CBR - 2017 (74) PROFICIENCY TESTING PROGRAM REPORT · This report has been prepared using robust...

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CBR - 2017 (74)

PROFICIENCY TESTING

PROGRAM REPORT

Accredited for compliance with ISO/IEC 17043

Copyright: LabSmart Services Pty Ltd

CBR Proficiency Testing Program - 2017(74)

Copyright: LabSmart Services Pty Ltd Issued - 5 February 2018 of 60

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, Febuary 2018. Contact Details

Email: [email protected] Mobile: 0432 767 706 Fax: (03) 8888 4987

Program Coordinator The program coordinator for this program was Peter Young, Director, LabSmart Services Pty Ltd. Contact Details

Email: [email protected] Mobile: 0432 767 706 Fax: (03) 8888 4987

Accredited Proficiency Testing Provider LabSmart Services is accredited by NATA to ISO/IEC 17043, Conformity assessment – General requirements for proficiency testing. Accreditation number 19235. 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.

www.labsmartservices.com.au

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 30 November 2017

Amendment History Reports may be downloaded from the LabSmart Services website.

Version 1 – Issued 5 February 2018



CONTENTS PAGE

1. Program Aim

5

2. Performance

2.1 Performance assessment 2.2 Identified outliers 2.3 Focus on improvement 2.4 Program summary

5 5 6 8 10

3. Technical Comment

3.1 General performance

3.1.1 Supply of program information 3.1.2 Errors

3.2 Statistics

3.2.1 Accuracy of data 3.2.2 Variation in CBR results 3.2.3 Set s.d limit 3.2.4 Repeatability

3.3 CBR results

3.3.1 Participant assessment 3.3.2 CBR results 3.3.3 Identification of inconsistencies and errors 3.3.4 Repeatability

3.4 Measurement uncertainty 3.5 Direct influences

3.5.1 Load cell 3.5.2 Seating load 3.5.3 Penetration rate 3.5.4 Test (penetration / load) data 3.5.5 Accuracy of the graph prepared 3.5.6 Zero-point correction 3.5.7 Rounding

3.6 Indirect influences

3.6.1 Pre-compaction curing 3.6.2 CBR compaction 3.6.3 OMC & MDD 3.6.4 LDR & LMR

3.7 Australian Standard CBR Test method

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11 11

12

12 12 12 13

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13 14 14 15

16

16

16 17 18 19 20 21 21

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22 23 24 25

27

4. Statistics: Z-Scores & Graph

4.1 CBR Z-scores : Sample A 4.2 CBR Z-scores : Sample B

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28 30



5. Program Information

5.1 Z-score summary 5.2 Program design

5.2.1 Design 5.2.2 Selection of material for program 5.2.3 OMC & MDD 5.2.4 Role of proficiency testing 5.2.5 Participant assessment 5.2.6 Reporting of results – significant figures 5.2.7 Additional information requested 5.2.8 Data checks

5.3 Sample preparation 5.4 Packaging and instructions 5.5 Quarantine 5.6 Sample dispatch 5.7 Homogeneity testing 5.8 Participation 5.9 Statistics

5.9.1 Z-score Summary 5.9.2 Comparing statistics from one program to another 5.9.3 Measurement uncertainty 5.9.4 Metrological traceability

5.10 Non-statistical outliers

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32 32

32 32 32 33 33 33 34 34

34 35 35 35 35 35 35

37 37 38 38

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6. Participants’ Test Results

39

Appendix A Instructions for testers

Appendix B Results log

Appendix C Graph example Appendix D CBR Measurement Uncertainty

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55

58

59



1. Program Aim

The proficiency program was conducted in September/October 2017 with participants

throughout Australia. The program involved the performance of:

AS 1289.6.1.1 (2014) – Determination of the California Bearing Ratio of a soil –

Standard laboratory method for a remoulded specimen.

The program provides feedback and confidence to the construction materials testing

industry regarding the competency of participants (and the industry) to perform this

test. 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. In addition, test data has been

reviewed for consistency and additional feedback regarding aspects of the test are

provided.

Comprehensive technical comment is provided to assist participants improve the

overall performance of this test (Section 3).

Information regarding the conduct and design of the program etc. can be found under

section 5.

2. Performance

2.1 Performance assessment The CBR test is a complex test from a measurement uncertainty perspective despite its apparent technical simplicity. Unfortunately, the CBR test method does not provide guidance about some aspects of the test such as repeatability or reproducibility. There also appears a lack of guidance on both the performance and the interpretation of the test within the industry. The range of test results obtained in a proficiency program, for any given sample, has been far wider than is generally acceptable to the industry. This adds to the difficulty in interpreting the outcome of CBR proficiency testing programs. In discussing the outcome of this program, the following have broadly been used to determine outliers and areas for investigation/review. Statistical outliers • Z-scores based on submitted CBR results

Non-statistical outliers • Identification of inconsistences, non-adherence to test method and errors

• Accuracy of calculations/graphing

• Repeatability



Proficiency testing providers are obligated under their accreditation standard to remove results known to be incorrect or where a participant has not followed the test method including adherence to prescribed limits. Not providing all data requested, particularly where it is used to assess the validity of the results obtained (e.g. compaction, MC) is also a valid reason to reject a CBR result. These matters are not ‘black & white’ but require some interpretation as to each components importance. Keeping results that may be suspect in the statistical pool may distort the statistical outcome. However, if all the results found to be inaccurate or not meet the test method etc. were rejected from this program the pool of results would be significantly decreased. A balance must be struck. This is discussed in more detail under technical comment (section 3.1 & 3.2).

2.2 Identified outliers

In most proficiency testing programs the identification of outliers is relatively straight

forward. This is not the situation with CBR testing due to the large range in CBR

results obtained.

Industry has expressed concerns that from an engineering “End User” perspective that

such large variations in CBR results are impractical. It is also undesirable from a

laboratory testing perspective.

As has been indicated in previous proficiency programs, it is the middle 50% of

participants results that is far larger than it should be. It is this group of results

therefore that is of primary interest when considering ways in which to reduce the

spread of results.

Participants with statistical outliers, departure from the test method or errors

(Investigate) and those with significant departures compared to other participants

(Review) are summarised in table 2.2A.

Participants where there is a concern regarding accuracy of the results are requested

to investigate their submissions. Others have been identified as able to benefit from

reviewing their submissions where it is felt the quality of testing may be improved.

In table 2.2A there are no participants listed e.g. ‘penetration rate’ and ‘test data’ under

some sections This is not because there are no concerns identified only that the test

method does not necessarily identify, address or quantify all issues affecting the

accuracy/precision for this test.

The more times a participant’s code appears in the table 2.2A the greater the need for

follow up.



Aspect of testing Section Investigate Review

Sample A Sample B Sample A Sample B

CBR results 3.3.2 B5 B5, G9 L2, R4, G9,

C6 P4, G9, C6

Identification of inconsistences and errors

3.3.3 D7, R4,

G9 R4, G9 - -

Repeatability 3.3.4 - B5, D6, L2, Y5, C5, R4,

Z6, D5, M2, P7

Load cell 3.5.1 - Z6

Seating load 3.5.2 - All participants except W2, R3, V6, Q8, P7

Seating load set to zero 3.5.2 U2, U9, F7 -

Penetration rate 3.5.3 - -

Test data (Load /Penetration

points) 3.5.4 - -

Accuracy of graph 3.5.5 B5, G9, V6, B9, F7, C6,

P7 -

Zero-point correction 3.5.6 - B5, G9, V6, B9, F7, C6,

P7

Rounding 3.5.7 - -

Pre-compaction curing 3.6.1 W2, G9, Z6 D6, Y8, L2, J4, D7, W2,

R4, G9, G5, W6

CBR compaction 3.6.2 -

Y5, C5, P4, S2, Q9, M6, Y3, Q8, L6, G5, W6, Q2, B9, F7,

P7, R3, U2

V2, Y5, C5, P4, S2, Q9, M6, Y3, U2, Q8, L6, G5,

W6, Q2, B9, F7, P7

OMC & MDD 3.6.3 - -

LDR 3.6.4 P4, G9 P4 - -

LMR 3.6.4 W2, G9,

Z6 D6, L2, G9,

Z6 - -

One or more inconsistent results or calculations

3.6.4

R8, W2, R4, G9, L2, P4,

Z6, F7, E3

B4, R4, P4, D5, W2,

G9, Z6, Q2, F7

- -

Table 2.2A – Participants identified where investigation or review follow up is warranted.



2.3 Focus on improvement Have laboratories improved? The answer is yes. The standard of CBR testing has

improved enormously over the last 8 years. Much of this can be attributed to

laboratories being prepared to participate in PT programs and being prepared to

improve on existing laboratory practices (e.g. move away from hand graphs to

computer generated graphs etc.).

To the many participants and organisations who have participated “well done”

and “thank you” for your participation.

The programs have had large numbers of participants which means the conclusions that have been drawn are therefore far more reliable. The coefficient of variation (CV) over this time has been around 30 % whereas this program has a CV of 21%. Note that the ‘gold’ highlighting shows programs conducted to the current 2014 test method. It shows that the spread (variation) in CBR test results are heading in the right direction.

Year Program Median CV

2017 74 52 21

2016 67 155 21

2015 59 140 20

2014 54 74 31

2013 46 37 29

2012 37 44 20

2011 48 61 35

2009 16 30 32

Table 2.3A Comparison of CBR program results for the last nine years

Why is the middle 50% important? At present the spread of results is extremely large and affects the repeatability and reproducibility of the test. In other words, if it is too large the CBR results become meaningless. Based on this national proficiency program and others the CBR results may appear of limited value to the end user. However, if put in context as to where the CBR results are used the situation may not be so bad. On a regional basis, where the CBR results are used, there may be much closer agreement. This may be due to similar training or better overseeing by a technical body etc. (e.g. Road Authorities) Has the CBR test results always been subject to the same large spread in results? Most likely it has. It may have been that it just was either not observed due to no national PT programs or seemed unimportant at the time. There is nothing in the test method that has changed substantially over the years to cause a change in the spread of results obtained. Staff are no better or worse trained then previously.



What has changed over the last 50 years however is how results are interpreted and used. Road Authorities did much of the road construction work and testing so CBR results were basically in-house. Results were generally compared amongst those trained the same way using similar or same equipment. There was not the proliferation of small testing laboratories back then or the need to compare results from one State to another. National CBR proficiency programs for CBR were either not run or if so very infrequent. Today there are laboratories with quite diverse views on the CBR method and using quite different equipment. The test method allows considerable latitude in the performance of the test. It is not unexpected that the variation across Australia is as large as it is. How can improving the accuracy with which the test is performed help. It was hoped that improving the accuracy of testing would significantly reduce the spread in results shown. This program and others have shown that this may not be the case. The accuracy of many of the test results was shown that they could be improved but it did not necessarily lead to a significant reduction in the spread of the middle 50% of participants. Accuracy of testing still needs to be improved and most laboratories are trying to do this. Graphing has a significant impact on the overall accuracy achieved. Section 3.5 focus on those aspects most directly affecting CBR accuracy. What aspects of the test affect the outcome indirectly? The test method puts limits on the indirect aspects of the test such as moisture, compaction, LDR and LMR etc. It would appear at present, that while these are important, the control of them and how it affects the outcome is difficult to predict or quantify. Most cannot be examined in isolation nor is it clear how they interact. See section 3.6. Past programs indicate that removing those results that did not comply with the limits placed by the test method did not necessarily lead to an improvement in the spread of results. Can changes to the test method help? The last change to the test method has seen a significant reduction to the spread of results obtained. Based on the technical comments (section 3.7) it appears that while incremental improvements are possible any major improvement may need a substantial rethink of the test method. How can laboratories improve? Proficiency testing programs that provide technical feedback assist laboratories to improve. The technical comment detailed in section 3 has this in mind and is aimed at helping laboratories to have a greater understanding of the test. A reduction in testing errors, better graphing and supervisor checking will greatly improve the accuracy of testing.



2.4 Program Summary Based on LabSmart Services programs there has been an observable improvement in CBR testing over the last nine years as measured by the coefficient of variation (CV). The last three programs have levelled out at a CV of 21%. Laboratories have done very well with fewer outliers compared to previous programs. A very good outcome and within the expectations of the test method. Previous proficiency programs have highlighted the need to reduce the variation shown by the middle 50 % of participants. The technical comment for this program indicates that there are ways to reduce this slightly, but it may be that this spread is just reflecting the accuracy of this test. There are several improvements that laboratories can make to improve the accuracy of their individual results. Improvements in repeatability are also needed. The program identified those aspects of the test that most affect accuracy (direct influences) and those aspects of the test that have less influence (indirect). There are aspects of the test method such as graphing and zero correction where further guidance is needed for the industry. The CBR graph would appear to be the only way of checking the validity of the results obtained. In most cases the graphs prepared do not adequately fulfil this function. A reduction in testing errors, better graphing and supervisor checking will greatly improve the accuracy of CBR testing. Improvements to the test method, by better defining the test process (e.g. graphing), limits and expected outcomes would also significantly improve the accuracy of the test. This proficiency program provides increased understanding of current test practices and potential sources of variation. It also allows monitoring of improvements in testing and provides the opportunity for participants to improve their competency. A summary of the program statistics is shown in Table 2.4A.

