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EAPICto prove the skills of the laboratories

Summary: The quality process requires laboratories to prove their skills. Among themeans available, inter-comparison experiments are tools which are commonlyaccepted. Theywere expectedby the profession in the field of roadmaterials, but issuesrelated with volumes and the guarantee of sample homogeneity had delayed theirapplication. The EAPIC (Essai d’Aptitude Par Inter-Comparaison, Ability experiment byInter-Comparison) attempted to meet this expectation. This information note describesthe EAPIC process, a specialized group of the Qualification-Certification sectorcommittee of the CFTR. The EAPIC is in charge of organizing ‘round robin tests’ in thefield of road materials (asphalt mixtures, materials treated with hydraulic binders,aggregates…). The test campaigns allow the laboratories to check the quality of theirresults, by comparison with ‘real’ values, when they exist, or average conventionalvalues obtained by all laboratories. If applicable, statistical processing then showsvalues different from current results.

Six sessions were organized, including determination of binder content and sieve sizeanalysis of asphalt samples, repeated three times. Two hundred participations wererecorded for all these sessions. The main results for repeatability, reproducibility, andif applicable difference against ‘real’ values, are presented.

N°19June 2009

Association ruled by the Act of 1 July 1901

Members of CFTR : Assemblée des Départements de France - Association Française des Producteurs de Géotextiles et produits Apparentés - Association des Sociétés Françaisesd’Autoroutes - Association Technique de l’Industrie des Liants Hydrauliques - Centre Technique et de Promotion des Laitiers Sidérurgiques - Chambre Syndicale Nationale desFabricants de Chaux Grasses et Magnésiennes - Comité Infrastructure de Syntec Ingénierie - Direction des Infrastructures de Transport – Direction de la Sécurité et de la CirculationRoutières – Groupement Professionnel des Bitumes – Laboratoire Central des Ponts et Chaussées - Service d'Etudes sur les Transports, les Routes et leurs Aménagements – Service Techniquede l'Aviation Civile - Syndicat des équipements pour Constructions Infrastructures Sidérurgie et Manutention - Syndicat Professionnel des Entrepreneurs de Chaussées en Béton etEquipements Annexes - Syndicat Professionnel des Terrassiers de France - Union Nationale des Producteurs de Granulats - Union des Syndicats de l’Industrie Routière Française.

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1 - Introduction

Over the last few years, road-building professionshave focused on better control over qualityassurance.

The first step taken was to standardize tests in roadconstruction and determine values for methodrepeatability and reproducibility. The second stepresulted in the certification or accreditation of anincreasing number of road constructionlaboratories.

The third consists in validating for specific tests theperformance of laboratories, allowing them todemonstrate reliability to their clients and stillimprove result quality through corrective action.The method is based on inter-comparison abilitytests (round robin tests). In addition to thisobjective, inter-comparison experiments improvetest methods, confirm or improve reproducibilityvalues, while appreciating the effectiveness of newmethods.

In the field of road infrastructures, test campaignsof this type are organized regularly for hydrocarbonated binders, cements and a few otherproducts. In spite of strong demand, there are nointer-comparison experiments for materials treatedwith hydro carbon or hydraulic binders, probablybecause of the ‘weight’ of the organisationrequired.

The EAPIC specialized group attempted to resolvethis shortcoming. It was implemented late 2001,and ran the first test campaign in 2002. Since then,EAPIC has led the following campaigns:

• Determination of soluble binder content of anasphalt mixture, as per the European standardand associated sieve size analysis,

• Measurement of maximum density of abituminous mixture and gyratory shear presscompaction,

• Los Angeles and Micro-Deval experiments,

• Methylen blue test and flow-test for fineaggregate.

This note describes the structure of the EAPIC andits operation, and presents a summary based onexamples of results of the test campaigns led.

2 - The E.A.P.I.C specialized group

The ‘Essais d'aptitudes par inter-comparaison’(inter-comparison collaborative experiments)specialized group reports to the Comité SectorielQualification – Certification (Qualification-Certification Sector Committee) of the CFTR.

It is composed of technical experts and qualiticiansfrom the public and private road constructioncommunity.

