1、Designation: C802 14Standard Practice forConducting an Interlaboratory Test Program to Determinethe Precision of Test Methods for Construction Materials1This standard is issued under the fixed designation C802; the number immediately following the designation indicates the year oforiginal adoption o
2、r, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This practice describes techniques for planning,conducting, and analyzing the
3、 results of an interlaboratorystudy (ILS) with the objective of developing the precisionstatement of a test method. It is designed to be used inconjunction with Practice C670. The methods used in thisstandard are consistent with those in Practice E691.1.2 This practice is not intended for use in pro
4、grams whosepurpose is to develop a test method or to assess the relativevariability of two or more test methods. Refer to PracticeC1067 for procedures to evaluate the ruggedness of a testmethod.1.3 The system of units for this practice has not beenspecified. Dimensional quantities in the practice ar
5、e presentedonly in examples of calculations.1.4 This standard does not purport to address all safetyconcerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety andhealth practices and determine the applicability of regulatorylimitat
6、ions prior to use.2. Referenced Documents2.1 ASTM Standards:2C109/C109M Test Method for Compressive Strength ofHydraulic Cement Mortars (Using 2-in. or 50-mm CubeSpecimens)C136 Test Method for Sieve Analysis of Fine and CoarseAggregatesC311/C311M Test Methods for Sampling and Testing FlyAsh or Natur
7、al Pozzolans for Use in Portland-CementConcreteC670 Practice for Preparing Precision and Bias Statementsfor Test Methods for Construction MaterialsC1067 Practice for Conducting a Ruggedness Evaluation orScreening Program for Test Methods for ConstructionMaterialsE105 Practice for Probability Samplin
8、g of MaterialsE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE178 Practice for Dealing With Outlying ObservationsE456 Terminology Relating to Quality and StatisticsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology
9、3.1 Definitions:3.1.1 For definitions of general statistical terms, refer toTerminology E456.3.1.2 For definitions of terms associated with precision oftest methods for construction materials, refer to Practice C670.4. Significance and Use4.1 This practice provides requirements for planning andcondu
10、cting an interlaboratory study to obtain data to developsingle-operator and multilaboratory precision statements for atest method. It includes methods to evaluate data consistencybefore carrying out the calculations to develop the precisionstatement. The procedures are compatible with those in Prac-
11、tice E691.4.2 The ILS data obtained from this practice are intendedfor developing the precision values for writing single-operatorand multilaboratory precision statements in accordance withPractice C670.4.3 Appendix X1 provides an example to illustrate thecalculations to obtain the precision values
12、of the test methodfrom the ILS data. This may be used to check a user-developedelectronic spreadsheet for carrying out the calculations.4.4 Appendix X2 discusses the additional calculations re-quired for an interlaboratory study of a test method thatincludes making test specimens as part of the proc
13、edure. In thiscase, batch-to-batch variability needs to be considered.1This practice is under the jurisdiction of ASTM Committee C09 on Concreteand ConcreteAggregates. This practice was developed jointly byASTM CommitteeC01, C09, D04, and D18, and is endorsed by all four committees.Current edition a
14、pproved Dec. 15, 2014. Published June 2015. Originallyapproved in 1974. Last previous edition approved in 2009 as C802 09A. DOI:10.1520/C0802-14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards
15、volume information, refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14.5 Appendix X3 discusses the use of
16、analysis of varianceas an alternative approach to obtain the precision values fromthe ILS data.5. General Requirements5.1 Certain criteria need to be met before undertaking aninterlaboratory study to determine the precision of a testmethod. If some conditions are not met or are metincompletely, the
17、program will become more complicated toadminister and require more work and expense, or may resultin impaired information. The requirements outlined in thissection are intended to ensure that the test method is free oftechnical difficulties to the greatest extent possible before anexpensive and time
18、-consuming interlaboratory study is under-taken.5.2 The first requirement is the existence of a valid andwell-written test method that has been developed in onelaboratory and has been subjected to ruggedness evaluation ofthe testing procedure and conditions as described in PracticeC1067. As a result