Statistic CBR A CBR B

Number of participants 41 40

Median 52.0 54.6

Normalized IQR 11.6 11.2

Minimum* 21 27

Maximum* 75 69

Range* 54 42

CV (%) 22 21

Table 2.4A Summary of statistics for the CBR program. Some results have been rounded. *Min, Max & Range are with outliers excluded.



3.0 Technical comment 3.1 General performance Proficiency program participants are expected to comply with the requirements of the program and meet basic laboratory standards. General performance covers those aspects of laboratory operations that are expected to be performed as part of good laboratory practice and in keeping with NATA accreditation. Some aspects that are particularly relevant for this program are:

➢ Supervision of testing

➢ Following the test method

➢ Following proficiency testing instructions

➢ Correctly filling out paperwork i.e. PT log sheet

➢ Checking of results

➢ Free of errors i.e. calculations correct

➢ Reality check of results i.e. does it fit the type of material submitted

Compared to earlier CBR proficiency testing programs there has been significant improvement in most of the above areas. However as detailed in subsequent sections there is still a considerable way to go to improve the accuracy of testing. It also raises the question that if participants are not meeting the above basic requirements then what other omissions or errors are occurring during testing that remain undetected. 3.1.1 Supply of program information

Most participants supplied all the testing details requested. This information is used

to validate the results received and to provide the feedback given in the following

sections.

Participants are always welcome to contact the program coordinator if they require

further explanation as to what information is required or how to proceed.

Participant results can be rejected if they do not conform to the program requirements.

3.1.2 Errors

Errors may arise from several sources, an incorrect calculation, transcription error, wrong methodology used, not following the test method etc. Many of the comments in the following sections relate to errors. Although some of these may have only a small impact they do accumulate and should not occur. Others can have a large impact such as incorrect graphing technique and zero correction.



Reduction in the number of errors detected in this program would significantly improve

the credibility of CBR testing and possibly reduce the variation (spread) in CBR results

obtained.

3.2 Statistics

The use of statistics are a very useful and practical means of analysing test data.

Those that use statistics everyday know the limitations and shortcomings of their use.

Below are some aspects that affect statistical outcomes.

3.2.1 Accuracy of data

If the test data is in error, then any statistics calculated may also be in error. Any

interpretations made, based on the statistics, may therefore also be in error. Most

proficiency programs can handle a few inaccurate results without any concern about

the validity (accuracy and precision of the outcome) of the program. Most of the

technical comment concerns the accuracy of the CBR test results. The number of test

results that are questionable does raise significant concern about the validity of CBR

test results.

3.2.2 Variation in CBR results

Often proficiency testing programs tend to focus on feedback concerning those with results that seem either too high or too low (outliers). While this is important sometimes other areas need scrutiny. The fundamental issue with CBR test results is that there is too large a spread shown by the middle 50% of participants. Within this group the results are too spread out. This means that identifying accurately a median value or outliers may be seriously compromised. It seriously affects the accuracy and precision of the test results. Without improvement or better understanding of CBR test results the credibility of the

test may be at risk.

3.2.3 “Set s.d limit”

In previous CBR proficiency programs the z-score statistics have been recalculated

using a “Set s.d limit” or “Target s.d”. The purpose of which was to bring the variation

(spread) in results back to something useful to geotechnical engineers and others in

the industry. It appears as a very practical way of approaching the problem.

There is no reason however to suspect that, based on the outcome of this program,

or other programs that any result within the middle 50% is better than any another

result from the middle 50%. The “Set s.d limit” outcome then does not give much

useful information.



If the accuracy of many test results is questionable along with the median value, then

results may lie above or below any ‘set limits’. It does not identify problems or

inaccurate results, worse, it could indicate results as being satisfactory when they may

not be.

The “set limits” is therefore no longer used in these PT programs.

3.2.4 Repeatability

If the spread of results for duplicate participant results and between laboratories

(participants) is large, it is hard to arrive at a sensible repeatability and reproducibility

estimate. The accuracy of the results also has a large impact. See section 3.3.4 for

more detail on repeatability. Future programs may be able to provide better estimates

of repeatability once the spread of results is further reduced.

3.3 CBR Results

3.3.1 Participant assessment

Participant performance has been assessed based on:

Statistical outliers • Z-scores based on submitted CBR results

Non-statistical outliers • Identification of inconsistences, non-adherence to test method and errors

• Accuracy of calculations/graphing

• Repeatability

Participants need to be aware that the program coordinator performing the checks

may not have access to the full set of results for each participant (e.g. significant

figures etc.). This can sometimes cause differences between what the participant has

calculated and what the program coordinator calculates.

Also, due to the large amount of data associated with this program it is entirely possible

that the coordinator may not have recalculated some participants results correctly

although considerable effect is made to prevent this from occurring.

Participants are asked to “investigate” matters that are statistical outliers and errors.

Where the test method has not been followed or are outside the limits set in the test

method these also need to be investigated as non-statistical outliers.

Other maters identified are shown as “Review”. These are matters that would help

improve testing and it most cases would be considered outside normal testing

parameters. It is sometimes difficult to determine as the test method often does not

provide sufficient guidance.



3.3.2 CBR results

Z-scores and associated statistics were calculated on the CBR results as submitted

and are detailed in section 4.1 and 4.2. The following statistical outliers were identified

as detailed in table 3.3.2A. Participants with z-scores around 2 or -2 should review

the results obtained.

Sample A Sample B

Investigate Review Investigate Review

B5 L2, R4, G9, C6 B5, G9 P4, C6

Table 3.3.2A Participants identified as having statistical outliers in the program

For the CBR test the spread of results is very large over the middle 50% of participants.

Both sample A and B were the same material.

3.3.3 Identification of inconsistences and errors

There are many steps within the conduct of the test (methodology) that can become a

source of error or where inconsistencies can occur. As well there are limits posed by

the test method itself that may also contribute. For example, compaction and moisture

content.

To better understand the influence that these sources have on the variation of the test

they have been broken up into those that directly affect the CBR result and can be

measured and those where the impact on the CBR result cannot be easily measured

i.e. indirect. See section 3.4 for more information on determining direct and indirect

influences.

Direct influences generally involve participant errors or inconsistencies in testing.

These are discussed in more detail in section 3.5. Indirect influences generally involve

non – compliance to the test method requirements or limits. These are discussed in

section 3.6.

The use of a detailed CBR graph is a quick and reliable means of checking results. A

rough mathematical check was undertaken by the program coordinator for all

participants. Those with significant differences were regraphed and the CBR

recalculated.

The CBR result for some participants was either missing, abnormal or had not been

calculated correctly. The results for these participants were amended and are shown

in green in section 4.1 and 4.2. These participants (table 3.3.3A) need to investigate

the results report.



Investigate

Sample A B

Codes D7, R4, G9 R4, G9

Table 3.3.3A Participants identified as having non-statistical outliers in the program

3.3.4 Repeatability

The spread of results was much larger in earlier programs. Previously it was felt that

investigating methodology yielded better information then testing duplicate samples

would have. The test method was revised in 2014 and addressed some shortcomings

in relation to the compaction process. This led to changes in methodology for some

laboratories and improvement in the CBR variation. See table 2.3A

The new test method has now had a reasonable period to ‘bed in’. As consequence

if was felt that it was appropriate to use duplicate samples for the last two programs to

try and measure repeatability.

Unfortunately, the large spread in results obtained for reproducibility also affects the

repeatability outcome. The number of participants where the CBR value calculated by

participants was shown to be inaccurate is quite high. Considering both these factors

makes the statistical evaluation of repeatability questionable.

An alternative approach would be to use the homogeneity data as an estimate.

However, this may also be a shaky estimate. The precision may be good (same

machine and pace rate) but it is unknown if the accuracy is good or poor. The

homogeneity results were within 1 s.d so it provides a reasonable estimate.

The homogeneity results gave a s.d of 8% and CV of 16%. Based on these values

the the following participants had results (A & B) that differed by more than 8% and

should be reviewed.

B5, D6, L2, Y5, C5, R4, Z6, D5, M2, P7

Those shown in bold had differences greater than 16%.



3.4 Measurement Uncertainty

Measurement uncertainty can be useful as a tool to examine the effect of test

methodology has on the final CBR result. Appendix D discusses this in more detail.

It is useful to split up aspects of the test into two categories.

Direct uncertainty components (section 3.5) can be measured or estimated.

Testing can be improved by reducing these and strict adherence to the test method.

➢ Accuracy of the load cell

➢ Accuracy of seating load

➢ Accuracy of penetration

➢ Accuracy of the rate of penetration

➢ Accuracy of recording force readings

➢ Number of data points selected

➢ Accuracy of the graph prepared

➢ Accuracy of the zero correction

➢ Rounding of results

Indirect uncertainty components (section 3.6) cannot be improved easily. Test

variation is minimised by strict adherence to the test method.

➢ OMC & MDD

➢ Moisture content

➢ LDR & LMR

➢ Curing of sample


➢ Compaction i.e. layer thickness,

compaction pattern, number of blows,

achievement of LDR & LMR

➢ Soil characteristics

3.5 Direct Influences

The following sections cover many aspects of test methodology. From previous

programs it has been noted that even with corrections resulting from re-graphed data

and using unrounded results if has only a marginal effect on the middle 50% of

participants. In other words, the corrections tend to be random with some corrected

CBR values increasing while others decrease.

Overall it suggests that while the accuracy of testing can and should be improved there

may be little change to the overall spread of results obtained for the CBR test.

3.5.1 Load cell

In section 6 the load values are shown for each participant. Some laboratories used

more data points than requested (great to see) but these have not been included in

the tabulated results.

Most participants in this program used load cells with three participants (B5, G9 & U2)

that used load rings. Most load cells were calibrated to ‘Class ‘A’ or a combination

e.g. A/B/C. Participants generally used a 50 kN load device with CBR values occurring

around 8 kN. (See Table 3.5.1A)



Load Cell Capacity (kN) Participant

50 Majority

40 V6, D5,

90 J3

100 P4, B8

1500 Z6

Table 3.5.1A Summary load cell capacity used in the program

Participants should be aware that as the cell capacity increases the accuracy may

decrease in some cases. Selection of the correct load cell capacity is dependent on

the experience of the laboratory and where possible prior knowledge of the material

to be tested.

Unfortunately, due to the large range of CBR results possible from participants,

warning cannot be given by the program organisers prior to testing.

If a load cell does not have sufficient capacity during testing it is important that testing

be stopped on approach to the maximum capacity of the load cell. Exceeding the

capacity of a load cell or ring can cause permanent damage.

Another consideration is the resolution at the lower end of the load scale to accurately

measure the seating load. For load cells used in this program that are on the larger

side (e.g. 50kN) it may be difficult to accurately measure small loads.

Often this is not a lack in ability of the load cell but a reflection of the normal calibration

practise where the calibration may not extend to the low load values required for

seating loads or low CBR values. Laboratories may need to request calibration

facilities, where possible, to specifically cover the seating loads required when

undertaking the load cell calibration.

Participant Z6 should review the use of a 1500 kN cell.

3.5.2 Seating load

The test method requires that the least amount of force be used for the seating load.

It is important that the piston is in contact with a stable surface. The seating load is

considered the ‘zero point’ from which the load values and penetration commence.

In this program the CBR was greater than 30% and a seating load of 250 N should

have been used. Only five participants (W2, R3, V6, Q8 & P7) or 12% used the correct



seating load. The test method indicates that 50N should be used for CBRs less than

30%. Very few used this seating load.

The test method requires laboratories to have tested the material before to know the

expected CBR value or be able to select the seating load based on experience. It is

perhaps a weakness of the method as much as any failing on the part of the tester.

At high CBRs the seating load has only minimal effect on the CBR obtained but does

influence where the penetration points fall. For this type of material any effect of

incorrect assignment of the zero penetration is usually cancelled out with the zero-

point correction offset if performed correctly.

Setting the seating load to zero was done by most participants except (U2, U9 & F7).

Not setting ‘back to zero’ again can lead to an inaccuracy in the load scale creating an

offset.

However, errors in both processes (seating load applied and resetting back to zero)

may influence the CBR. An error in penetration of ± 0.25mm could lead to a change

of ± 3.3% CBR. This may not seem much but in the rounding process when reporting

this may cause a difference of 10%.

3.5.3 Penetration rate

The test method indicates that the machine used must be capable of “….forcing the

penetration piston into the specimen at uniform (not pulsating) rate of 1.0± 0.2 mm/min

during the complete test….”. The penetration rate had in the past not been routinely

checked until NATA in recent years required it be checked every two years.

It is not entirely clear, based on input from participants, if the standard means an

‘average rate’ or if it means it must be met at ‘all times’. If it is taken as an average

rate then theoretically you could have half the penetration at 0.5 mm/min and the other

half at 1.5 mm/min and still arrive at the average rate of 1.0 mm/min.