This group aims at organizing inter-comparisonexperiments on the ability of laboratories in thefield of road construction: asphalt mixtures,materials treated with hydraulic binders.

The specialized group is the decision authority,supported by an executive cell in charge oforganizing the experiments. The logistic supportlinked with the preparation and procurement inmaterials or test specimens required for leading theinter-comparison experiments is ensured bysupport laboratories under the liability of theexecutive cell.

SUPPORT LABORATORYSelected according to the campaign.

For the first sessions, they are:Laboratoire Régional d’AutunLaboratoire Régional d’Angers

Laboratoire Régional de l'Est Parisien

EXECUTIVE CELLLaboratoire Régional de l’Est Parisien

Jean-Luc DELORMENicole VERCHERE

EAPIC SPECIALIZED GROUPChairman:

Jean-Eric POIRIERMembers:

Jean-Luc DELORMEIvan DROUADAINESylvain MOREIRA

Jean-Pierre TRIQUIGNEAUXNicole VERCHERELouisette WENDLING

QUALIFICATION – CERTIFICATIONSector Committee of CFTR

ChairmanHélène JACQUOT-GUIMBAL

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The specialized group is entrusted with choosingand planning the test campaigns, supervising theirperformance, validating the organizationprocedures, selecting the support laboratories andapproving and publishing the results.It also approves the amounts set for financialcontributions for participation in the tests andremuneration of the works.

The executive cell is in charge of organizing andcoordinating the test campaigns. It monitors testperformance and result processing. It issues callsfor applicants, prepares procedures, ships objectsto be tested, collects results, processes them andcommunicates them to each participant within therules of confidentiality set.

Support laboratories, selected by the specializedgroup, store the stocks of materials, prepare them,ensure controlled manufacturing of proofspecimens (replicas), demonstrate homogeneity,deliver to the participants in inter-comparisonexperiments. Action of support laboratories is ledaccording to a Quality Assurance Plan andperformance procedures with a content specifiedby the executive cell, and subject to approval bythe specialized group. They must be holders of aCOFRAC accreditation or a LABOROUTE approvalor ISO 9000 certification.

3 - Test campaigns

The test methods concerned are standardizedmethods in the road construction field: coatings,materials treated with hydraulic binders or nontreated, aggregates. Tests on bitumens areexcluded (Bureau de Normalisation des Pétroles)for which other provisions have already beenimplemented.

The group gives priority to standardizedexperiments, for which repeatability ‘r’ andreproducibility ‘R’ are known, which are the mostfrequently used as a value specified, and whichmay give rise to comparison within a contractualframe.

EAPIC has defined the ‘campaign’ as being a typeof test or a family of experiments. Campaigns aredivided into ‘sessions’. Each session is classifiedas an ‘operation’. Hence the ‘Binder content –Sieve size analysis’ campaign was subject to 3sessions in 2002, 2003 and 2007 and EAPICperformed 6 operations (3 ‘Binder content’

sessions, one ‘PCG’ session, one ‘LA-MDE’session, one ‘Blue-flow test’ session).

Selection of participantsA call to applicants is issued through professionalunions, the technical network and thestandardization commissions involved. Theparticipating laboratory commits to meet thedeadlines set, and apply the standard or operatingmethod specified.

Unlike procedures implemented for organizingprecision experiments, for which representativityof laboratories is required, the candidates areaccepted without selection draw (exceptexceptional case).

If the participating laboratories are too numerousagainst the constraints of an experiment (size ofstocks, performance time,…) the experiment canbe performed in two or several sessions.Performance in several sessions spreads the workload and offers more flexibility to participatinglaboratories. Conversely, if too few laboratories areincluded to a session, the latter may be cancelled.

Method for manufacturing objects subject totesting

Support laboratories prepare the objects to betested by applying procedures approved by thespecialized group. Quantities must consider thenumber of laboratories planned, the nature of thetest, number of replicas and conservatorymaterials to be used as reference afterinterlaboratory experiment. The main difficulty is toguarantee sample homogeneity, and also theirstability over time.

Precautions are applied as upstream as possiblefor supplying and manufacturing the samples.

Homogeneity is checked by samples and analyseson the stock made, as per the principles ofappendix B of standard ISO 13528.

