories Role of proficiency testing The determination of outliers is an important task of this proficiency program. A secondary function is to provide feedback that can help those with outliers identify possible areas to investigate as well as assist all participants to improve. Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 26 of 38

27 In addition to the statistics, proficiency programs often obtain other information that is not normally available to a laboratory. It allows for a better understanding of the testing and can provide information that can lead to improvements in the testing process or test method. Proficiency testing enables participants to measure competency against others. It is also a measure of staff performance and the equipment used. Apart from measurement uncertainty it is the most useful tool a laboratory has in better understanding the performance of a test Participant assessment Assessment of each participant is based on a z-score that is related to the program consensus value (median). This is used to determine any statistical outliers. Compliance to proficiency program requirements including the correct calculation of results and adherence to program and test method requirements may also be used as part of the assessment process. Participants may also be asked to investigate any discrepancies detected with the paperwork submitted. See section 6.10 for further details Reporting of results - Significant figures The number of decimal places (significant figures) reported for a test has a bearing on the statistical analysis and therefore the interpretation of the results. There is a need to strike a balance between what is desirable from a statistical viewpoint while recognising how the results are used in practice. Too few decimal places (e.g. due to rounding) can cause an increase in the observed spread of results. Increasing the number of decimal places (with respect to normal reporting) can distort the observed spread of results compared to that encountered in actual practice. Large numbers of similar, rounded results can also cause a distortion in the analysis. For this program, it was decided that the benefits of using additional decimal places would not significantly improve the aim of the proficiency testing program. Participants results were analysed as received regardless of whether there were more or less significant figures than the number indicated by the test method Additional information requested This program requested additional information as detailed in section 7 that may not usually be reported. The additional information is however consistent with the performance of the test and the records the test method requires laboratories to maintain. The additional information is used to interpret participant s performance and assist with providing technical comment including feedback on outliers and possible participant improvement. Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 27 of 38

28 6.2.7 Data checks As often observed operator errors can occur in the result calculation process. Every participant s results were verified as reasonable. Plastic Limit and Plasticity Index calculations were recalculated. Checks however are only as accurate as the raw data supplied by each participant. These checks also help ensure that the data is comparable. Any inconsistencies identified during this process are identified as possible feedback for participant improvement. In some cases, inconsistences identified may need to be investigated by participants. 6.3 Sample Preparation Two different materials were selected for the program of a homogeneous appearance. The dried material was then mixed to ensure as far as possible a homogeneous material throughout. Samples were drawn from the two materials and double sealed in a Ziploc plastic bag to form lots (A & B). The sample quantities used were approximately 450g. Ten samples were drawn from the lot A packaged samples and ten from lot B. These were then tested for homogeneity. Samples from the two lots were randomly selected to form program samples (i.e. sample A & B). A unique program code was assigned to each program sample. Each participant received a program sample randomly drawn from the lot. 6.4 Packaging and Instructions Participants received one bubble wrapped package with two samples sealed in separate plastic bags marked Sample A and B. Instructions and a results log sheet were enclosed as detailed in Appendix A & B. Participants were instructed to test according to the nominated test method and report to the accuracy indicated on the results log sheet or test method. 6.5 Quarantine Samples meet quarantine requirements. 6.6 Sample Dispatch Samples were dispatched to participants on the 19 April 2017 using Toll Priority. Dispatched samples are tracked from despatch to delivery for each participant by LabSmart Services. Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 28 of 38

29 Liquid Limit Plastic Limit Plasticity Index Linear Shrinkage H H H H H H H H H H Mean SD Max Min Range CV () Table 6.7A Homogeneity results Sample A Liquid Limit Plastic Limit Plasticity Index Linear Shrinkage H H H H H H H H H Mean SD Max Min Range CV () Table 6.7B Homogeneity results Sample B Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 29 of 38

30 6.7 Homogeneity Testing Analysis of the homogeneity testing results (Table 6.7A and 6.7B) indicated that the variability associated with the proficiency samples was satisfactory. The average of the homogeneity samples also lies within 1 s.d of the participant s median value. The assessment of the homogeneity provides confidence that any outliers identified in the program represent statistically valid outliers. 6.8 Participation Thirty-two participants entered the program. The nominated date for participants to return their results was 12 May Approximately 20 of participants were late with returning results. Three participants did not return any results. 6.9 Statistics Z-Scores were calculated for each test and used to assess the variability of each participant relative to the consensus median. A corresponding z-score graph was produced for each test. The use of median and quartiles reduces the effect that outliers have on the statistics and other influences. As a consequence, z-scores provide a more realistic or robust method of assessment. Some results were reported by participants to more decimal places than requested as part of the proficiency program and by others to fewer decimal places. In all instances test results have been used as submitted by participants. A z-score is one way of measuring the degree of consensus with respect to the grouped test results. The z-scores in this report approximate standard deviations. For each test, a z-score graph is included. Use the graph to visually check statistically how you compare to other participants. The following bar (Figure 6.9A) is shown at the bottom of each graph. This helps to quickly visualize where each participant s result falls. Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 30 of 38