For ‘hand’ operated devices it is hard to check other than an overall average. A

motorised platform was used by most participants with four participants (Z6, S2, C5,

W2) using a hand operated unit.

With load cell units, they usually allow the rate to be checked as you go on a ‘per 0.5

mm of travel’ etc. This can be done on a ‘test by test’ basis so is a very good record

of meeting the requirements of the standard.

In previous programs the rate was requested with most participants reporting the test

method requirement rather than the actual rate achieved. For this program more

detailed information was requested from participants e.g. average, minimum and

maximum rates achieved.



Around 50% of participants accurately completed this section of the program. Those

that did provided the information all meet the requirements of the test method.

The penetration rate is linked to the slope of the load/penetration curve. It is therefore

significant in determining the CBR and hence the set limits placed on the rate of travel

by the test method.

3.5.4 Test (penetration / load) data

The number of penetration points selected is extremely important. All participants

recorded the requested additional load/penetration data and some recorded more. A

very good outcome.

The test method specifies a minimum data set (0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 4.0, 5.0, 7.5,

10.0 and 12.5 mm penetrations).

The key word in the test method is “at least”. In other words if you know the material

well (i.e. have a CBR history of the material) then you should be able to use fewer

points otherwise you need to record loads at more points.

Additional data points are needed to:

➢ Allow for the discount of an abnormal data value ➢ Have sufficient points left so that the discounting of a point does not

compromise the test result ➢ Have sufficient points to fit a straight line and a curve ➢ Have sufficient points above the straight section of the graph. ➢ Have sufficient points to be able to tell that you have an abnormal data point

3.5.4A Load / penetration graph for participant B5, Sample A

A ‘suspect’ data point (i.e. circled data point) is shown in Table 3.5.4A. If the data

point at 6mm is removed it can have a significant effect on the CBR obtained. With

y = 21.021x4 - 371.48x3 + 2231.6x2 - 1629.2x + 268.3R² = 0.9974

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

50,000

0 1 2 3 4 5 6 7 8 9 10 11 12

Ap

plie

d L

oad

(N

)

Penetration (mm)

CBR Graph for Participant B5Data Values



the suspect data point CBR is 92% but with the data point removed it is 102%. This

is a difference of 10 between the two possible CBR results.

Such differences contribute to the spread of results observed.

It is evident also that two few data points can have a measurable difference on the

result that is obtained as much as suspect data. Greater confidence in the result and

accuracy is obtained when more points are taken.

3.5.5 Accuracy of the graph prepared

In the previous CBR proficiency program all participants results were re-graphed. In

this program, only a selected group have been re-graphed. Consequently, any

inconsistencies will not be classed as outliers.

Graphing is discussed in this program due to its importance in deriving an accurate

result and being able to check the CBR result obtained. The CBR test method does

not emphasis this aspect.

Graphing of results has been an issue for the last eight CBR proficiency programs (8

years!). Overall graphing has improved vastly over this time but there is still

considerable room for improvement.

In nearly every case you can take the raw data from a AS 1289 test method and

anyone given the data would calculate the same result. With CBR the raw data can

be given to 12 or more laboratories and possibly get 12 different answers!

From a testing perspective this is unacceptable but meets the test method

requirements. This is not the fault of laboratories. However, laboratories have within

their abilities to improve on this.

Regardless of what graph is submitted to the client a detailed graph for use by the

laboratory is important as it is the primary method of checking that a reasonable result

has been obtained.

The test method is also not very descriptive regarding the quality of the graph

prepared. In previous proficiency programs, considerable feedback was given. An

example graph is given in Appendix C of the level of detail considered useful.

From Table 3.5.5A it shows a variation of results due to the accuracy of graphing. The

difference in CBR results shown are considerable. In nearly all cases the change is

towards the CBR median value of 52% for sample A.

If the z-scores for all participants were recalculated with these seven amended

CBR results the NIQR decreases by 0.66 and the CV decreases by 1.2%.

Participants shown in Table 3.5.5A need to review their results.



Participant Recalculated Review Participant Recalculated Review

Participant Code

Zero Correction

(mm)

Zero Correction

(mm) Difference

Unrounded CBR (%)

Unrounded CBR (%)

Difference

B5 1.4 1.2 -0.2 116.1 98.6 -17.5

G9 1.0 3.8 2.8 23.5 49.6 26.1

V6 2.0 1.7 -0.3 73.1 63.3 -9.8

B9 3.5 2.5 -1.0 65.1 54.8 -10.3

F7 2.7 2.1 -0.6 55.2 48.7 -6.5

C6 0.0 2.0 2.0 21.3 35.9 14.6

P7 1.5 0.9 -0.6 47.9 59.6 11.7

Table 3.5.5A Selected participants – Sample A re-graphed CBR data results

3.5.6 Zero-point correction

Overall, most participants calculated a zero-point correction and applied it. Seating load and zero correction combined generally result in small changes.

However sometimes small changes can have a significant effect and particularly when

a BR value is to be rounded either up or down to the nearest 10%. A variation of ± 20

% CBR is not unrealistic.

Not applying the zero-point correction does have a significant impact as shown in table

3.5.5A.

It highlights the need for the middle group of participants to review their results as

much as those at the upper and lower edges. Overall many participants should revisit

the graphing technique employed.

3.5.7 Rounding of CBR

The reason for rounding is not entirely clear in the Australian Standard. It perhaps

acknowledges that CBR values are quite variable and rounding makes the results

easier to use and compare when grouped together i.e. takes out some of the

fluctuation.

Laboratories were asked for the unrounded Bearing Ratio rather than rounded CBR

results. Part of the design consideration of this program was to try and isolate as well

as minimise sources of variation. The process of ‘rounding’ was identified as adding

to the variation of determining CBR. The statistics associated and test variation with

the CBR results will often increase slightly if rounded results are used. At other times

it may slightly decrease the variation shown.



3.6 Indirect Influences

The following aspects of testing methodology are difficult to relate to the final CBR test

result. They can be measured individually but the influence it has on the CBR result

is more difficult due to the ‘unknown interactions’ they have on each other.

It is clear however that more accurate measurement of these aspects of the test in

conjunction with better definition within the test method should assist with improving

the overall accuracy of the test.

3.6.1 Pre-compaction curing

There were a range of curing times used by participants. The majority used 48 hours and above. The curing times specified by the test method are minimums. More curing, if done correctly, is better than less.

The test method now requires laboratories to select the appropriate curing time based

on material, Liquid Limit and departure from OMC.

There were a wide range of ‘liquid limit’ values used and hence a wide range of curing

times. The 2017 amendment to the test method allows for the ‘liquid limit’ to be

estimated based on experience. Most participants based the curing on their ‘estimate’

of ‘liquid limit’. This would appear to be a weakness in the test method.

An estimate of the MC of the material as received and whether within 2% of the OMC

was not requested as part of this program.

Participants (D6, Y8, L2, J4, D7, W2, R4, G9, G5, W6) used curing times of 2 hours.

These curing times are at odds with the rest of the participants and should be

reviewed.

The process to be used when curing material does not appear to be covered in the

test method apart from clause 5(f). Thus, there is a strong probability that many

laboratories use quite different approaches, some being more effective than others.

Samples need to be in sealed containers and the material broken up and mixed

regularly during curing. Water should be added as a mist to the largest surface area

possible. Condensation on the container side and lid needs to be monitored. Regular

mixing should avoid material on the bottom being wetter than the rest of the material.

Section 6c of the test method requires the material to be within ±0.5% of the specified

moisture. For this program OMC was 8.5%. The allowed range then was 8 to 9%.

The following participants (W2, G9, Z6) indicated MCs outside this range and should

investigate.



3.6.2 CBR compaction

The proficiency program required participants to perform the CBR compaction using the OMC and MDD values provided and 100 % standard compaction. Test methods relating to compaction are very specific about the energy input into the process. This is largely governed by the spread of hammer blows and the number of blows used. The revised CBR method now stipulates the pattern to be used when compacting the CBR mould. The test method however does not specifically require the number of blows delivered to be recorded. As it is an important part of the test it should be recorded. It is expected that by compacting a calculated amount of material to a set height that the desired density will be achieved. The blows will vary depending on the material type and moisture. Depending on how this is done a variation in the number of blows per layer is the typical outcome. However, between layers these should remain reasonably close. For determination of OMC/MDD using standard compaction 25 blows per layer is used. To achieve the same energy input around 53 blows is required for the larger CBR mould. More or less blows than 53 may be needed for a variety of reasons.

• Inaccuracy of the OMC and MDD initially

• Blows not delivered in a regular pattern

• Nature of the material may cause it to move around the mould excessively

• Material added is higher or lower than the prescribed layer depth The blows delivered provides an insight into whether any of the above issues may have had an effect. Relying on the dry density calculated is useful but it is a calculated value and dependant largely on how representative and accurate was the moisture determination. How much variation is reasonable. This is at present unknown but for this program a variation of 40 to 60 has been used with a variation between layers of 5 blows. This criterion is meet by the majority of participants. The following participants shown in table 3.6.2A do not meet this criterion and should review their results. Those shown in bold have more than 5 blows between layers.



Sample A Sample B

< 40 Blows per layer > 60 blows per layer < 40 Blows per layer > 60 blows per layer

Y5, C5, P4, S2, Q9, M6, Y3, Q8, L6, G5, W6, Q2, B9, F7, P7,

R3, U2

-

V2, Y5, C5, P4, S2, Q9, M6, Y3, U2, Q8, L6, G5, W6, Q2, B9,

F7, P7

-

Table 3.6.2A Participants with high or low number of compaction blows.

The bulk of participants, outside the limits set, used 40 or less blows per layer. It may not affect the dry density obtained but there is concern that it may have an effect on the CBR obtained. For low compaction it may have an effect on:

• segregation of particles

• uneven compaction, For high compaction, effects such as:

• orienting the soil particles,

• segregation of particles

• causing fissures,

• breaking up of particles

• uneven compaction, all of which could influence the CBR without affecting the dry density value achieved. CBR results may be higher or lower depending on the influence. As far as is known these issues have not been investigated in recent times. There is also the possibility that these results may not belong to the general population of test results for this program. 3.6.3 OMC & MDD

Different determinations of OMC & MDD by different laboratories will give rise to a

spread of results (Variation). To limit the effect of this variation on the CBR testing in

this proficiency program the OMC & MDD have been predetermined. This information

was supplied to participants (See instructions Appendix A) so that all participants used

the same OMC & MDD values.



3.6.4 LDR and LMR

❖ Calculation of LDR & LMR

Participants were requested to submit:

• The sample moisture immediately prior to compaction (w1) in accordance with

clause 6(c) of the standard.

• Moisture content variation (wv)

• The Laboratory Moisture Ratio (LMR)

• The Laboratory Density Ratio (LDR) and

• Dry Density (before soaking)

These intermediate results are noted in the test method as needing to be reported or

required to determine compliance with the test method.

The reported LDR and LMR values were re-calculated using the reported moisture

from clause 6(c) and density (before soaking). It is suspected that several participants

had incorrectly reported the moisture of the sample as being that of ‘as received’.

There were several participants that had difficulty in calculating the intermediate

results detailed above. There were also many participants that did not report LMR &

LDR to the correct number of decimals or had rounded incorrectly.

The participants listed in Table 3.6.4A showed inconsistencies in the values submitted

throwing doubt on compliance with the test method and should be investigated.

Information submitted Investigate

Sample A B

Moisture (Clause 6c) W2, G9, Z6, F7 W2, G9, Z6, F7

Variation in moisture content (not) reported - -

LMR does not match reported moisture R8, W2, R4, G9, Z6, F7, E3 R4, G9, Z6, Q2, F7

LDR does not match reported dry density L2, P4, Z6, D5 B4, R4, P4, D5

Table 3.6.4A: Participants with inconsistencies in calculating LMR and LDR



❖ Achievement of OMC & MDD

Participants were requested to compact the sample to 100 % standard compaction.

Overall most participants achieved the desired range for OMC and MDD which was a

very good outcome. Achieving the LMR and LDR is a requirement of the test method

and must be met for the results to be valid and hence reportable.

OMC

± 0.5%

Moisture

Range

%

LMR Range

%

Investigate

Sample A

Investigate

Sample B

W2, G9, Z6 D6, L2, G9, Z6

8.0 94.2

8.5

9.0 105.8

MDD

t/m3

Density

Range

t/m3

LDR Range

± 1%

Investigate

Sample A

Investigate

Sample B

P4, G9 P4

2.064 99.0

2.085

2.106 101.0

Table 3.6.4B: Participants that are outside the limits set for LMR and LDR OR W1.

Participants with results outside these limits as detailed in Table 3.6.4B. It suspected

that in many cases LMR and LDR would have been achieved had the participant

calculated them correctly. Most had the moisture before compaction (W1) value less

than 8.0%.

Results outside the permitted LMR and LDR ranges could have been rejected from

the proficiency program but were retained in this instance.