Data analysis

Data analysis is performed by the executive cell,by applying documented procedures based on theNF ISO 5725 standard. Data are coded to ensureconfidentiality. The participating laboratories areinformed of the ‘true’ values, when they are known,their result is integrated to a general bar chartshowing all results or differences between realvalues and the average values obtained.

Example of customized histogram

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As defined by the NF ISO 5725 standard, thestatistical tests of COCHRAN’s test (dispersionvalues [intra-laboratory] aberrant on the 1%threshold) and GRUBBS’s test (average values[inter-laboratory] aberrant on the 1% threshold) are

applied to the test results. DIXON’s test detectsaberrant individual test values. Standard deviationand repeatability limit, as well as standarddeviation and reproducibility limit, are calculatedfor the parameter considered.

Soluble binder content deviation/true valueNF EN 12697-1

3rd session of campaign n° 1

-0,35

-0,30

-0,25

-0,20

-0,15

-0,10

-0,05

0,00

0,05

0,10

0,15

0,20

0,25

0,30

0,35

0,40

0,45

Q004 Q007 Q027 Q037 Q006 Q001 Q028 Q030 Q013 Q019 Q031 Q024 Q016 Q011 Q008 Q017 Q041Laboratoiries

Asphaltcontentdeviation

Série1

Série2

Série3

Série4

Cochran's test

Grubbs' test

Dixon's test

General average on rawresults

Laboratory n°Q 009

Laboratoryeliminated byGrubbs'test

Average corrected afterelimination aberrant

results 1 Std. Dev.

2 Std. Dev

1 Std. Dev.

2 Std. Dev.

Example of certificate

ATTESTATION

�ll�`l �_�pk`kj��p�m `tk�m�r\p�m�`lrt

1ère Campagne – 3ème Session – Série n°4

La participation du

LABORATOIRE ETUDES ROUTIERES

Pour les essais suivants :

Teneur en liant soluble selon la normeNF EN 12697-1 d’avril 2006

EtDétermination de la granulométrie selon la norme

NF EN 12697-2 de juin 2003

Réalisé sur le site :

75000 PARIS

A été enregistrée par la cellule exécutive de l’E.A.P.I.C sous le numéro W006

Les résultats fournis ont été traités conformément aux procédures internes de l’E.A.P.I.C.Les résultats complets de la session figurent dans le rapport n°1-3-004

L’attestation de participation à cette campagne d’essais a été délivrée le :

15 septembre 2008

La Président du Comité Sectoriel« Qualification - Certification »

Hélène JACQUOT-GUIMBAL

Comité Français pour les Techniques Routières – Secrétariat Permanent – 10, rue Washington – 75008 PARIS

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All these results are communicated to the participants, together with a customized participation certificatementioning the confidential code of the laboratory, to be situated in the bar charts.

Campaigns led

Since 2002, EAPIC has led 6 different operations, in 4 campaigns, one of which included 3 sessions.

The list of operations is given in table 1.

Campaign Opération Tests Test Session Number of Périod ofNr standard participants performance

1

2

3

4

1

2

5

3

4

6

Content in solublebinder

Sieve sizeanalysis

Maximum densityof bituminousmixtures

Gyratory shearpress compaction

Los Angeles test

Micro-Deval test

Methylen bluetest

Fine aggregatedensity

Fine aggregateflow test

EN 12697-1

P 18-560

EN 12697-1

P 15-560

EN 12697-1

EN 12697-2

EN 12697-5

EN 12697-31

EN 1097-1

EN 1097-2

EN 939-9

EN 1097-6

EN 933-6

EAPIC1.1

EAPIC1.2

EAPIC1.3

EAPIC2.1

EAPIC3.1

EAPIC4.1

31

28

41

28

39

65

(2 simultaneoussessions)

September2002 to

April 2003

September2003 to

June 2004

September2007 to

April 2008

November2004 to

June 2005

April2007 to

October 2007

October2008 to

May 2009

Table 1 – List of EAPIC operations led

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Example of results, deviation, repeatability ‘r’and reproducibility ‘R’ (change over 3sessions)

The campaign on determining soluble bindercontent and sieve size analysis was performed in3 sessions. The results of these 3 sessions aregiven in tables 2 to 4 for example ; they show thechange over these sessions.

