1、Designation: C1451 11Standard Practice forDetermining Variability of Ingredients of Concrete From aSingle Source1This standard is issued under the fixed designation C1451; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、 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 thevariability of properties of concrete materials from a singlesou
3、rce. 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 are presented only asillustrations of calculation methods that are applicable inde-pendent of the system of units.1.
4、3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Doc
5、uments2.1 ASTM Standards:2C109/C109M Test Method for Compressive Strength ofHydraulic Cement Mortars (Using 2-in. or 50-mm CubeSpecimens)C125 Terminology Relating to Concrete and Concrete Ag-gregatesC219 Terminology Relating to Hydraulic CementC494/C494M Specification for Chemical Admixtures forConc
6、reteC917 Test Method for Evaluation of Cement StrengthUniformity From a Single SourceD75 Practice for Sampling AggregatesD3665 Practice for Random Sampling of Construction Ma-terials3. Terminology3.1 Definitions:3.1.1 For definitions of terms relating to this practice refer toTerminology C125 and Te
7、rminology C219.3.2 Definitions of Terms Specific to This Standard:3.2.1 grab sample, na specified quantity of materialobtained in a single operation from a sampling unit.3.2.1.1 DiscussionThe goal of procuring a grab sample isto obtain a small portion of material that is characteristic of thatin the
8、 sampling unit.3.2.2 lot, na user-defined quantity, typically representingany amount of material for which variability information is tobe calculated.3.2.2.1 DiscussionThe minimum lot size is generally theamount of material in a single conveyance, such as a truckload, a rail-car load, or a barge loa
9、d. At the other extreme, a lotmight be defined by a user as the total amount of material usedin a single construction or by a supplier as the amount ofmaterial produced over a given interval of time.3.2.3 sampling unit, namount of material from which agrab sample is taken.3.2.3.1 DiscussionGenerally
10、 a lot is subdivided into sam-pling units, and then sampling units are chosen at random fortaking of grab samples. The size of the sampling unit isuser-defined, depending on the purposes of the evaluation. Theterm sub lot is sometimes used to define this concept.4. Significance and Use4.1 This pract
11、ice provides a systematic procedure for sam-pling and determining the variability of user-selected proper-ties of ingredients of concrete. Results derived from applica-tion of the practice are generally intended for information onlyand are not requirements of any existing ASTM specificationon concre
12、te or concrete materials. A concrete materials speci-fication may make reference to this practice as a means ofobtaining variability information, but needs to define theproperties to be measured and the lot size and sample unit to beused. The practice is applicable to both producers of concretemater
13、ials and to consumers of concrete materials, althoughdetails of application of the practice may vary, depending onthe intended purpose of the user of the practice.4.2 The procedure is applicable to any quantitative propertyof any concrete ingredient that can be measured by a standardtest method. The
14、 procedure is based on grab samples, whichwill tend to show the maximum amount of variation in the1This practice is under the jurisdiction of ASTM Committee C09 on Concreteand ConcreteAggregates and is the direct responsibility of Subcommittee C09.94 onEvaluation of Data (Joint C09 and C01).Current
15、edition approved July 1, 2011. Published August 2011. Originallyapproved in 1999. Last previous edition approved in 2005 as C145105. DOI:10.1520/C1451-11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMS
16、tandards volume information, refer to the standards Document Summary page onthe ASTM website.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.selected material property
17、. The procedure is useful if grabsamples are obtained from sampling units that are beingdelivered to the user of a material and better represents thevariability of the material used in concrete production com-pared with testing on the material for specification compliance.The procedure was developed
18、 for application to materials froma single source, but it can be applied to a materials deliverystream from more than one source, depending on the purposesof the user of the practice. Variations among test results arecorrected for testing error, therefore giving an estimate of thevariability of the
