1、Designation: C1451 11C1451 18Standard Practice forDetermining Variability of Ingredients of Concrete Concrete-Making Materials From a Single Source1This standard is issued under the fixed designation C1451; the number immediately following the designation indicates the year oforiginal adoption or, i
2、n 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 covers a procedure for determining the variability of properties of
3、 concrete concrete-making materials froma single source. source by measuring a characteristic property of the material. It includes recommendations on sampling, testing,analysis of data, and reporting.1.2 The system of units for this practice is not specified. Dimensional quantities in the practice
4、are presented only as illustrationsUnits used in examples of calculation methods that are applicable independent of the system of are for illustration purposes. Thecalculation methods described in this practice can be used with either SI or inch-pound units.1.3 This standard does not purport to addr
5、ess all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine theapplicability of regulatory limitations prior to use.1.4 This international standar
6、d was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referen
7、ced Documents2.1 ASTM Standards:2C109/C109M Test Method for Compressive Strength of Hydraulic Cement Mortars (Using 2-in. or 50-mm Cube Specimens)C125 Terminology Relating to Concrete and Concrete AggregatesC219 Terminology Relating to Hydraulic CementC494/C494M Specification for Chemical Admixtures
8、 for ConcreteC917C917/C917M Test Method for Evaluation of Variability of Cement from a Single Source Based on StrengthD75D75/D75M Practice for Sampling AggregatesD3665 Practice for Random Sampling of Construction Materials3. Terminology3.1 Definitions:3.1.1 For definitions of terms relating to this
9、practice refer to Terminology C125 and Terminology C219.3.2 Definitions of Terms Specific to This Standard:3.2.1 grab sample, na specified quantity of material obtained in a single operation from a sampling unit.3.2.1.1 DiscussionThe goal of procuring a grab sample is to obtain a small portion of ma
10、terial that is characteristicrepresentative of that in thesampling unit.3.2.2 lot, na user-defined quantity, typically representing anythe amount of material for which variability information is to becalculated.determined.1 This practice is under the jurisdiction of ASTM Committee C09 on Concrete an
11、d Concrete Aggregates and is the direct responsibility of Subcommittee C09.94 onEvaluation of Data (Joint C09 and C01).Current edition approved July 1, 2011Jan. 1, 2018. Published August 2011February 2018. Originally approved in 1999. Last previous edition approved in 20052011 asC145105.11. DOI: 10.
12、1520/C1451-11.10.1520/C1451-18.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM s
13、tandard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all c
14、ases only the current versionof the standard as published by ASTM is to be considered the official document.*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 States13.2.2.1 Discu
15、ssionThe minimum lot size is generally the amount of material in a single conveyance, such as a truck load, a rail-car load, or a bargeload.At the other extreme, a lot might be defined by a user as and can be the total amount of material used in a single constructionor by a supplier in a production
16、run where manufacturing conditions are unchanged or as the amount of material produced overa given interval of time.3.2.3 sampling unit, namount of material from which a grab sample is taken.3.2.3.1 DiscussionGenerally a lot is subdivided into sampling units, and then sampling units are chosen at ra
17、ndom for taking of grab samples. Thesize of the sampling unit is user-defined, depending on the purposes of the evaluation. The sampling unit is often the amount ofmaterial in a single conveyance to the concrete producer, such as a delivery truck, rail-car, or barge. The term sub lotsublot issometim
18、es used to define this concept.as an alternative for sampling unit.4. Significance and Use4.1 This practice provides a systematic procedure for sampling and determining the variability of user-selected properties ofingredients of concrete. concrete-making materials. Results derived from application
19、of the practice are generally intended forinformation only and are not requirements of any existing ASTM specification on concrete or concreteconcrete-making materials.A concrete materials specification may make reference to this practice as a means of obtaining variability information, but needsto
20、define the properties to be measured and the lot size and sample unit to be used. TheThis practice is applicable to both producersof concrete materials and to and consumers of concreteconcrete-making materials, although details of application of the practicemay vary, depending on the intended purpos
21、e of the user of thethis practice.4.2 The procedure is applicable to any quantitative property of any concrete ingredientconcrete-making material that can bemeasured by a standard test method. The procedure is based on grab samples, which will tend to show the maximum amount ofvariation inof the sel
22、ected material property. being evaluated. The procedure is useful if grab samples are obtained from samplingunits that are being delivered to the user of a material and better represents the variability of the material used in concreteproduction compared with testingthan tests performed on the mater
23、ial for specification compliance. compliance that aredocumented on a mill test report or material certification. The procedure was developed for application to materials from a singlesource, but it can be applied to a materials delivery stream from more than one source, depending on the purposes of
24、the user ofthe practice. Variations among test results on separate samples within a lot are corrected for testing error, therefore giving anestimate of the variability of the selected material property. The variability of the selected material property provides the user withone indicator of the sour
25、ce variation of the concrete ingredient.concrete-making material.4.3 Although variability in properties of concreteconcrete-making materials can be a significant cause of variability in concreteproperties, this practice does not purport to give information on this relationship. This practice does gi
26、ve information on variabilityof ingredients concrete-making materials from which the user can, along with supplementary information or correlative testing ofconcrete properties, develop quantitative estimates of the effects.5. Sampling5.1 The sampling plan underlying the analysis of variability is c
27、ritical to the interpretation of results. The sampling plan willvary, depending on the details of concreteconcrete-making materials supply and user-defined purpose of the evaluation. Thesampling plan should, at a minimum, address the lot size and sampling frequency, location and procedure of samplin