31 Review Weak Consensus Strong Consensus Weak Consensus Review Figure 6.9A Z-score interpretation bar For example: A strong consensus (i.e. agreement) means that your test result is close i.e. within 1 standard deviation of the median. A weak consensus means that your test result is satisfactory and is within 2 standard deviations of the median. If you have obtained a test result that is outside 2 standard deviations, then it may be worth reviewing your testing processes to ensure that all aspects are satisfactory. Only those obtaining a z-score approaching 3 (I.e. outside 2.75 range) have been highlighted in the report for review. If you have obtained a test result that is outside 3 standard deviations then you will need to investigate your testing processes to ensure that all aspects are satisfactory. For further details on the statistics used in this proficiency program can be obtained from LabSmart Services or download the Participant Guide from the LabSmart Services website Z-score Summary A Z-Scores Summary is issued soon after most results are received. It gives participants early feedback as to any program outliers. The summary is usually available on the LabSmart Services website up until the final report is issued. The final report supersedes the z-score summary. The final report contains detailed technical feedback regarding the performance of tests and revised z-scores. The inclusion of late results or corrections are at the discretion of the program coordinator. In some instances, this may change some of the z-scores slightly but generally the performance outcome remains the same. If there is any impact it will be discussed within section 6.1 of the report Comparing statistics from one program to another The statistics generated from one proficiency program are not usually comparable to those from another proficiency testing program. Only very general comparisons may be possible. The reason statistics from one program may not be compared to another is due to the range of variables that differ from one proficiency program to another. Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 31 of 38

32 These variables include: Type of material selected The number of participants Experience of participants Test methodology variations Equipment used Test methods used Experience of supervisors Range of organisations involved Program design and the statistics employed The program outcome represents a snap shot of the competency within the industry and hence provides an overview of the industry. The more participants involved in the program then the more representative the overview Measurement uncertainty The statistics detailed in this program do not replace the need for laboratories to separately calculated measurement uncertainties associated with each test when required by the client or NATA. The proficiency program does give information useful for calculating the MU and bench marking the MU calculated Metrological traceability The assigned median value used in this proficiency testing program is derived from participant performance and is not metrologically traceable Non-statistical Outliers One of the issues faced by proficiency testing providers is what to do with an incorrect result even if its z-score is satisfactory. In many cases they cannot be detected but still can have a significant impact on the statistics calculated. This can cause biased (or unfair) outcomes for other participants. To limit the effect of erroneous results have on a program additional information is requested to allow the main results to be recalculated. In some cases, results shown to be erroneous may be reject for inclusion in the program. If the result does not add any statistical bias it is left in the program. The result however is incorrect even though it may have a satisfactory z-score. To highlight that the participant needs to investigate erroneous results it is considered a non-statistical outlier. This may also be applied to non-compliance to program requirements e.g. incorrect reporting of results etc or incorrect partial calculations/data. Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 32 of 38

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34 7.1 Test Results Summary - Sample A Row N o Cure Time hr 1 2 Report 1 N Distilled 250 Cracking F Distilled No change 6 3 Q Potable 250 No change V Potable No change M Potable 250 Cracking Q Potable Cracking U Potable Cracking Z Distilled Cracking Y Distilled Cracking P Potable Cracking R Potable 254 Cracking U Demineralised Cracking C Distilled 250 No change N Potable 250 Cracking V Potable 250 Cracking S De-ionized 250 No change D2 4 days 32 4 days Potable 250 No change 5 18 W Distilled 125 No change F3 20 W7 21 J4 Cure Time hr Liquid Limit Plastic Limit Mould Plasticity Index Water Length mm Shrinkage Linear Shrinkage 22 T Potable No change S Potable 250 Curling V3 1 week 39 1 week Potable 250 No change 9 25 Z Potable 250 Cracking R Distilled No change S Potable Curling J Distilled Cracking V4 2 days /2 day Potable 250 Cracking G Potable 250 Cracking D Distilled Cracking P Tap 250 No change 4.5 NOTES: A blank or NR shows where result not completed or completed incorrectly. Blue - indicates a corrected result. Australian standard methods used unless shown otherwise above. Indicates Qild main roads methods used. Used AS Used AS Used AS Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 34 of 38