3.7 Test method

Often as part of a proficiency testing programs there is a need to discuss aspects of

the test that can be identified as contributing to the overall variation in the test results

produced. It does not mean the test method needs to change only that it is important

for laboratories to know which aspects of the test, if not performed well, could add to

the variability of the outcome.

The need to change the test method only arises if the accuracy and variability

in the test results is not within the expected range.

Aspects of the test that may contribute to improving the accuracy and possibly

reducing the variability are:

• Need for more sample, so test can be repeated if required

• Standardised approach to curing – e.g. spray or mist, sealed container etc.

• Better definition of graphing, curve fitting and rogue points

• Background on using graph or other to validate CBR result.

• Use of more penetration points

• Guidance on suspect data values

• Better definition as to what is meant by penetration rate

• Actual measured penetration rate per 1 mm to be recorded for each test

• Recording the number of blows, i.e. energy input and an expected range given

• Limits on number of blows per layer and between layers

• Better definition of zero correction and ‘straight line’ fitting

• Test performed in duplicate with limit on repeatability

• Need for more background guidance to reduce variability of opinion on how to

perform test

• Limit FSD of load cell/ring to CBR value obtained. I.e. not use a 100kN load

cell for a CBR of 15.

• Requirement to standardise the test using a known material that gives a CBR

of 100%

• Define acceptable repeatability and reproducibility for the test.

• Use the average of two samples to report the average value. Results must be

within repeatability value.

• Curing time issues resolved



B4 43.0 -0.78 B8 52.5 0.04

R8 44.2 -0.67 U9 60.6 0.74

V2 51.8 -0.02 G5 52.0 0.00

B5 116.1 5.54 # W6 60.6 0.74

D6 44.4 -0.66 D8 40.9 -0.96

Y8 47.0 -0.43 Q2 52.8 0.07

L2 74.8 1.97 B9 65.1 1.13

J4 52.5 0.04 F7 55.2 0.28

D7 55.1 0.27 X6 55.4 0.29

Y5 66.6 1.26 D5 60.0 0.69

W2 43.0 -0.78 C6 21.3 -2.65

C5 45.1 -0.60 M2 45.0 -0.61

R4 24.7 -2.36 P7 47.9 -0.35

G7 E3 54.0 0.17

R3 63.6 1.00 J3 52.2 0.02

P4 33.7 -1.58

G9 23.5 -2.46

V6 73.1 1.82

S2 61.2 0.80

Q9 53.3 0.11

M6 66.0 1.21

Y3 48.0 -0.35

W3

Z6 50.1 -0.16

U2 41.8 -0.88

Q8 40.5 -0.99

L6 44.9 -0.61

D2 50.9 -0.10

Number of results 41

Median 52.0

Median MU 2.26

First Quartile 44.4

Third Quartile 60.0

IQR 15.60

Normalised IQR 11.56

CV (%) 22.2

Minimum 21.3 (21.3)

Maximum 74.8 (116.1)

Range 53.5 (94.8)

Note: A # indicates an outlier where the z-score obtained is either greater then

3 or less than -3. Codes 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.

4.1 CBR - Part A: Z - Scores

CodeTest

Result %

Z Score CodeTest

Result %

Z Score

Statistic Value



ReviewWeak

Consensus

Weak

ConsensusReview

Z-score

Strong Consensus

4.1 CBR - Part A: Z - Score Graph

B5

L2

V6

Y5

M6

B9

R3

S2

U9

W6

D5

X6

F7

D7

E3

Q9

Q2

J4

B8

J3

G5

V2

D2

Z6

Y3

P7

Y8

C5

M2

L6

D6

R8

B4

W2

U2

D8

Q8

P4

R4

G9

C6

-3 -2 -1 0 1 2 3



B4 42.0 -1.12 B8 59.6 0.45

R8 47.4 -0.64 U9 58.9 0.38

V2 48.7 -0.53 G5 0.53

B5 107.0 4.67 # W6 66.3 1.04

D6 66.2 1.03 D8 41.0 -1.21

Y8 53.8 -0.07 Q2 51.4 -0.28

L2 57.6 0.27 B9 66.1 1.02

J4 57.6 0.27 F7 58.2 0.32

D7 53.5 -0.10 X6 54.3 -0.03

Y5 56.6 0.18 D5 45.0 -0.85

W2 C6 26.7 -2.48

C5 54.9 0.03 M2 60.0 0.48

R4 43.0 -1.03 P7 62.0 0.66

G7 E3 51.3 -0.29

R3 65.0 0.93 J3 48.8 -0.52

P4 32.8 -1.94

G9 15.8 -3.45 #

V6 68.7 1.26

S2 59.6 0.45

Q9 57.9 0.29

M6 59.8 0.46

Y3 50.2 -0.39

W3

Z6 39.9 -1.31

U2 39.7 -1.33

Q8 39.2 -1.37

L6 35.9 -1.67

D2 56.9 0.20

Number of results 40

Median 54.6

Median MU 2.22

First Quartile 44.5

Third Quartile 59.7

IQR 15.15

Normalised IQR 11.23

CV (%) 20.6

Minimum 26.7 (15.8)

Maximum 68.7 (107.0)

Range 42.0 (91.2)

Note: A # indicates an outlier where the z-score obtained is either greater then

3 or less than -3. Codes 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.

4.2 CBR - Part B: Z - Scores

CodeTest

Result %

Z Score CodeTest

Result %

Z Score

Statistic Value



ReviewWeak

Consensus

Weak

ConsensusReview

Z-score

Strong Consensus

4.2 CBR - Part B: Z - Score Graph

B5

V6

W6

D6

B9

R3

P7

G5

M2

M6

S2

B8

U9

F7

Q9

L2

J4

D2

Y5

C5

X6

Y8

D7

Q2

E3

Y3

J3

V2

R8

D5

R4

B4

D8

Z6

U2

Q8

L6

P4

C6

G9

-3 -2 -1 0 1 2 3



5. Program information 5.1 Z score Summary The proficiency program was conducted in September/October 2017. A ‘Z-score Summary’ summary was issued on the 30 November 2017. A copy was e-mailed to all participants who submitted results. The summary is intended as an early indicator of participant performance. This program report supersedes the z - score summary. Further information can be found in section 5.9 ‘Statistics’. The z-scores generally do not vary significantly between the “summary” and the “Final Report”. 5.2. Program Design 5.2.1 Design

This program is one of a series of CBR programs conducted by LabSmart Services over the last ten years. Proficiency testing programs have shown that the CBR test produces a wide variation in results. Part of the design of each program involves asking for the right information. The correct analysis of the data collected then allows feedback to be offered to enable participants to improve in the performance of this test. 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. 5.2.2 Selection of material for the program

The test in this proficiency program is operator skill/experience dependant. Different materials are selected for each program to mirror the range of materials encountered in practice and hence the results obtained. The higher the CBR value the greater the variation encountered. This program provides a sample that gives results in the range that would be commonly tested by laboratories. It is expected that the level of experience/skill need to perform these tests will present a reasonable assessment of the overall competency of the tester and industry performance. 5.2.3 OMC & MDD

The determination of OMC and MDD is usually an initial stage undertaken prior to performing a CBR test. The determination of these two parameters can show a significant variation. In turn having an impact on the variation obtained for CBR results. The intention of the program is to minimise the influence on the CBR results that could arise from laboratories determining these values in-house and reduce the likelihood of different OMC and MDD values being applied.



To assist in reducing this variation, participants were requested to use 100% standard compaction and use:

• OMC = 8.5%

• MDD = 2.085 t/m3. These values were determined prior to the program. The same type of material was used in a later compaction program (76) held during 2017 that yielded medians of 8.6 and 2.093. it is important to noted that this was a different program with different participants and therefore a difference in results is not unexpected. Although this has been the approach to try and minimise variation other aspect may still contribute to the variation observed. OMC/MDD values may vary from person to person but this may not be so important if the same person determines OMC/MDD and CBR. That is a low compaction on the OMC/MDD should give the same compaction on the CBR. Overall it is still considered that a set OMC/MDD will contribute the least variation. 5.2.4 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. 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 next most useful tool a laboratory has in better understanding the performance of a test. 5.2.5 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. 5.2.6 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 and test method accuracy 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 example, rounding to 10 % means that any number between 45 and 54 will become 50%. If the largest value is 45 in a set of results it is pushed out to 50 through rounding. Rounded results may better reflect the repeatability and reproducibility of the test according to the rounding in the test method but are not as useful when considering laboratory performance. For this program, it was decided that the benefits of using additional decimal places would complement the aim of the proficiency program. Participants results were analysed as received regardless of whether there were more or less significant figures than the number requested by the program. 5.2.7 Additional information requested

This program requested additional information as detailed in Section 6 not usually reported. The additional information is however consistent with the performance of the test and the records the test method requires laboratories to maintain or is consistent with ‘good laboratory’ practice. The additional information is used to interpret participant’s performance and assist with providing technical comment including feedback on outliers and possible participant improvement. 5.2.8 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.

5.3. Sample preparation Sufficient material of a homogeneous appearance was obtained for the proficiency program. The lot was partially dried then mixed to ensure, as far as possible, a homogeneous material throughout. The material was sampled and placed into numbered plastic bags. Ten samples were drawn at regular intervals from the lot for homogeneity testing. Each participant received a randomly drawn sample from the remaining samples. A unique program code was assigned to each sample.



5.4. Packaging and instructions Each plastic bag was sealed with a rubber band and placed into a sturdy box. Each participant received one box with a sealed sample labelled ‘2017 (74) CBR Sample’. The sample weighed approximately 15.5 kg. Instructions and a ‘Results Log’ sheet were enclosed (See Appendix A & B). Participants were instructed to test according to the nominated test method and report to the accuracy indicated on the ‘Results Log’.

5.5. Quarantine No additional preparation was required for this program.

5.6. Sample despatch Samples were dispatched to participants between 19 September 2017 via courier. Dispatched samples were tracked from ‘despatch to delivery’ for each participant.

5.7. Homogeneity testing Homogeneity samples were selected, evenly spaced, from the prepared participant samples. Samples for homogeneity testing were packed in the same way as those for all participants. The homogeneity samples were tested by an independent NATA accredited laboratory. To approximate the same conditions the same instructions were given to the laboratory performing the homogeneity testing. Ten samples were tested for homogeneity. The overall variability associated with the homogeneity samples was considered satisfactory. The average of the homogeneity samples also lies within 1 s.d of the program median value. This provides confidence that any outliers identified in the program represent statistically valid outliers. A statistical analysis of the homogeneity testing results is provided in table 5.7A.

5.8. Participation Forty-three participants from around Australia entered the program. Around Forty-one participants returned results. Participants were requested to return results by 17 October 2017.

5.9. 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. Therefore, 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. Assessment of participant’s data is undertaken to ensure data is statistically comparable. Checks are undertaken to ensure the data calculated matches that reported by the participant and that the appropriate corrections etc. have been applied if required. The level of checking required varies from program to program. If inconsistencies are identified the data may be removed or amended with the discrepancy highlighted.

Code

Bearing Ratio CBR

(Rounded) % 5.0 mm

%

H1 59.9 60

H2 57.3 60

H3 54.2 50

H4 42.9 45

H5 36.5 35

H6 59.5 60

H7 43.9 45

H8 43.1 45

H9 46.2 45

H10 51.8 50

Mean 49.5 49.5

Standard Deviation 8.1 8.3

Range 23.4 25.0

Coefficient of Variation (%) 16.4 16.8

Table 5.7A Homogeneity results

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 are an approximate of the standard deviation. For each test a z-score graph is shown. Use the graph to visually check statistically how you compare to other participants. The following bar (Figure 5.9A) is shown at the bottom of each graph. This helps to quickly visualize where each participant’s results falls.

Review Weak

Consensus Strong Consensus

Weak Consensus

Review

Figure 5.9A 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. Participant assessment is not based purely on statistical analysis. Compliance to proficiency program requirements including the correct calculation of results and adherence to program 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. 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. 5.9.1 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 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 5.1 of the report. 5.9.2 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.



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. 5.9.3 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. 5.9.4 Metrological traceability

The assigned median value used in this proficiency testing program is derived from participant performance and is not metrologically traceable. 5.10 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 that erroneous results may 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.