19、 of the screening procedure and someexperience with the test method in the sponsoring laboratoryand one or two others, a written version of the test method hasbeen developed (but not necessarily published as a standard)that describes the test procedure in terms that can be followedby a competent ope
20、rator in any properly equipped laboratory.Critical conditions that affect the test results need to beidentified and the proper and realistic degree of control of thoseconditions have to be specified in the description of the testprocedure.5.2.1 The tolerances established for various conditions in at
21、est method provide reasonable ranges for these conditions andrecognize that precise values with small tolerances may not beachievable in practice. Variations in test results due to varia-tions in such conditions contribute to the total variation, whichdetermines the precision of the test method. If
22、the resultingvariation is so great that uncertainties in average valuesobtained by the test method are unacceptably high, the testmethod itself is at fault and it will need to be improved orreplaced by a better one. An expensive and time-consuminginterlaboratory study is not recommended for such a t
23、estmethod.5.2.2 Apparatus required for performing the test must bedefined clearly and must be available or able to be produced. Ifalternative apparatus is permitted, criteria need to be providedon the performance requirements of the apparatus, such as byspecifying acceptable limits of measurements o
24、n standardreference materials.5.3 Personnel in laboratories participating in the ILS shouldhave adequate experience with routine laboratory proceduresso that they are competent to run the test. The importance ofthis requirement will vary with the complexity of the methodand the degree to which it de
25、parts from familiar procedures.5.4 It is helpful to have preliminary knowledge about howchanges in materials and conditions affect the test results.There should be a reasonable degree of certainty that thesingle-operator variances are the same in different laboratories,and that troublesome interacti
26、ons do not exist. These condi-tions are investigated in the initial analysis of the data of aninterlaboratory study, and are discussed further in 10.4.5.5 Facilities and procedures for procurement, preparation,and distribution of samples or test specimens must be avail-able.5.6 Selection of samples
27、or test specimens must be done bya randomization process, and one person who is familiar withrandomization procedures needs to be responsible for seeingthat an appropriate randomization technique is used. Refer toPractice E105.5.7 The precision of the test method should be evaluated ondifferent mate
28、rials with a range of the characteristic beingmeasured that encompasses the typical use of the method inpractice. (See 7.1 and 7.2.)5.8 Adequate numbers of participating laboratories,operators, and materials must be available. Requirements inthese areas are specified in Sections 6 and 7.5.9 The enti
29、re interlaboratory test program should be devel-oped from the beginning with the help and advice of personsfamiliar with statistical procedures and with the materialsinvolved. The ASTM International Interlaboratory Study Pro-gram can support subcommittees in the development of preci-sion statements
30、by assisting in the design of an interlaboratorystudy, distribution of specimens or samples, data analysis, andpreparation of a draft research report. Additional informationabout theASTM ILS program can be obtained from theASTMWebsite.5.9.1 It may not always be possible to obtain people who arefamil
31、iar with the materials involved and who have a sufficientknowledge of the proper statistical techniques and their properuse. In this case, the subcommittee should obtain the servicesof a statistician who has experience in practical work with datafrom materials testing, and provide that person with a
32、nopportunity for learning something about the particular mate-rials and test method involved. Planners of an interlaboratorystudy need to avoid the pitfall of assuming that the use ofstatistical analysis software programs necessarily results inspecial expertise in manipulating the data or interpreti
33、ng theresults.5.10 It is important to bear in mind that estimates of theprecision of a test method are always based on a particular setof data obtained at a particular time and precision values needto be kept up-to-date. As materials, apparatus, and conditionschange, and operators change or gain mor
34、e experience, thecharacteristic precision of the results obtained may change,especially if the test method is new. In some cases, it may bedesirable to conduct more tests at a later date (though notnecessarily a repetition of the complete interlaboratory study)in order to provide a check on estimate