28、g fromsampling unit, and handling of samples. The required sampling frequency depends on how the data are being used and the natureof the material being evaluated. All sampling is to be performed by personnel specifically trained for this purpose. The samplingplan should be described in the report (
29、Section 8).5.2 The first step in determiningdefining the sampling plan is to defineestablish the objective and scope of the evaluation. Thisrequires considerable experience and knowledge of details involved with the particular production under evaluation. The objectiveand scope of the evaluation may
30、 vary between users and producers of materials. It may also range from determining the variabilityof materials during a relatively small production period to covering a very long production period. If there is no prior knowledgeof the variability of a material property, material, or if it is suspect
31、ed that the material might show considerable variation, arelatively intense sampling plan might be designed initially. If prior knowledge indicates that the material property is relativelystable,uniform, then a less intense sampling plan might be designed.5.3 The second step is to define the size of
32、 the lot and the size of the sampling unit (see 3.2). Typically a lot is divided into anumber of sampling units; then sampling units are selected at random for the taking of grab samples. Typically, the number ofsampling units is larger than the number actually sampled, of samples obtained, although
33、 for small lot sizes, the number ofsampling units may equal the number of samples being taken. Alternatively, sampling may be performed on a time-basedfrequency.C1451 1825.4 Take random grab samples from a point in the storage and handling process of the material that will accurately reflect thevari
34、ability of the material as it will be used in concrete. Practice D3665 provides general guidance.Additional guidance for specificmaterials is listed in 5.4.1 5.4.4. Identify samples by the date on which the material was shipped or received, its source, anddesignated type and applicable specification
35、s.5.4.1 Sample cement in accordance with Test Method C917C917/C917M.5.4.2 Sample fine and coarse aggregates in accordance with Practice D75D75/D75M.5.4.3 Sample chemical admixtures in accordance with Specification C494/C494M.5.4.4 Sample pozzolan or slag cement in accordance with Test Method C917C91
36、7/C917M.6. Procedure6.1 Total VariationTest all samples in accordance with the appropriate ASTM Test Method for the particular property beingmeasured. Choose a property that is expected to have a significant influence on concrete performance, and choose a test methodthat has good precision so that t
37、he material variability is not masked by the testing error. It is also advisable to select a methodthat does not incur significant cost and is conducted frequently so the operators are proficient with the procedure. Variation withina single source is estimated by first calculating total variation fr
38、om test data on grab samples, and then correcting this by subtractingvariation inherent in the test method (testing error). Best results are obtained if all tests are conducted in the same laboratory, butguidance is provided if it is necessary to use data from more than one laboratory. Calculate the
39、 total variation among the samples,as directed in 7.1.3. The total variation includes testing error.6.2 Testing ErrorTesting error comprises components due to within-laboratory variation and between-laboratory variation. Ifresults are obtained from only one laboratory, then between-laboratory variat
40、ion makes no contribution. If data are obtained frommore than one laboratory, it is preferable to keep data from each one separate during data analysis, pooling estimates of variationat the end of the analysis.6.2.1 To estimate within-laboratory testing error, duplicate tests made from a single samp
41、le are required. Samples from differentdays Grab samples from separate sampling units must be tested in duplicate until results of at least ten samples have been testedin duplicate. duplicate tests are obtained. The frequency of duplicate tests initially should be at least once in five samples and n
42、otless frequently than once per month. Calculate the testing error standard deviation and the coefficient of variation from duplicatetests conducted in each laboratory, as outlined in 7.1.4.6.2.2 If the testing error exceeds the single laboratoryoperator precision (1s or 1s%) reported in the precisi
43、on statement for theapplicable test method, but is less than 1.5 times this value, continue duplicate tests at this same frequency. If the testing error isequal to or less than the testing error reported in the precision statement, single operator precision, reduce the frequency ofduplicate testing.
44、 If the testing error exceeds 1.5 times the testing error reported in the precision statement, the single operatorprecision, the data are of unacceptable precision, and the laboratory procedure and equipment should be thoroughly examined. Usethe results of duplicate tests, indicating acceptable prec
45、ision, to estimate the within-laboratory testing error for all other types ofsimilar materials tested in that laboratory during the same period of time.6.2.3 When two or more laboratories are used to evaluate the variability of a source, then additional tests of a standard sampleor exchanged portion
46、s of the same sample may be necessary to determine differences in testing that are likely to be obtained inthe different laboratories. When two laboratories exchange portions of the sample and run single tests, results from the laboratoriesshall not differ by more than the multi-laboratory precision
47、 (d2s or d2s% value). If a larger number of samples are exchanged, thenthe difference between laboratories should not exceed the d2s or d2s% more than 5 % of the time.6.3 Single-Source VariationCalculate single-source variation according to 7.1.5.7. Calculation7.1 The calculations shall include the
48、following:NOTE 1Standard deviation can be calculated by other methods that are available in MNL 7.3 Electronic calculators and spreadsheets are availablefor obtaining the average and sample standard deviation directly after entering the test results.7.1.1 Average of All Test ResultsCalculate the ave
49、rage of all test results during the report period using Eq 1. Use only the firsttest result from each sample that is tested in duplicate.x 5x1 1x2 11xnn (1)where:x = average of all test results,x1, x2, . xn = individual determinations, andn = number of individual determinations.3 Manual on Presentation of Data and Control Chart Analysis, MNL7, Committee E11 on Statistical Control, ASTM International, 2010, www.astm.org.C1451 1837.1.2 Moving AverageAfter five test results are obtained, begin to calculate the moving average of the five most recent resultsusing E
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