Code B4 R8 V2 B5 D6 Y8 L2

Moisture-Before compaction - W1 (%) 8.4 8.5 8.4 8.46 8.2 8.4 8.0

Moisture Content Variation - Wv (%) 0.1 0.0 0.1 0.04 -0.3 -0.1 -0.5

Compaction (Manual or Auto) M M M M M M M

Compaction Method - Standard (Y/N) Y Y Y Y Y Y Y

No. blows per layer 53/53/53 53/53/53 43/43/41 45/45/45 53/53/53 53/53/53 53/53/53

Dry Density g/cm3

2.082 2.090 2.087 2.086 2.092 2.089 2.044

Density Ratio (LDR) % 99.9 100.2 100.1 100.0 100.3 100.2 100.4

Moisture Ratio (LMR) % 98.8 98.8 98.8 99.5 96.5 98.8 94.1

BR @ 2.5 mm (%) 35.9 44.2 37.7 106.0 32.6 35.6 55.3

BR @ 5.0 mm (%) 43.0 43.4 51.8 116.1 44.4 47.0 74.8

CBR (%) 43.0 44.2 51.8 116.1 44.4 47.0 74.8

Correction (mm) 3.1 0.2 0.8 14 2.0 1.5 2.4

Swell (%) -0.2 -0.4 0 -0.2 0.0 0.0 0.0

Moisture ww 8.3 8.5 8.9 8.46 8.2 8.4 8.1

Moisture w30 8.7 8.6 9.1 8.85 8.5 8.8 8.4

Moisture wr 7.9 8.0 N/A 8.65 8.0 8.0 7.6

Date last calibrated 7/10/15 4/08/17 13/01/16 7/10/16 27/06/17 27/06/17 27/06/17

Calibrated range (kN) 0-50kN 0-50kN 500Nx0.001 0-50kN 50kN 50kN 50kN

Load cell (C) or ring (R) C C C R C C C

Calibration Class (AA, A, B, C etc) A A A A C C C

Hand driven (H) or motorised (M) M M M M M M M

Rate of penetration (mm/min)

Average 1.2 1.1 0.973 1mm/min 0.999 0.999 0.999

Lowest 1.1 1.0 0.858 1mm/min 0.983 0.983 0.983

Highest 1.2 1.2 1.007 1mm/min 1.02 1.02 1.02

Condition of material Moist Moist Dry Dry Good Good Good

Seating load applied (N) 0.045kN 45N 150N 0.4 0.01 0.01 0.01

Seating load set to zero (Y/N) Y Y Y Y Y Y Y

LL determined by clause(5d)1, 2 or 3 1 1 3 NR 3 3 3

LL value used 29.0 30 ≤35 NR <12 <12 <12

Period Cured (hours) 24 24 72 6 2 2 2

Graph computer or hand (C/H) C C C NR C/H C/H C/H

Loads in ( N or kN ) kN kN N kN kN kN kN

0 0 0 0 NR 0.00 0.00 0.01

0.5 0.033 1.028 375 0.3 0.03 0.08 0.03

1 0.108 2.125 875 0.9 0.12 0.23 0.08

1.5 0.253 3.405 1570 1.5 0.31 0.51 0.25

2 0.462 4.580 2430 3 0.69 1.13 0.54

2.5 0.760 5.570 3390 4.9 1.31 1.90 1.18

3 1.217 6.355 4360 7.1 1.94 2.83 2.09

3.5 1.675 7.023 5370 9.2 2.69 4.01 3.30

4 2.276 7.541 6420 11.5 3.66 4.81 4.69

4.5 2.922 8.077 7540 13.1 4.37 5.57 6.15

5 3.741 8.452 8610 15.1 5.48 6.77 7.63

6 5.278 9.295 10700 16.90 7.09 8.53 10.71

7.5 7.580 10.361 13730 24.1 9.84 11.00 15.18

8 8.300 10.589 14650 25.6 10.77 11.81 16.65

10 11.580 NR 18600 31.6 14.30 15.29 22.0710.5 1mm/min12.5 14.819 NR 23280 38.7 19.42 19.94 29.01


Number 1 2 3 4 5 6 7

6 Particpants Test Results - Sample A

Table 1 of 7Note: Blank or NR = No result returned, Green are calculated/corrected results by PT coordinator.



Code J4 D7 Y5 W2 C5 R4 G7

Moisture-Before compaction - W1 (%) 8.3 NR 8.3 5.6 8.3 8.0

Moisture Content Variation - Wv (%) -0.2 NR 0.2 2.9 0.2 0.5

Compaction (Manual or Auto) M NR M M M M

Compaction Method - Standard (Y/N) Y NR Y5 Y Y Y

No. blows per layer 53/53/53 NR 25/25/25 53/54/55 40/39/39 53/53/53

Dry Density g/cm3

2.095 NR 2.089 2.098 2.100 2.094

Density Ratio (LDR) % 100.5 NR 100.2 100.6 100.7 100.5

Moisture Ratio (LMR) % 97.7 NR 97.7 98.8 97.6 99.5

BR @ 2.5 mm (%) 39.4 40.9 55.3 32.4 34.6 45.2

BR @ 5.0 mm (%) 52.5 55.1 66.6 43.0 45.1 58.8

CBR (%) 52.5 55.1 66.6 43.0 45.1 58.8

Correction (mm) 1.90 2.28 0.6 1.6 1.2 3

Swell (%) 0.0 NR -0.1 -0.3 -0.3 0.0

Moisture ww 8.6 NR 9.1 8.4 8.9 8.5

Moisture w30 9.1 NR 8.9 8.5 8.9 9.1

Moisture wr 7.8 NR NR 8.4 8.3 8.1

Date last calibrated 27/06/17 27/06/17 12/07/17 22/06/16 30/05/17 14/06/16

Calibrated range (kN) 50kN 50kN 0-50kN 0-50kN 0-50kN 0-50kN

Load cell (C) or ring (R) C C C C C C

Calibration Class (AA, A, B, C etc) C C A A A A

Hand driven (H) or motorised (M) M M M H H M


Average 0.999 0.999 1.13 1mm/min 1mm/min NR

Lowest 0.983 0.983 1.13 1mm/min 1mm/min NR

Highest 1.02 1.02 1.13 1mm/min 1mm/min NR

Condition of material Good Good Satisfactory Moist Damp OK

Seating load applied (N) 0.01 0.01 Y 250 0.050kN <50

Seating load set to zero (Y/N) Y Y Y Y Y Y

LL determined by clause(5d)1, 2 or 3 3 3 3 3 3 3

LL value used <12 <12 30 <35 <35 ≤35

Period Cured (hours) 2 2 72 8 24 12

Graph computer or hand (C/H) C/H H C C C C

Loads in ( N or kN ) kN kN N N kN N

0 0.01 0.01 0 0 0.000 50seat

0.5 0.07 0.07 610 218 0.302 87

1 0.20 0.21 1600 520 0.708 181

1.5 0.43 0.43 2890 926 1.222 331

2 0.89 0.85 4170 1428 1.880 569

2.5 1.54 1.35 5610 2068 2.550 934

3 2.37 2.09 7050 2718 3.400 1448

3.5 3.35 2.89 8300 3386 4.186 2117

4 4.33 3.86 9610 4144 5.026 2934

4.5 5.41 4.90 10700 4988 5.586 3867

5 6.51 5.97 11930 5814 6.830 4897

6 8.59 8.19 14000 7398 8.613 7054

7.5 11.58 11.43 17190 10068 11.155 10501

8 12.65 12.68 18050 10920 12.095 11639

10 16.48 16.50 21720 NR 15.475 1611610.5 NR12.5 21.66 21.77 26230 NR 19.450 NR


Number 8 9 10 11 12 13 14

Note: Blank or NR = No result returned, Green are calculated/corrected results by PT coordinator.

6 Particpants Test Results - Sample A 6 Particpants Test Results - Sample A

Table 2 of 7



Code R3 P4 G9 V6 S2 Q9 M6


Moisture Content Variation - Wv (%) -0.2 0.0 2.8 0.2 0.0 0.3 0.5

Compaction (Manual or Auto) M A M M M M M



Dry Density g/cm3

2.090 1.927 2.107 2.087 2.085 2.092 2.092

Density Ratio (LDR) % 100.2 100.3 101.1 100.1 100 100.3 100.3

Moisture Ratio (LMR) % 97.6 99.6 101.5 97.6 100 96.5 94.1

BR @ 2.5 mm (%) 48.8 28.7 1.260 71.6 50.2 39.2 46.1

BR @ 5.0 mm (%) 63.6 33.7 4.650 73.1 61.2 53.3 66.0

CBR (%) 63.6 33.7 23.5 73.1 61.2 53.3 66.0

Correction (mm) 0.92 0.4 1 2.0 1.5 1.8 1.0

Swell (%) -0.5 0.0 0 0.0 -0.1 0.0 0.0

Moisture ww 8.8 10.6 101.3 9.4 9.0 9.1 8.3

Moisture w30 8.4 10.1 9.3 8.4 8.7 9.0 9.4

Moisture wr 7.8 9.7 8.7 9.4 8.2 8.8 8.4


Calibrated range (kN) 0-50kN 0-100kN 0-50kN 0-40kN 1-50kN 50kN 0.045-50kN

Load cell (C) or ring (R) C C R C C C C

Calibration Class (AA, A, B, C etc) A A AA A A NR A

Hand driven (H) or motorised (M) M M M M H M M


Average NR 0.98 Average 1mm/min 1mm/min 0.94 1mm/min

Lowest 1.00mm 0.93 NR NR NR 0.83 NR

Highest 0.8mm/min 1.01 NR NR NR 1.14 NR

Condition of material Dry Moist Sealed Good Dry Dry Good

Seating load applied (N) 250N 50N dial gauge 250 50N 50N 0.045


LL determined by clause(5d)1, 2 or 3 3 1 3 3 3 1 3

LL value used ≤35 19 ? ? Medium NP 25


Graph computer or hand (C/H) C C C C C C NR

Loads in ( N or kN ) N N kN N N N kN

0 NR 2 0 0 0 0 0.000

0.5 487 230 0.029 349 227 82 0.175

1 1201 885 0.084 801 695 217 0.430

1.5 2115 1655 0.176 1365 1397 518 1.040

2 2901 2455 0.327 2069 2273 1028 2.090

2.5 4250 3199 0.546 2902 3269 1694 3.300

3 5432 3886 0.843 3838 4265 2549 4.700

3.5 6603 4526 1.260 4821 5470 3493 6.130

4 7808 5154 1.729 5863 6726 4551 7.550

4.5 9126 5713 2.302 7011 7850 5615 8.900

5 10351 6231 3.002 8166 9111 6779 10.350

6 12995 7146 4.653 10671 11126 8986 13.200

7.5 16400 8351 7.273 14480 14011 11902 16.500

8 17321 8652 8.229 15730 14845 13135 17.600

10 21961 9773 12.204 20710 17804 16908 21.70010.512.5 27099 10730 17.167 26850 21435 21756 25.900


Number 15 16 17 18 19 20 21



Table 3 of 7



Code Y3 W3 Z6 U2 Q8 L6 D2

Moisture-Before compaction - W1 (%) 8.8 6.1 8.6 8.2 8.3 8.7

Moisture Content Variation - Wv (%) -0.3 -2.4 0.1 0.3 -0.2 -0.2

Compaction (Manual or Auto) M M A M M M

Compaction Method - Standard (Y/N) Y Y Y Y Y Y

No. blows per layer 35/20/20 53/53/53 23/25/30 25/25/25 39/41/38 53/53/53

Dry Density g/cm3

2.078 2.087 2.083 2.075 2.086 2.096

Density Ratio (LDR) % 99.7 100.5 99.9 99.5 100.0 100.5

Moisture Ratio (LMR) % 103.5 98.8 101.2 96.1 97.6 102.4

BR @ 2.5 mm (%) 38.6 37.9 33.4 34.2 37.6 30.4

BR @ 5.0 mm (%) 48.0 50.1 41.8 40.5 44.9 50.9

CBR (%) 48.0 50.1 41.8 40.5 44.9 50.9

Correction (mm) 0.6 3.3 0.4 0 1.3 2.2

Swell (%) -0.1 0.9 0.0 -0.2 0.1 0.4

Moisture ww 9.8 8.3 9.1 9.4 9.3 8.1

Moisture w30 8.7 8.6 9.9 9.7 9.3 8.5

Moisture wr 8.7 8.3 8.4 9.0 9.3 7.9


Calibrated range (kN) 0.001-50kN 4-1500kN 50kN 50kN 50kN 0-50kN

Load cell (C) or ring (R) C C R C C C

Calibration Class (AA, A, B, C etc) A A A A A/B A

Hand driven (H) or motorised (M) M H M M M M


Average 0.978 1mm/min 1mm/14sec 1mm/sec 1mm/min 1.000

Lowest 0.92 1mm/min 1mm/1sec NR 1mm/min 0.998

Highest 1.02 1mm/min 1m/30sec NR 1mm/min 1.001

Condition of material Good Moist Moist Moist OK Dry

Seating load applied (N) 50N -0.015 59.5 250N 45N 0

Seating load set to zero (Y/N) Y Y N Y Y Y

LL determined by clause(5d)1, 2 or 3 1 NR 1 3 3 ≤35

LL value used <17 NR 21.4 ? <35 ≤35


Graph computer or hand (C/H) C NR C C H C

Loads in ( N or kN ) kN kN N kN kN N

0 0.00 0 59.5 0 0.02 0

0.5 0.329 0.016 586 0.654 0.10 129

1 0.984 0.049 1362 1.556 0.36 296

1.5 1.916 0.127 2191 2.627 0.81 551

2 2.949 0.274 3001 3.611 1.42 922

2.5 3.987 0.500 3836 4.519 2.13 1403

3 4.954 0.884 4626 5.353 2.91 1995

3.5 5.896 1.402 5370 6.093 3.73 2864

4 6.790 2.073 6060 6.781 4.60 3809

4.5 7.707 2.874 6718 7.397 5.49 4822

5 8.549 3.816 7403 8.010 6.37 5836

6 10.279 5.991 8679 9.055 8.29 7953

7.5 12.679 8.930 11075 10.442 11.32 11289

8 13.367 9.928 11738 10.822 12.40 12284

10 16.246 14.130 13919 12.212 16.43 1644310.512.5 20.112 19.054 16146 13.688 21.28 21186