Note: The units in test results for binder contentsand passing at different sieve size are expressed inpercentages. The average difference against thetrue value mentioned in the tables is the differencein absolute value between these percentages, andnot a relative difference, as could be deducted fromthe percentage expression alone. This is why theunits in the tables are expressed in ‘absolute %’.

EAPIC 1.1 30 - 0,15 0,21 0,35

EAPIC 1.2 23 - 0,125 0,18 0,22

EAPIC 1.3 35 - 0,03 0,23 0,31

Table 2 – Campaign 1 – Content in soluble binder as per EN 12697-1

EAPIC 1.1 29 0,1 0,9 1,0

EAPIC 1.2 28 0,5 1,3 1,5

EAPIC 1.3 40 - 0,4 1,2 1,6

Table 3 - Campaign 1 – Sieve size analysis EN 12697-2 screened at 0.063 mm

Number ofnon-rejectedlaboratories

Difference betweenaverage and trueabsolute %value

repeatability‘r’

Absolute %

Reproducibility‘R’

Absolute %

Number ofnon-rejectedlaboratories

Difference betweenaverage and trueabsolute %value

repeatability‘r’

Absolute %

Reproducibility‘R’

Absolute %

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EAPIC 1.1 31 0,0 1,2 2,4

EAPIC 1.2 26 0,2 1,3 1,8

EAPIC 1.3 39 - 0,5 1,3 3,0

Table 4 - Campaign 1 – Sieve size analysis EN 12697-2 screened at 2.0 mm

EAPIC 1.1 31 1,6 3,0 4,3

EAPIC 1.2 27 1,0 2,5 3,9

EAPIC 1.3 39 - 0,6 3,1 5,2

Table 5 - Campaign 1 - Sieve size analysis EN 12697-2 screened at 6.0 mm

Comments

When determining binder content, we hadobserved over the first two sessions that thedifference between the ‘true’ value (componentsweighed) and the value measured by the analysisled (in absolute value) to an average difference of0.15 % or 0.125 %. During the last session, thisdifference was considerably reduced, close to

zero. No obvious explanatory factor appears, theaggregates have the same origin, an identicalreplica preparation method, performed by thesame support laboratory. The origin of the‘difference' observed during the first experimentsis currently unexplained, and we must chosecarefully the nature of materials and change inmethods of the next sessions on the subject.

Number ofnon-rejectedlaboratories

Difference betweenaverage and trueabsolute %value

repeatability‘r’

Absolute %

Reproducibility‘R’

Absolute %

Difference betweenaverage and trueabsolute %value

repeatability‘r’

Absolute %

Reproducibility‘R’

Absolute %

Number ofnon-rejectedlaboratories

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The last results show that the introduction of asystematic corrective value in analysis results isnot justifiable.

The differences and repeatability andreproducibility values do not show any noticeablechange over the 3 sessions.

Method validation

The equivalence between the methods used todetermine asphalt content, described explicitly inthe standard, such as cold dissolution, and themethod using automatic device wasdemonstrated thanks to the EAPIC results.

Binder content between the automatic devicemethod and the ‘classic’ cold dissolution method,leads to the same average difference against the‘true value’, dispersion during the 3rd sessionbeing slightly stronger than in the classic method.In sieve size analysis, a slight difference in finecontent of 0.3% was seen, a value which is lowerthan with the classic method. Uncertaintyestimated on the ‘real’ value of fines content doesnot allow to conclude that the result of one or theother method is closer.

EAPIC Identification NatureYear operation of the session of

Nr. campaign’s ability test the test

2009 EAPIC 8 E6.1 Wheel

2009 EAPIC 9 E7.1 Polishing stonePSV value

2010 EAPIC 10 E8.1 Water sensitivity

2010 EAPIC 11 E2.2 Giratory shearcompaction

2010 EAPIC 12 E1.4 Binder content,grading

Table 6 – The campaigns programmed

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4 - In practice

How to participate ?

� Visit the CFTR website: http://www.cftr.asso.fr/then ‘Produits’, then ‘Qualification-Certification’, then ‘EAPIC’.