19、selected material property. The variability ofthe selected material property provides the user with oneindicator of the source variation of the concrete ingredient.4.3 Although variability in properties of concrete materialscan be a significant cause of variability in concrete properties,this practi
20、ce does not purport to give information on thisrelationship. This practice does give information on variabilityof ingredients from which the user can, along with supplemen-tary information or correlative testing of concrete properties,develop quantitative estimates of the effects.5. Sampling5.1 The
21、sampling plan underlying the analysis of variabilityis critical to the interpretation of results. The sampling plan willvary, depending on the details of concrete materials supply anduser-defined purpose of the evaluation. The sampling planshould, at a minimum, address the lot size and samplingfrequ
22、ency, location and procedure of sampling from samplingunit, and handling of samples. The required sampling fre-quency depends on how the data are being used and the natureof the material being evaluated. All sampling is to be per-formed by personnel specifically trained for this purpose. Thesampling
23、 plan should be described in the report (Section 8).5.2 The first step in determining the sampling plan is todefine the objective and scope of the evaluation. This requiresconsiderable experience and knowledge of details involvedwith the particular production under evaluation. The objectiveand scope
24、 of the evaluation may vary between users andproducers of materials. It may also range from determining thevariability of materials during a relatively small productionperiod to covering a very long production period. If there is noprior knowledge of the variability of a material property, or ifit i
25、s suspected that the material might show considerablevariation, a relatively intense sampling plan might be designedinitially. If prior knowledge indicates that the material propertyis relatively stable, then a less intense sampling plan might bedesigned.5.3 The second step is to define the size of
26、the lot and thesize of the sampling unit (see 3.2). Typically a lot is dividedinto a number of sampling units; then sampling units areselected at random for the taking of grab samples. Typically,the number of sampling units is larger than the number actuallysampled, although for small lot sizes, the
27、 number of samplingunits may equal the number of samples being taken. Alterna-tively, sampling may be performed on a time-based frequency.5.4 Take random grab samples from a point in the storageand handling process of the material that will accurately reflectthe variability of the material as it wil
28、l be used in concrete.Practice D3665 provides general guidance. Additional guid-ance for specific materials is listed in 5.4.1-5.4.4. Identifysamples by the date on which the material was shipped orreceived, its source, and designated type and applicable speci-fications.5.4.1 Sample cement in accord
29、ance with Test Method C917.5.4.2 Sample fine and coarse aggregates in accordance withPractice D75.5.4.3 Sample chemical admixtures in accordance withSpecification C494/C494M.5.4.4 Sample pozzolan or slag cement in accordance withTest Method C917.6. Procedure6.1 Total VariationTest all samples in acc
30、ordance with theappropriate ASTM Test Method for the particular propertybeing measured. Choose a property that is expected to have asignificant influence on concrete performance, and choose atest method that has good precision so that the materialvariability is not masked by the testing error. It is
31、 alsoadvisable to select a method that does not incur significant costand is conducted frequently so the operators are proficient withthe procedure. Variation within a single source is estimated byfirst calculating total variation from test data on grab samples,and then correcting this by subtractin
32、g variation inherent in thetest method (testing error). Best results are obtained if all testsare conducted in the same laboratory, but guidance is providedif it is necessary to use data from more than one laboratory.Calculate the total variation among the samples, as directed in7.1.3. The total var
33、iation includes testing error.6.2 Testing ErrorTesting error comprises components dueto within-laboratory variation and between-laboratory varia-tion. If results are obtained from only one laboratory, thenbetween-laboratory variation makes no contribution. If data areobtained from more than one labo
34、ratory, it is preferable to keepdata from each one separate during data analysis, poolingestimates of variation at the end of the analysis.6.2.1 To estimate within-laboratory testing error, duplicatetests made from a single sample are required. Samples fromdifferent days must be tested in duplicate