Number 22 23 24 25 26 27 28



Table 4 of 7




Code B8 U9 G5 W6 D8 Q2 B9


Moisture Content Variation - Wv (%) 0.0 0.3 0.3 0.1 0.0 0.2 -0.1

Compaction (Manual or Auto) A M M M M M M



Dry Density g/cm3

2.086 2.091 2.083 2.084 2.083 2.085 2.085



BR @ 2.5 mm (%) 38.7 47.8 40.9 46.2 31.6 43.1 56.7

BR @ 5.0 mm (%) 52.5 60.6 52.0 60.6 40.9 52.8 65.1

CBR (%) 52.5 60.6 52.0 60.6 40.9 52.8 65.1

Correction (mm) 1.4 4-4.5mm 0.8 1.2 2.7 0.4 3.5

Swell (%) -0.2 0.0 -0.1 -0.1 -0.7 -0.1 -0.2

Moisture ww 9.1 8.4 9.2 9.1 8.6 9.5 8.6

Moisture w30 8.9 8.2 9.1 8.5 9.1 9.0 9.7

Moisture wr 8.9 8.0 NR NR NR 8.4 8.3


Calibrated range (kN) 0-100kN 0-50kN 0-50kN 0-50kN 0-50kN 2-50kN 2-50kN

Load cell (C) or ring (R) C C C C C C C

Calibration Class (AA, A, B, C etc) A A/B/C A A A A A



Average 1.01 0.98 NR NR 0.96 1mm/min 0.93

Lowest 0.94 0.99 1.0 1.0 0.88 NR 0.88

Highest 1.07 1.02 1.0 1.0 1.05 NR 1.00

Condition of material Moist Good Moist Moist Moist Moist Drier

Seating load applied (N) 0.15kN 0.045kN 50N 50N 45N 0.05N 30N

Seating load set to zero (Y/N) Y N Y Y Y Y Y


LL value used <35 low ? sand/gravel <35 LowLL <35


Graph computer or hand (C/H) C C C/H C/H C/H C C

Loads in ( N or kN ) kN kN N N N kN kN

0 0.000 0.225 0 0 0 0 0.03

0.5 0.23 0.544 296 171 64 0.6 0.08

1 0.58 1.101 983 540 171 1.52 0.15

1.5 1.07 1.904 1783 1152 349 2.52 0.42

2 1.72 2.926 2705 2005 609 3.70 0.69

2.5 2.46 4.088 3716 3066 961 4.78 1.05

3 3.35 5.278 4811 4232 1415 5.83 1.63

3.5 4.31 4.480 5791 5415 1943 6.82 2.51

4 5.32 6.480 6806 6648 2551 7.77 3.38

4.5 6.41 8.905 7761 7904 3217 8.70 4.41

5 7.52 10.042 8736 9182 3887 9.66 5.38

6 9.60 12.183 10694 11640 5407 11.37 7.52

7.5 12.66 15.228 13116 15098 7811 14.11 10.93

8 13.64 16.226 13956 16174 8545 15.00 11.84

10 17.40 19.704 16922 20314 11603 18.18 16.0110.512.5 22.03 24.061 20191 25382 14277 21.98 21.22


Number 29 30 31 32 33 34 35

Note: Blank or NR = No result returned, Green are calculated/corrected results by PT coordinator. Table 5 of 7




Code F7 X6 D5 C6 M2 P7 E3


Moisture Content Variation - Wv (%) 99.0 0 0.3 0.1 -0.3 0.1 0.0



No. blows per layer 35/35/35 NR NR 53/53/53 NR 25/25/25 53/53/50

Dry Density g/cm3

2.086 2.085 2.09 2.086 2.075 2.085 2.085

Density Ratio (LDR) % 100.1 100 100 100.0 99.5 100 100

Moisture Ratio (LMR) % 103.5 100 96 98.8 103.5 100.5 99.4

BR @ 2.5 mm (%) 47.0 43.2 40 8.7 35 38.0 41.1

BR @ 5.0 mm (%) 55.2 55.4 60 21.3 45 47.9 54.0

CBR (%) 55.2 55.4 60 21.3 45 47.9 54.0

Correction (mm) 2.7 2.0 1.5 0 1.1 1.5 2.2

Swell (%) -0.3 0 0.0 -0.3 -0.1 -0.2 -0.2

Moisture ww 8.4 9.1 8.3 8.9 10.7 9.3 NR

Moisture w30 8.6 8.8 9.0 8.6 9.4 9.4 8.0

Moisture wr 8.2 8.1 NR 8.4 8.6 8.0 7.9


Calibrated range (kN) 2-50kN 50kNx0.001kN 0.2-40kN 0-50kN 50kNx0.01kN 50kN 50Kn


Calibration Class (AA, A, B, C etc) A A A C B/A C A



Average 0.99 1.01 NR NR 0.980 1.00 1.2

Lowest 0.98 0.91 NR NR 1.017 0.96 NR

Highest 1.02 1.06 NR NR 0.943 1.00 NR

Condition of material Damp Good Good OK OK Dry Moist

Seating load applied (N) 0.03 18N 40kN 0.050kN 30N 250N 50kN

Seating load set to zero (Y/N) N Y Y Y Y Y Y

LL determined by clause(5d)1, 2 or 3 3 NR 3 1 16 1 NR

LL value used <35 20 No 18 16 <35 NR

Period Cured (hours) 69 55 24 48 72 48 NR

Graph computer or hand (C/H) C H/C C C C C C

Loads in ( N or kN ) kN N kN kN N N N

0 0.03 0 0.00 0.000 0 0 0

0.5 0.16 202 0.09 0.097 80 417 200

1 0.37 489 0.29 0.227 410 973 450

1.5 0.75 862 0.65 0.452 1010 1735 830

2 1.08 1362 1.22 0.748 1740 2688 1330

2.5 1.61 1997 2.01 1.147 2600 3777 1920

3 2.32 2780 2.99 1.664 3460 4903 2620

3.5 3.01 3765 4.09 2.256 4350 6177 3370

4 3.88 4600 5.18 2.874 5240 7451 4180

4.5 4.90 5702 6.34 3.562 6150 8619 5080

5 5.67 6838 7.53 4.216 6960 9788 6040

6 7.63 8875 9.87 5.581 8560 11623 8140

7.5 10.52 12000 13.21 7.768 10750 15295 11410

8 11.47 13050 14.26 8.517 11450 16381 12450

10 15.2 17252 18.54 11.388 14120 20724 1653010.512.5 20.27 22247 24.39 14.946 17240 25509 21640


Number 36 37 38 39 40 41 42



Table 6 of 7



Code J3

Moisture-Before compaction - W1 (%) 8.5

Moisture Content Variation - Wv (%) 0.0

Compaction (Manual or Auto) M

Compaction Method - Standard (Y/N) Y

No. blows per layer 53/50/52

Dry Density g/cm3

2.097

Density Ratio (LDR) % 100.6

Moisture Ratio (LMR) % 100.0

BR @ 2.5 mm (%) 39.2

BR @ 5.0 mm (%) 52.2

CBR (%) 52.2

Correction (mm) 2.0

Swell (%) -0.2

Moisture ww 9.4

Moisture w30 9.4

Moisture wr 8.4

Date last calibrated 29/05/15

Calibrated range (kN) 0-90

Load cell (C) or ring (R) C

Calibration Class (AA, A, B, C etc) A

Hand driven (H) or motorised (M) M


Average 1mm/min

Lowest 1mm/min

Highest 1mm/min

Condition of material Suitable

Seating load applied (N) 30N

Seating load set to zero (Y/N) Y

LL determined by clause(5d)1, 2 or 3 3

LL value used low

Period Cured (hours) 120

Graph computer or hand (C/H) C

Loads in ( N or kN ) N

0 0

0.5 85

1 237

1.5 520

2 951

2.5 1544

3 2281

3.5 3166

4 4157

4.5 5158

5 6228

6 8330

7.5 11388

8 12349

10 1621410.512.5 20981

Code J3 0 0 0 0 0 0

Number 43 44 45 46 47 48 49



Table 7 of 7





Moisture Content Variation - Wv (%) 0.1 0.0 0.1 0.10 0.5 -0.1 -0.5




Dry Density g/cm3

2.088 2.085 2.090 2.088 2.096 2.091 2.094



BR @ 2.5 mm (%) 34.2 47.4 36.5 85.60 51.5 40.9 43.9

BR @ 5.0 mm (%) 42.0 45.8 48.7 107.0 66.2 53.8 57.6

CBR (%) 42.0 47.4 48.7 107.0 66.2 53.8 57.6

Correction (mm) 3.8 0.2 0.5 13 2.5 2.1 2.0

Swell (%) -0.2 -0.1 0 -0.2 0.0 0.0 0.03

Moisture ww 8.4 8.5 9.0 8.40 8.1 8.4 8.0

Moisture w30 8.6 8.6 8.9 8.96 8.6 8.8 8.7

Moisture wr 7.9 8.0 N/A 8.76 7.8 7.9 7.7


Calibrated range (kN) 0-50kN 0-50kN 500Nx0.001 0-50kN 50kN 50kN 50kN

Load cell (C) or ring (R) C C C R C C C

Calibration Class (AA, A, B, C etc) A A A A C C C



Average 1.2 1.1 0.973 1mm/min 0.999 0.999 0.999

Lowest 1.1 1.0 0.858 1mm/min 0.983 0.983 0.983

Highest 1.2 1.2 1.007 1mm/min 1.02 1.02 1.02

Condition of material Moist Moist Dry Dry Good Good Good

Seating load applied (N) 0.045kN 45N 150N 0.4 0.01 0.01 0.01


LL determined by clause(5d)1, 2 or 3 1 1 3 NR 3 3 3

LL value used 29.0 30 ≤35 NR <12 <12 <12


Graph computer or hand (C/H) C C C NR C/H C/H C/H

Loads in ( N or kN ) kN kN N kN kN kN kN

0 0 0 0 0 0.00 0.00 0.01

0.5 0.025 1.030 690 0.6 0.04 0.08 0.06

1 0.084 2.142 1350 1.3 0.12 0.19 0.16

1.5 0.189 3.533 2120 2.7 0.28 0.42 0.38

2 0.323 4.545 2990 4.6 0.64 0.86 0.82

2.5 0.542 5.777 3900 6.5 1.24 1.49 1.49

3 0.844 6.829 4820 8.4 2.05 2.29 2.37

3.5 1.211 7.427 5760 9.9 3.04 3.22 3.45

4 1.694 8.234 6740 11.5 4.18 4.26 4.54

4.5 2.166 8.697 7760 14.0 5.46 5.36 5.72

5 2.722 8.95 8730 16.5 6.81 6.48 6.92

6 3.977 9.404 10600 18.6 9.41 8.59 9.22

7.5 6.535 10.012 13290 24.6 13.05 11.61 12.52

8 7.195 10.370 14130 26.0 14.20 12.59 13.64

10 9.836 NR 17620 31.6 18.74 16.61 17.8710.512.5 12.660 NR 21960 36.2 24.71 21.65 23.47


Number 1 2 3 4 5 6 7

6 Particpants Test Results - Sample B

Table 1 of 7Note: Blank or NR = No result returned, Green are calculated/corrected results by PT coordinator.