35、s previously obtainedand either verify them or introduce revisions. When a subcom-mittee revises a test method, it should consider whether theproposed changes might affect the precision of the method. Ifthere is a possibility that precision will be affected, limitedinterlaboratory testing is recomme
36、nded to evaluate whether theexisting precision statement is still applicable or if a new ILSneeds to be organized to better reflect the precision of therevised method.C802 1426. Laboratories6.1 Obtaining participating laboratories for an interlabora-tory study is often one of the most difficult prob
37、lems connectedwith the process. The number of laboratories available isseldom as extensive as one would like, and if the test methodis new, complicated, or expensive and time-consuming to run,the problem is further complicated.6.2 For the purposes of programs using this practice, it isrecommended th
38、at at least ten competent laboratories beincluded (1, 2).3In cases where it is impossible to obtain tenlaboratories, the effect of an increased number may be obtainedby repeating the program with the same group of laboratoriessix months later. If this procedure is followed, it is necessary tobe sure
39、 that the same materials are used, and that theircharacteristics have not changed in the interim. This approach,however, may not provide a proper measure of the between-laboratory component of variance, unless different operators orequipment, or both, are used for the repeat testing. In any case,six
40、 is the absolute minimum number of laboratories forevaluating the precision of a test method. This means that atleast seven to eight laboratories should be in the ILS study incase problems are encountered with the data provided by aparticipating laboratory.6.3 In general, it is recommended that any
41、laboratory that isconsidered qualified to run the test in routine testing situationsshould be permitted and encouraged to participate. “Qualified”implies proper laboratory facilities and testing equipment,competent operators familiar with routine laboratorytechniques, a history of reliable testing w
42、ork, and sufficienttime and interest to do a good job. It does not mean, however,that only a select group of laboratories that are considered to bethose best qualified for the interlaboratory study should bepicked. Precision estimates for inclusion in a test method mustbe obtained under conditions a
43、nd through the efforts oflaboratories and personnel that are representative of the situa-tions in which the test method will be used in practice (2).Ifalaboratory satisfies all the other requirements, but its personnelhas had insufficient experience with the method, the operatorsin that laboratory s
44、hould be given an opportunity to familiarizethemselves with the method and to practice its applicationbefore the interlaboratory study starts.7. Materials7.1 NumberThe number of materials to be included in aninterlaboratory study will depend on the following:7.1.1 The range of the values of the prop
45、erty that may bemeasured in practice and how the precision varies over thatrange;7.1.2 The types of materials to which the test method is tobe applied;7.1.3 The difficulty and expense involved in obtaining,processing, and distributing samples or specimens;7.1.4 The difficulty of, length of time requ
46、ired for, andexpense of performing the tests; and7.1.5 The uncertainty of prior information on any of thesepoints. For example, if it is already known that the precision isrelatively constant or proportional to the average level over therange of values of interest, a smaller number of materials will
47、be needed than if it is known that the precision changeserratically at different levels. A preliminary pilot or screeningprogram may help to settle some of these questions, and mayoften result in the saving of considerable time and expense inthe full interlaboratory study (1).7.2 In general, at leas
48、t three materials or three differentaverage values of the measured test characteristic is consideredacceptable. The materials need to be selected to obtain as broada range of the test characteristic as is practicable. If the testmethod is used to determine properties that are used foracceptance test
49、ing in a specification, it is particularly importantthat materials be included in the ILS whose properties are nearthe specification limits.7.3 Specimen DistributionThe ILS is based on the as-sumption that all tests are performed on specimens that are assimilar as is possible. Generally, two approaches are used formaking and distributing the specimens or materials for the ILS.7.3.1 For a test method that does not involve production ofthe test specimens as part of the method, specimens areproduced at one location from a homogenous sample and thendistributed to the participating l