� Future sessions are published at the time of callfor candidates in the RGRA magazine (RevueGénérale des Routes et Aérodromes).

� Directly: LREP the executive cell updates a listof ‘clients’, you may pre-register for the list, tobe informed of campaigns being launched, byaddressing your requests to:

Jean-Luc DELORMETel : +33 (0)1 60 56 64 53email:jean-luc.delorme@developpement-durable.gouv.fr

Nicole VERCHERETel : +33 (0)1 60 56 64 66email:nicole.verchere@developpement-durable.gouv.fr

Postal address:LREP - 319, avenue Georges ClemenceauBP 505 - 77015 MELUN CedexFax : +33 (0)1 60 56 64 01

Cost ?

Cost is determined by the expenses engaged forpreparing the objects submitted to the test, forlogistics, processing and publication of results,according to the number of participants expected.Work to be performed by the support laboratory isusually preponderant in this equation.

For information, during the campaigns led,participation was about:

- 1500 € excluding VAT for the campaign ‘Bindercontent – Grading analysis’,

- 2500 € excluding VAT for the campaign ‘Rotatingshearing press – Maximum density’

- 990 € excluding VAT for the campaign ‘LosAngeles + Micro-Deval’.

Satisfaction surveys

They are performed upon each operation. Theybear on the quality of relations with EAPIC, thetechnical skills, organisation, quality of the report,compliance with lead times.

➤ Legibility of reports is the main comment. Thebar charts were customized to better view thelaboratory results, an image of the populationhas been added. A new presentation is beingprepared for the next sessions, with a table ofdifferences against the conventional value.

5 - Summary and prospects

The first campaign ‘Binder content – Sieve sizeanalysis’, divided into 3 sessions, mobilised aboutone hundred participating laboratories.Campaigns dedicated to aggregates, Los Angeles,Micro-Deval, blue test, sand flow test also drewover a hundred candidates. This shows majorexpectations by the profession.

The large number of participants per session (atleast 30) allows representative statistical use.

EAPIC reports were appropriate tools during auditsfor accredited or certified laboratories.

EAPIC contributed to the application of Europeanstandards and their validation (e.g. Real density onmix).

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Glossary:

‘r’ repeatability: results obtained on the sameobject or a similar object in the same measuringconditions: measurement procedure, operators,measurement system, operating conditions,location, during a short period.

‘R’ reproducibility: results obtained on the sameobject or a similar object in different measurementconditions: locations, operators, measurementprocedure, measurement system, operatingconditions , but only for a short period of time.

Campaign: set of operations within a same type orfamily of experiments. A campaign is divided intoone or several sessions.

Operation: operations include launching a session,construction of replicas, collection and processingresults.

Replicas: individual samples produced by thesupport laboratory and considered as similar. Eachparticipating laboratory receives several replicas,usually 3 or 4.

Session: operation on a given test campaign.

Grubbs’ test: this statistical test, codified in theISO 5725 standard, allows detecting an outlyingaverage (1% threshold) among the population ofresults.

Cochran’s test: this statistical test, codified in theISO 5725 standard, allows detecting an aberrantdispersion (1% threshold) among the population ofresults.

Dixon’s test: this statistical test allows detecting anaberrant value isolated among the population ofresults.

True value: a ‘true’ value is a value known with alow uncertainty. For example, granular fractionsand quantity of binder in asphalt samples areweighed very precisely, and mixing devices are leftstored in containers to avoid losing bitumenparticles. Binder content is then considered as a‘true’ value to which the values measured can becompared.

Conventional value: for certain quantities, truevalues do not exist, e.g. material density. Theaverage value obtained during the session, afterremoving outliers values, is considered as beingthe conventional value.

This note was written by Jean-Luc Delorme (LREP) with the participation of the EAPIC group

Document produced and issued by the Comité Français pour les Techniques RoutièresCFTR - 10 rue Washington - 75008 PARIS - FrancePhone: 33 (0)1 44 13 32 87 - Fax: 33 (0)1 42 25 89 99Email: cftr@usirf.com - Web site: www.cftr.asso.fr Downloadable at www.cftr.asso.fr

Document reference: RI 0901

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