Moisture-Before compaction - W1 (%) 8.2 8.1 8.3 8.3 8.1

Moisture Content Variation - Wv (%) -0.3 -0.4 0.2 0.2 04

Compaction (Manual or Auto) M M M M M

Compaction Method - Standard (Y/N) Y Y Y Y Y

No. blows per layer 53/53/53 53/53/53 25/25/25 40/40/40 53/53/53

Dry Density g/cm3

2.094 2.094 2.090 2.088 2.085

Density Ratio (LDR) % 100.4 100.4 100.2 100.1 100.3

Moisture Ratio (LMR) % 96.5 95.3 97.7 97.6 99.6

BR @ 2.5 mm (%) 44.7 43.1 44.1 42.3 43.0

BR @ 5.0 mm (%) 57.6 53.5 56.6 54.9 56.3

CBR (%) 57.6 53.5 56.6 54.9 43.0

Correction (mm) 2.10 2.10 0.5 0.7 3

Swell (%) 0.0 0.0 -0.1 -0.2 0.0

Moisture ww 8.2 8.1 9.1 9.0 8.7

Moisture w30 8.7 8.7 9.2 8.9 8.8

Moisture wr 7.8 7.9 NR 8.3 8.5

Date last calibrated 27/06/17 27/06/17 12/07/17 30/05/17 14/06/16

Calibrated range (kN) 50kN 50kN 0-50kN 0-50kN 0-50kN

Load cell (C) or ring (R) C C C C C

Calibration Class (AA, A, B, C etc) C C A A A

Hand driven (H) or motorised (M) M M M H M


Average 0.999 0.999 1.13 1mm/min NR

Lowest 0.983 0.983 1.13 1mm/min NR

Highest 1.02 1.02 1.13 1mm/min NR

Condition of material Good Good Satisfactory Damp OK

Seating load applied (N) 0.01 0.01 Y 0.050kN <50

Seating load set to zero (Y/N) Y Y Y Y Y

LL determined by clause(5d)1, 2 or 3 3 3 3 3 3

LL value used <12 <12 30 <35 ≤35

Period Cured (hours) 2 2 72 24 12

Graph computer or hand (C/H) C/H H C C C

Loads in ( N or kN ) kN kN N kN N

0 0.01 0.01 0 0.000 50seat

0.5 0.06 0.06 500 0.508 76

1 0.15 0.16 1340 1.255 137

1.5 0.34 0.36 2420 2.096 262

2 0.73 0.76 3510 3.103 478

2.5 1.38 1.36 4720 4.120 823

3 2.25 2.09 5820 5.171 1313

3.5 3.28 2.96 6950 6.287 1965

4 4.41 3.99 8170 7.402 2726

4.5 5.57 5.02 9150 8.502 3628

5 6.80 6.24 10270 9.488 4626

6 9.05 8.32 12100 11.601 5671

7.5 12.29 11.48 14940 14.580 10072

8 13.52 12.56 15700 15.619 11138

10 17.52 16.53 19000 19.273 1538210.512.5 23.28 21.84 22590 24.223 NR


Number 8 9 10 11 12 13 14


6 Particpants Test Results - Sample B 6 Particpants Test Results - Sample B

Table 2 of 7





Moisture Content Variation - Wv (%) -0.3 0.0 2.9 0.2 0.0 0.2 0.4

Compaction (Manual or Auto) M A M M M M M



Dry Density g/cm3

2.091 1.927 2.070 2.090 2.085 2.086 2.086

Density Ratio (LDR) % 100.3 100.3 99.3 100.3 100 100.0 100.0

Moisture Ratio (LMR) % 96.5 99.9 100.5 97.6 100 97.6 95.3

BR @ 2.5 mm (%) 51.1 28.6 0.780 56.1 50.2 33.8 42.5

BR @ 5.0 mm (%) 65.0 32.8 3.110 68.7 59.6 57.9 59.8

CBR (%) 65.0 32.8 15.8 68.7 59.6 57.9 59.8

Correction (mm) 0.91 0.35 1 1.8 1.6 0.0 1.0

Swell (%) -0.5 0.0 0 0.0 -0.1 0.0 0.0

Moisture ww 8.6 10.7 101.4 9.2 8.9 9.1 8.3

Moisture w30 8.5 10.0 9.2 8.2 8.6 9.0 9.1

Moisture wr 8.3 9.6 8.7 9.2 8.2 8.6 8.5


Calibrated range (kN) 0-50kN 0-100kN 0-50kN 0-40kN 1-50kN 50kN 0.045-50kN

Load cell (C) or ring (R) C C R C C C C

Calibration Class (AA, A, B, C etc) A A AA A A NR A

Hand driven (H) or motorised (M) M M M M H M M


Average NR 0.98 Average 1mm/min 1mm/min 0.94 1mm/min

Lowest 1.00mm 0.93 NR NR NR 0.83 NR

Highest 0.8mm/min 1.01 NR NR NR 1.14 NR

Condition of material Dry Moist Sealed Good Dry Dry Good

Seating load applied (N) 250N 50N dial gauge 250 50N 50N 0.045



LL value used ≤35 19 ? ? Medium NP 25


Graph computer or hand (C/H) C C C C C C NR

Loads in ( N or kN ) N N kN N N N kN

0 NR 1 0.01 0 0 0 0.00

0.5 538 319 0.017 301 282 496 0.160

1 1279 1102 0.049 769 717 1121 0.500

1.5 2220 1885 0.1 1415 1420 2066 1.100

2 3050 2642 0.181 2252 2217 3170 2.100

2.5 4450 3335 0.308 3253 3162 4457 3.150

3 5681 3968 0.504 4308 3963 5811 4.400

3.5 6949 4582 0.780 5448 5386 7200 5.650

4 8265 5125 1.089 6654 6336 8650 6.950

4.5 9491 5680 1.456 7881 7555 10053 8.200

5 10721 6201 1.930 9162 8569 11476 9.550

6 13162 7069 3.115 11703 10862 13970 11.950

7.5 16642 8270 5.055 15370 13167 17775 15.120

8 17651 8639 5.795 16570 13874 19181 16.170

10 22089 9943 8.950 21260 16448 23695 20.60010.512.5 27440 11290 12.888 27250 19106 29879 24.900


Number 15 16 17 18 19 20 21



Table 3 of 7




Moisture-Before compaction - W1 (%) 8.6 6.1 8.7 8.4 8.3 8.5

Moisture Content Variation - Wv (%) -0.1 -2.4 0.2 0.1 -0.2 0.0

Compaction (Manual or Auto) M M A M M M

Compaction Method - Standard (Y/N) Y Y Y Y Y Y

No. blows per layer 30/25/20 53/53/53 26/26/31 25/25/25 41/40/40 53/53/53

Dry Density g/cm3

2.077 2.090 2.081 2.068 2.087 2.102

Density Ratio (LDR) % 99.6 100.2 99.8 99.2 100.1 100.8

Moisture Ratio (LMR) % 101.2 97.6 102.4 98.6 97.6 100.0

BR @ 2.5 mm (%) 40.5 30.3 33.3 34.0 25.8 33.8

BR @ 5.0 mm (%) 50.2 39.9 39.7 39.2 35.9 56.9

CBR (%) 50.2 39.9 39.7 39.2 35.9 56.9

Correction (mm) 0.3 2.7 0.4 0 1.8 2.2

Swell (%) -0.0 1.3 0.0 -0.2 0.0 -0.5

Moisture ww 9.6 8.4 9.2 9.8 9.3 8.1

Moisture w30 9.2 8.2 9.9 9.5 9.3 8.6

Moisture wr 8.6 8.4 8.4 9.1 9.3 7.9


Calibrated range (kN) 0.001-50kN 4-1500kN 50kN 50kN 50kN 0-50kN

Load cell (C) or ring (R) C C R C C C

Calibration Class (AA, A, B, C etc) A A A A A/B A

Hand driven (H) or motorised (M) M H M M M M


Average 0.978 1mm/min 1mm/14sec 1mm/sec 1mm/min 1.000

Lowest 0.92 1mm/min 1mm/1sec NR 1mm/min 0.998

Highest 1.02 1mm/min 1m/30sec NR 1mm/min 1.001

Condition of material Good Moist Moist Moist OK Dry

Seating load applied (N) 50N -0.015 59.5 250N 45N 0

Seating load set to zero (Y/N) Y Y N Y Y Y

LL determined by clause(5d)1, 2 or 3 1 NR 1 3 3 ≤35

LL value used <17 NR 21.4 ? <35 ≤35


Graph computer or hand (C/H) C NR C C H C

Loads in ( N or kN ) kN kN N kN kN N

0 0.0 0.01 59.5 0.01 0.02 0

0.5 0.587 0.029 533 0.678 0.11 129

1 1.511 0.097 1231 1.642 0.31 299

1.5 2.604 0.252 2027 2.672 0.57 583

2 3.690 0.516 2889 3.612 0.92 1020

2.5 4.738 0.885 3738 4.492 1.35 1557

3 5.725 1.326 4613 5.242 1.83 2216

3.5 6.694 1.888 5449 5.968 2.38 3035

4 7.631 2.475 6245 6.629 2.95 4066

4.5 8.502 3.124 6975 7.192 3.58 5120

5 9.427 3.755 7738 7.770 4.25 6232

6 11.111 5.211 9140 8.871 5.73 8504

7.5 13.558 7.370 11596 10.213 8.16 12286

8 14.357 8.094 12591 10.570 8.96 13402

10 17.371 11.266 14819 12.134 12.34 1805810.512.5 21.361 15.223 16952 13.762 16.43 23518


Number 22 23 24 25 26 27 28



Table 4 of 7






Moisture Content Variation - Wv (%) 0.1 0.3 0.1 0.2 0.0 0 0.1

Compaction (Manual or Auto) A M M M M A M



Dry Density g/cm3

2.086 2.091 2.081 2.088 2.088 2.086 2.086



BR @ 2.5 mm (%) 44.8 45.2 46.2 51.2 32.0 41.0 57.9

BR @ 5.0 mm (%) 59.6 58.9 60.6 66.3 41.0 51.4 66.1

CBR (%) 59.6 58.9 60.6 66.3 41.0 51.4 66.1

Correction (mm) 1.5 2.5-3.8mm 1.2 1.5 3.0 0.3 3.5

Swell (%) -0.3 0.0 -0.1 -0.2 0.0 0.0 -0.4

Moisture ww 9.2 8.4 9.4 9.3 8.5 9.6 9.0

Moisture w30 8.9 8.0 9.0 8.6 8.8 9.0 111.1

Moisture wr 8.7 7.8 NR NR NR 8.4 93.4


Calibrated range (kN) 0-100kN 0-50kN 0-50kN 0-50kN 0-50kN 2-50kN 2-50kN


Calibration Class (AA, A, B, C etc) A A/B/C A A A A A



Average 1.01 0.98 NR NR 0.96 1mm/min 0.93

Lowest 0.94 0.99 1.0 1.0 0.88 NR 0.88

Highest 1.07 1.02 1.0 1.0 1.05 NR 1.00

Condition of material Moist Good Moist Moist Moist Moist Drier

Seating load applied (N) 0.15kN 0.045kN 50N 50N 45N 0.05N 20N

Seating load set to zero (Y/N) Y N Y Y Y Y Y


LL value used <35 low ? sand/gravel <35 LowLL <35


Graph computer or hand (C/H) C C C/H C/H C/H C C

Loads in ( N or kN ) kN kN N N N kN kN

0 0.00 0.255 0 0 0 0 0.02

0.5 0.23 1.402 195 150 65 0.67 0.08

1 0.61 2.252 592 485 167 1.60 0.20

1.5 1.20 3.227 1274 1069 326 2.66 0.39

2 1.89 4.299 2148 1948 542 3.75 0.73

2.5 2.72 5.460 3208 3058 835 4.83 1.25

3 3.67 6.653 4401 4283 1250 5.87 1.88

3.5 4.78 7.820 5611 5498 1662 6.85 2.64

4 5.91 8.976 6830 6754 2109 7.78 3.52

4.5 7.12 10.092 8003 7973 2850 8.73 4.51

5 8.32 11.193 9171 9248 3490 9.65 5.55

6 10.71 13.384 11549 11808 4957 11.31 7.66

7.5 13.94 16.446 14833 15286 7317 14.14 11.00

8 14.99 17.402 15869 16459 8109 15.03 12.14

10 19.21 21.193 19828 20763 11211 18.21 16.2510.512.5 24.28 26.111 24840 25398 13917 22.00 21.44


Number 29 30 31 32 33 34 35

Note: Blank or NR = No result returned, Green are calculated/corrected results by PT coordinator. Table 5 of 7