35 7.2 Test Results Summary - Sample B Row N o Cure Time hr 1 2 Report 1 N Distilled 250 No change F Distilled No change 7 3 Q Potable 250 No change V Potable Cracking M Potable 250 Cracking Q Potable Cracking U Potable Cracking Z Distilled Cracking Y Distilled No change P Potable No change R Potable 254 Cracking U Demineralised Curling C Distilled 250 Curling N Potable 250 No change V Potable 250 No change S De-ionized 250 Cracking D2 4 days 73 4 days Potable 250 No change 8 18 W Distilled 250 Cracking F3 20 W7 21 J4 Cure Time hr Liquid Limit Plastic Limit Plasticity Index 22 T Potable No change S Potable 250 Crumbling V3 1 week 76 1 week Potable 250 Cracking 9 25 Z Potable 250 Curling R Distilled Curling S Potable Curling J Distilled Curling V4 2 days /2 day Potable 250 Cracking G Potable 250 Curling D Distilled Cracking P Tap 250 No change 6.5 Water Mould Length mm Shrinkage Linear Shrinkage NOTES: A blank or NR shows where result not completed or completed incorrectly. Blue - indicates a corrected result. Australian standard methods used unless shown otherwise above. Indicates Qild main roads methods used. Used AS Used AS Used AS Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 35 of 38

36 LabSmart Services Appendix A Proficiency Testing Program Plasticity 2017 (72) INSTRUCTIONS FOR TESTER 1. Please check that the package you have received contains the following: Results Log Sealed plastic bag marked Sample A Sealed plastic bag marked Sample B Contact LabSmart Services if the bags are damaged or any item is missing. 2. When can I start testing? As soon as you have read these instructions carefully and your supervisor has indicated that you may do so. 3. How long do I have to do the testing? You need to have the results back to LabSmart Services by the 12 May Due to the possibility of segregation during transit mix each sample prior to testing. 5. Use AS 1289 test methods unless you are unable to do so. Complete those tests that you are able to perform. You may perform a test even if you are not NATA accredited for the test. 6. Conduct the following tests. AS Liquid limit 4 point Casagrande AS Plastic limit AS Plasticity index AS Linear shrinkage 7. A cure time of at least 48 hours is suggested. 8. For each test record the result on the enclosed Results Log. Report each result according to the reporting requirements of the test method. 9. Please include a copy of each 4 point Liquid Limit graph. 10. Have a query? Contact Peter Young on Fax or the Result Log to LabSmart Services by 12 May 2016 Fax: (03) OR dot@labsmartservices.com.au Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 36 of Appendix A Plasticity - Instructions V1.7 (72).docx

37 12. The Laboratory Manger or person responsible for checking should sign the log sheet to indicate that it has been checked. 13. If more than one technician is involved in the testing then please ensure that the laboratory s records indicate which technician did which sample. 14. It is recommended that the entire sample following testing be retained until the proficiency testing technical report for this program has been issued. 15. Please retain the completed Results Log as this contains your participation code that will identify your results in the technical report covering the proficiency testing program. It is also recommended that a copy of completed worksheets be kept with the results log in your proficiency file. 16. Proficiency testing can also form part of a laboratories training records for the technician who performed the test. Thank you for participating in this proficiency program. Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 37 of Appendix A Plasticity - Instructions V1.7 (72).docx

38 LabSmart Services Appendix B Plasticity Proficiency Testing Program 2017 (72) RESULTS LOG For xxxxx Participation : xx Please fax or the completed results log by 12 MAY dot@labsmartservices.com.au Fax: (03) TEST METHOD Sample A RESULTS Sample B Date received Condition of sample received Colour of sample AS (Liquid Limit) Cure Time Please attach the 4 point Liquid Limit graph for each sample to results sheet. Please attach the 4 point Liquid Limit graph for each sample to results sheet. Results AS (Plastic Limit) AS (Plasticity Index) AS (Linear Shrinkage) Cure Time Results Results Length of shrinkage mould (mm) Results 1 2 Reported 1 2 Reported Describe Shrinkage i.e. curling, cracking, crumbling, no change Type of water used (e.g. tap, distilled etc) Name of tester Date tested COMMENTS: Supervisor Name (Please Print) Signature Date In signing the above I acknowledge that the above results are approved and have been checked. I will also ensure that the results are kept confidential both internal and external to the laboratory until the issue of the final technical report covering this program. Thank you for participating. Please retain a copy of this sheet for your records. Copyright: LabSmart Services Pty Ltd Issued: 7/7/2017 Page 38 of Appendix B Plasticity - Results Log V1.6 (72).docx)