35、until at least tensamples have been tested in duplicate. The frequency ofduplicate tests initially should be at least once in five samplesand not less frequently than once per month. Calculate thetesting error standard deviation and the coefficient of variationfrom duplicate tests conducted in each
36、laboratory, as outlinedin 7.1.4.6.2.2 If the testing error exceeds the single laboratoryprecision (1s or 1s%) reported in the precision statement for theapplicable test method, but is less than 1.5 times this value,continue duplicate tests at this same frequency. If the testingerror is equal to or l
37、ess than the testing error reported in theprecision statement, reduce the frequency of duplicate testing.If the testing error exceeds 1.5 times the testing error reportedin the precision statement, the data are of unacceptableprecision, and the laboratory procedure and equipment shouldbe thoroughly
38、examined. Use the results of duplicate tests,indicating acceptable precision, to estimate the within-laboratory testing error for all other types of similar materialstested in that laboratory during the same period of time.C1451 1126.2.3 When two or more laboratories are used to evaluatethe variabil
39、ity of a source, then additional tests of a standardsample or exchanged portions of the same sample may benecessary to determine differences in testing that are likely tobe obtained in the different laboratories. When two laboratoriesexchange portions of the sample and run single tests, resultsfrom
40、the laboratories shall not differ by more than the multi-laboratory precision (d2s or d2s% value). If a larger number ofsamples are exchanged, then the difference between laborato-ries should not exceed the d2s or d2s% more than 5 % of thetime.6.3 Single-Source VariationCalculate single-source varia
41、-tion according to 7.1.5.7. Calculation7.1 The calculations shall include the following:NOTE 1Standard deviation can be calculated by other methods thatare available in MNL 7.3Electronic calculators and spreadsheets areavailable for obtaining the average and sample standard deviation directlyafter e
42、ntering the test results.7.1.1 Average of All Test ResultsCalculate the average ofall test results during the report period using Eq 1. Use only thefirst test result from each sample that is tested in duplicate.x 5x11 x21 . 1 xnn(1)where:x = average of all test results,x1,x2, . xn= individual determ
43、inations, andn = number of individual determinations.7.1.2 Moving AverageAfter five test results are obtained,begin to calculate the moving average of the five most recentresults using Eq 2. Update the moving average by adding themost recent test result and deleting the oldest previous testresult.x5
44、5xi41 xi31 xi21 xi11 xi5(2)where:x5= moving average of five consecutive test results, andxi= the most recent of five consecutive test results.7.1.3 Total Standard Deviation:st5x1 x!21 x2 x!21 . 1 xn x!2n 1!(3)where:st= total standard deviation in units of measurement.7.1.4 Testing Error:7.1.4.1 The
45、standard deviation for testing error is calculatedas follows (See Note 2):se5(d22k(4)where:se= standard deviation for testing error estimated fromtests of duplicate determinations made in a singlelaboratory from different samples,d = difference between duplicate determinations for eachsample, andk =
46、 number of sets of duplicate determinations.NOTE 2Table 1 is an example of test results obtained from duplicatetests on 10 samples.7.1.4.2 If the precision of the test method is stated in termsof a coefficient of variation, calculate the coefficient of varia-tion for testing error as follows:CVe5sex
47、d(5)where:CVe= coefficient of variation for testing error estimatedfrom duplicate determinations made in a singlelaboratory, andxd= overall average of duplicate determinations.7.1.5 Single-Source Variation:7.1.5.1 Variation of material from a single source expressedin terms of standard deviation, co
48、rrected for testing error, iscalculated as follows:sc5 =st2 se2(6)where:sc= single source standard deviation corrected for testingerror.7.1.5.2 Single-source variation expressed as coefficient ofvariation (CV), corrected for testing error, is calculated asfollows:CVc5scx(7)7.1.5.3 If data are collec
49、ted from two laboratories, calculatethe single source variation for each laboratory using Eq 6.Calculate the pooled single-source standard deviation as fol-lows:sc5n11!sc121 n21!sc22n11 n22(8)where:sc= pooled estimate of single-source standarddeviationsc1and sc2= standard deviation corrected for testing errorfrom labratory 1 and labratory 2, respec-tively, andn1and n2= number of tests in laboratory 1 and labora-tory 2, respectively.8. Report8.1 Provide information to identify the material sampledincluding the following:8.1.1 Name of man