Moisture Content Variation - Wv (%) 99.6 0.0 0.1 0.2 0.1 0.0 0.0



No. blows per layer 35/35/35 NR NR 53/53/53 NR 25/25/25 52/53/48

Dry Density g/cm3

2.086 2.084 2.08 2.089 2.082 2.085 2.085

Density Ratio (LDR) % 100.1 100 100 100.2 99.9 100 100

Moisture Ratio (LMR) % 105.0 100 99 97.6 98.8 100 99.9

BR @ 2.5 mm (%) 47.1 41.5 35 11.2 45 48.1 38.3

BR @ 5.0 mm (%) 58.2 54.3 45 26.7 60 62.0 51.3

CBR (%) 58.2 54.3 45 26.7 60 62.0 51.3

Correction (mm) 1.8 2.5 0.5 0 1.6 1.1 1.8

Swell (%) -0.6 0.0 0.0 -0.4 -0.2 -0.6 -0.3

Moisture ww 8.5 9.1 8.6 8.8 8.1 8.7 NR

Moisture w30 8.7 8.8 9.1 8.5 8.7 9.0 8.9

Moisture wr 8.2 8.0 NR 8.2 8.3 7.6 7.9


Calibrated range (kN) 2-50kN 50kNx0.001kN 0.2-40kN 0-50kN 50kNx0.01kN 50kN 50Kn


Calibration Class (AA, A, B, C etc) A A A C B/A C A



Average 0.99 1.01 NR NR 0.980 1.00 1.2

Lowest 0.98 0.91 NR NR 1.017 0.96 NR

Highest 1.02 1.06 NR NR 0.943 1.00 NR

Condition of material Damp Good Good OK OK Dry Moist

Seating load applied (N) 0.03 18N 40kN 0.050kN 30N 250N 50kN

Seating load set to zero (Y/N) N Y Y Y Y Y Y

LL determined by clause(5d)1, 2 or 3 3 NR 3 1 16 1 NR

LL value used <35 20 No 18 16 <35 NR

Period Cured (hours) 69 55 24 48 72 48 NR

Graph computer or hand (C/H) C H/C C C C C C

Loads in ( N or kN ) kN N kN kN N N N

0 0.03 0 0.0 0.000 0 0 0

0.5 0.34 44 0.17 0.112 60 209 80

1 0.64 148 0.53 0.282 320 489 280

1.5 1.14 352 1.12 0.558 800 942 590

2 1.87 693 1.84 0.935 1540 1497 1060

2.5 2.72 1173 2.72 1.476 2500 2181 1710

3 3.7 1834 3.68 2.113 3550 3018 2530

3.5 4.63 2548 4.63 2.876 4690 4020 3460

4 5.67 3432 5.57 3.637 5940 5023 4460

4.5 6.73 4434 6.56 4.467 7170 5927 5490

5 7.79 5476 7.54 5.318 8410 6830 6520

6 9.95 7648 9.45 7.018 10680 9020 8570

7.5 13.2 10758 12.25 9.843 14000 11211 11530

8 14.11 11794 13.23 10.876 15050 12130 12530

10 18.05 15532 16.69 14.368 19140 15809 1639010.512.5 23.41 19399 21.15 18.876 23970 20263 21550


Number 36 37 38 39 40 41 42



Table 6 of 7



Code J3

Moisture-Before compaction - W1 (%) 8.5

Moisture Content Variation - Wv (%) 0.0

Compaction (Manual or Auto) M

Compaction Method - Standard (Y/N) Y

No. blows per layer 50/52/50

Dry Density g/cm3

2.085

Density Ratio (LDR) % 100.0

Moisture Ratio (LMR) % 100.0

BR @ 2.5 mm (%) 36.7

BR @ 5.0 mm (%) 48.8

CBR (%) 48.8

Correction (mm) 2.1

Swell (%) -0.2

Moisture ww 9.5

Moisture w30 8.8

Moisture wr 8.4

Date last calibrated 29/05/15

Calibrated range (kN) 0-90

Load cell (C) or ring (R) C

Calibration Class (AA, A, B, C etc) A

Hand driven (H) or motorised (M) M


Average 1.0mm/min

Lowest 1.0mm/min

Highest 1.0mm/min

Condition of material Suitable

Seating load applied (N) 30N

Seating load set to zero (Y/N) Y

LL determined by clause(5d)1, 2 or 3 3

LL value used low

Period Cured (hours) 120

Graph computer or hand (C/H) C

Loads in ( N or kN ) N

0 0

0.5 129

1 345

1.5 706

2 1243

2.5 1927

3 2711

3.5 3562

4 4477

4.5 5415

5 6415

6 8353

7.5 11232

8 12154

10 1576110.512.5 20197

Code J3 0 0 0 0 0 0

Number 43 44 45 46 47 48 49



Table 7 of 7



74 App A CBR PT Instructions V3.docx

LabSmart Services

Proficiency Testing Program

California Bearing Ratio – 2017 (74)

INSTRUCTIONS FOR TESTER

1. Please check that the package you have received contains the following:

➢ Instructions (for tester) ➢ Results Log ➢ Approximately 15.5 kg of soil sealed in a plastic bag labelled ‘2017 (74) CBR Sample’

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 17 October 2017.

4. Due to the possibility of segregation during transportation mix the sample thoroughly

prior to testing.

5. Split the sample into two equal portions, Sample A and Sample B. Keep in a sealed container.

6. There is no oversize material present in this sample. 7. You do not need to be accredited for AS 1289 6.1.1. You may use other equivalent

methods but it is preferable that AS 1289 6.1.1 be used.

8. Conduct the CBR test to AS 1289 6.1.1 (2014) with the 2017 amendment using the following information.

➢ Use an OMC of 8.5 %.

➢ Adjust the moisture of the sample as per the test method mixing thoroughly at

intervals . This should be done in a plastic bag with the end tied/folded over or

similar.

➢ As per clause 6(c) of the test method just prior to compaction take a sample to

determine final moisture content (w1) has been achieved i.e. OMC ± 0.5%.

➢ Sample to be remoulded at 100% standard compaction.

➢ Use a MDD of 2.085 t/m3

➢ LDR be within 100 ± 1.0%

➢ Apply a 4.5 kg surcharge.

➢ Soak the sample as per the method for 4 days.

➢ Swell is to be determined.

➢ Take additional load readings at 3.5, 4.5, 6.0 and 8.0 mm penetration.

Page 1 of 2

Appendix A



74 App A CBR PT Instructions V3.docx

9. Repeat the test as per step 7 to obtain two sets of results. The same person should complete both tests.

10. Please study the “Results Log” carefully before beginning the test.

11. Record the results on the enclosed “Results Log”. Report each result according to the log sheet. This will be different to the test method.

12. The Laboratory Manager or person responsible for checking must sign the log sheet to

indicate that it has been checked.

13. Please retain any unused sample until the final report has been issued.

14. Have a query? Contact Peter Young at LabSmart Services. Phone. 0432 767 706

15. Fax or e-mail the “Result Log” to LabSmart Services by 17 October 2017.

Fax: (03) 8888 4987 OR

E-mail: [email protected]

16. Please retain the completed “Results Log” as this contains your confidential

participation code. You will need this code to 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.

17. 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 testing program.

Page 2 of 2



74 App B CBR PT Results Log V3.docx

LabSmart Services

Proficiency Testing Program - California Bearing Ratio – 2017 (74)

RESULTS LOG for xxxx

Participation Code: xx

Please fax or e-mail the completed results log by 17 October 2017

E-mail: [email protected] or Fax: (03) 8888 4987

1. Please follow the instructions carefully. The test is to be performed twice and the

results entered into sections 3 and 4 below.

2. Please describe the characteristics of the CBR machine used for the tests:

Date last calibrated

Calibrated range (I.e.0-50 kN)

Load Cell or Load Ring?

Calibration (Class A, B, C?)

Hand driven or motorised platform?

Rate of penetration: Average / Lowest / Highest?

Please complete the following regarding the performance of the test

➢ Condition of material as received

➢ Seating load used

➢ Has the seating load been set to zero? (Y/N)

➢ LL determined by Clause 5(d) (i), (ii) or (iii)

➢ LL value used

➢ Period cured for? (hours)

3. Please attach a copy of the CBR graph for each test. 4. COMMENTS: (Please ensure all 6 sections are completed)

……………………………………………………………………………………………………………………………………………………………………………………………………………………

------------------------------------ ---------------------------------- --------------- 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 these sheets for your records.

________________________________________________________________________

Have a query? Contact Peter on 0432 767 706. Page 1 of 3

Appendix B



mailto:[email protected]


5.

SAMPLE A Report

To Result

Test Method Used

Tested by: Name

Moisture (Clause 6[c]) (W1) (before compaction)

0.1 %

Moisture content variation (Wv) 0.1 %

Compaction Manual or Auto

Compaction Method Standard (Y/N)

Number of blows used per layer Number

Before Soaking

Dry density 0.001 g/cm3

Density Ratio (LDR)

0.1 %

Moisture Ratio (LMR)

0.1 %

BR @ 2.5 mm 0.1 %

BR @ 5.0 mm 0.1 %

Correction# 0.1 mm

Swell 0.1 %

After soaking

Moisture ww 0.1 %

Moisture w30 0.1 %

Moisture wr 0.1 %

# Enter zero if no correction is performed.

Please record the penetration/ load readings below (cross out and change if other

penetration values are used) OR attach worksheet for with penetration/load readings.

Penetration (mm)

Load (N)

Penetration

(mm) Load (N)

0 4.0

0.5 4.5

1.0 5.0

1.5 6.0

2.0 7.5

2.5 8.0

3.0 10.0

3.5 12.5

Page 2 of 3




6.

SAMPLE B Report

To Result

Test Method Used

Tested by: Name

Moisture (Clause 6[c]) (W1) (before compaction)

0.1 %

Moisture content variation (Wv) 0.1 %

Compaction Manual or Auto

Compaction Method Standard (Y/N)

Number of blows used per layer Number

Before Soaking

Dry density 0.001 g/cm3

Density Ratio (LDR)

0.1 %

Moisture Ratio (LMR)

0.1 %

BR @ 2.5 mm 0.1 %

BR @ 5.0 mm 0.1 %

Correction# 0.1 mm

Swell 0.1 %

After soaking

Moisture ww 0.1 %

Moisture w30 0.1 %

Moisture wr 0.1 %

# Enter zero if no correction is performed.

Please record the penetration/ load readings below (cross out and change if other

penetration values are used) OR attach worksheet for with penetration/load readings.

Penetration (mm)

Load (N)

Penetration

(mm) Load (N)

0 4.0

0.5 4.5

1.0 5.0

1.5 6.0

2.0 7.5

2.5 8.0

3.0 10.0

3.5 12.5

Page 3 of 3



Appendix C – Graph Example

Calculate correction line from: Correction = 1.1 mm

Lower = 3.0 mm BR @ 2.5 mm = 43.3 % Unrounded CBR = 57.5 %

Upper = 6.0 mm BR @ 5.0 mm = 57.5 % CBR = 60.0 %

y = 2.4169x4 - 68.849x3 + 604.68x2 + 196.34x - 20.964R² = 0.9999

02,0004,0006,0008,000

10,00012,00014,00016,00018,00020,00022,00024,00026,00028,00030,00032,00034,00036,00038,00040,00042,00044,000

0 1 2 3 4 5 6 7 8 9 10 11 12

Ap

plie

d L

oad

(N

)

Penetration (mm)

CBR Graph for Participant X

Data Values

Poly. (Data Values)

Correction



Appendix D – CBR Measurement Uncertainty

It is not the intention of this proficiency program to calculate ‘measurement uncertainty’

(MU) for the CBR test. Discussing MU in relation to the CBR test is helpful in

identifying the components that contribute to and influence the MU. It is a useful tool

that can be used to better understand the test method and help reduce the spread

(variation) of CBR results.

The MU discussed in this section has been simplified for discussion purposes. For

example, the use of a linear equation would only be applicable in some circumstances.

The concept “direct” and “indirect” have been introduced here as a means of

demonstrating a concept.

The calculation of a MU for CBR can be discussed in terms of two components:

CBRMU = CBR CBR D + CBRCBR I

CBR – Direct Influences

The load/penetration graph for this program can be simplified and expressed in the

form y=mx +c.

Y = M by X + C

Load(@5mm) = Gradient

(load/penetration) Penetration at 5 mm

+ Zero correction Zero correction

Where the CBR = [ Load(@5mm) x 100 / 19.8 ] ± CBRCBR D

Both “19.8” and “100 “ are constants and have no uncertainty attributed to them.

There are several uncertainties that can be directly related to or directly influence

the ‘Load’ and ‘Penetration’ measurements:

➢ Accuracy of the load cell

➢ Accuracy of seating load

➢ Accuracy of penetration

➢ Accuracy of the rate of penetration

➢ Accuracy of recording force readings

➢ Number of data points selected

➢ Accuracy of the graph prepared

➢ Accuracy of the zero correction

➢ Rounding of results

The magnitude of these influences on a load or penetration can usually be directly

measured, calculated or estimated.



Appendix D – CBR Measurement Uncertainty

CBR – Indirect Influences

The MU calculations involving ‘indirect influences’ is added to the MU estimate as

shown in ‘gold’.

CBRMU = MUCBR D ± MUA ± MUB ± MUC etc.

The effect of indirect influences on the CBR MU calculated cannot be measured or

directly calculated. These indirect influences are estimated or determined

experimentally. They can be grouped as CBRCBR I.

To either estimate or determine experimentally usually requires that each influence

can be separated. For the CBR test it is neither practical (very costly) or possible in

most instances to do this. Indirect uncertainties for the CBR relate to both the effects

to the CBR result and the determination of:

➢ OMC & MDD

➢ Moisture content

➢ LDR & LMR

And the associated effect on MU of:


➢ Compaction i.e. layer thickness, compaction pattern, number of blows, achievement of

LDR & LMR

➢ Soil characteristics

A further difficulty in determining or isolating these indirect influences is that they can

interact with each other in unknown ways. For example, how a low MC with excessive

number of compaction blows affects the BR measurement is impractical to determine.

Another difficulty is that many of these measurements are subject to a natural variation

as well from one participant to another, compounding the problem of performing any

realistic comparison.

Summary

Direct uncertainty components can be measured or estimated. Testing can be

improved by reducing these and strict adherence to the test method.

Indirect uncertainty components can not be improved easily. Test variation is

minimised by strict adherence to the test method.



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