ASTM C172 C172M-2010 Standard Practice for Sampling Freshly Mixed Concrete《新鲜预拌混凝土取样的标准实施规程》.pdf

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1、Designation: C172/C172M 10Standard Practice forSampling Freshly Mixed Concrete1This standard is issued under the fixed designation C172/C172M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the year of last revision. A number in p

2、arentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope*1.1 This practice covers procedures for obtaining represen-tative sa

3、mples of fresh concrete as delivered to the project siteon which tests are to be performed to determine compliancewith quality requirements of the specifications under which theconcrete is furnished (Note 1). The practice includes samplingfrom stationary, paving and truck mixers, and from agitatinga

4、nd nonagitating equipment used to transport central-mixedconcrete.1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combi

5、ningvalues from the two systems may result in non-conformancewith the standard.NOTE 1Composite samples are required by this practice, unlessspecifically excepted by procedures governing the tests to be performedsuch as tests to determine uniformity of consistency and mixer efficiency.Procedures used

6、 to select the specific test batches are not described in thispractice, but it is recommended that random sampling be used todetermine overall specification compliance.1.3 This practice also covers the procedures to be used forpreparing a sample of concrete for further testing where it isdesirable o

7、r necessary to remove the aggregate larger than adesignated size. This removal of larger aggregate particles ispreferably accomplished by wet-sieving.1.4 The text of this standard references notes and footnoteswhich provide explanatory material and shall not be consideredas requirements of the pract

8、ice.1.5 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. (WarningFr

9、eshhydraulic cementitious mixtures are caustic and may causechemical burns to skin and tissue upon prolonged exposure.2)2. Referenced Documents2.1 ASTM Standards:3E11 Specification for Woven Wire Test Sieve Cloth and TestSieves3. Significance and Use3.1 This practice is intended to provide standard

10、require-ments and procedures for sampling freshly mixed concretefrom different containers used in the production or transporta-tion of concrete. The detailed requirements as to materials,mixtures, air content, temperature, number of specimens,slump, interpretation of results, and precision and bias

11、are inspecific test methods.4. Sampling4.1 The elapsed time shall not exceed 15 min. betweenobtaining the first and final portions of the composite sample.4.1.1 Transport the individual samples to the place wherefresh concrete tests are to be performed or where test speci-mens are to be molded. They

12、 shall be combined and remixedwith a shovel the minimum amount necessary to ensureuniformity and compliance with the maximum time limitsspecified in 4.1.2.4.1.2 Start tests for slump, temperature, and air contentwithin 5 min after obtaining the final portion of the compositesample. Complete these te

13、sts expeditiously. Start moldingspecimens for strength tests within 15 min after fabricating thecomposite sample. Expeditiously obtain and use the sampleand protect the sample from the sun, wind, and other sources ofrapid evaporation, and from contamination.1This practice is under the jurisdiction o

14、f ASTM Committee C09 on Concreteand ConcreteAggregates and is the direct responsibility of Subcommittee C09.60 onTesting Fresh Concrete.Current edition approved Oct. 1, 2010. Published November 2010. Originallyapproved in 1942. Last previous edition approved in 2008 as C17208 DOI:10.1520/C0172_C0172

15、M-10.2Section on Safety Precautions, Manual of Aggregate and Concrete Testing,Annual Book of ASTM Standards, Vol 04.02.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer

16、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.5. Procedure5.1 Size of SampleMake the samples to be used for

17、strength tests a minimum of 28 L 1 ft3. Smaller samples arenot prohibited for routine air content, temperature, and slumptests. The size of the samples shall be dictated by the maximumaggregate size.5.2 The procedures used in sampling shall include the use ofevery precaution that will assist in obta

18、ining samples that aretruly representative of the nature and condition of concretesampled as follows:NOTE 2Sampling should normally be performed as the concrete isdelivered from the mixer to the conveying vehicle used to transport theconcrete to the forms; however, specifications may require other p

19、oints ofsampling, such as the discharge of a concrete pump.5.2.1 Sampling from Stationary Mixers, Except PavingMixersSample the concrete by collecting two or moreportions taken at regularly spaced intervals during discharge ofthe middle portion of the batch. Obtain these portions withinthe time limi

20、t specified in Section 4. Combine into onecomposite sample for testing purposes. Do not obtain portionsof the composite sample from the very first or last part of thebatch discharge (Note 3). Perform sampling by passing areceptacle completely through the discharge stream, or bycompletely diverting t

21、he discharge into a sample container. Ifdischarge of the concrete is too rapid to divert the completedischarge stream, discharge the concrete into a container ortransportation unit sufficiently large to accommodate the entirebatch and then accomplish the sampling in the same manner asgiven above. Ta

22、ke care not to restrict the flow of concrete fromthe mixer, container, or transportation unit so as to causesegregation. These requirements apply to both tilting andnontilting mixers.NOTE 3No samples should be taken before 10 % or after 90 % of thebatch has been discharged. Due to the difficulty of

23、determining the actualquantity of concrete discharged, the intent is to provide samples that arerepresentative of widely separated portions, but not the beginning and theend of the load.5.2.2 Sampling from Paving MixersSample the concreteafter the contents of the paving mixer have been discharged.Ob

24、tain samples from at least five different portions of the pileand combine them into one composite sample for test purposes.Avoid contamination with subgrade material or prolongedcontact with and absorptive subgrade. To preclude contamina-tion or absorption by the subgrade, sample the concrete byplac

25、ing three shallow containers on the subgrade and discharg-ing the concrete across the container. Combine the samples soobtained into one composite sample for test purposes. Thecontainers shall be of a size sufficient to provide a compositesample size that is in agreement with the maximum aggregatesi

26、ze.NOTE 4In some instances, the containers may have to be supportedabove the subgrade to prevent displacement during discharge.5.2.3 Sampling from Revolving Drum Truck Mixers orAgitatorsSample the concrete by collecting two or moreportions taken at regularly spaced intervals during discharge ofthe m

27、iddle portion of the batch. Take the samples so obtainedwithin the time limit specified in Section 4 and combine theminto one composite sample for test purposes. In any case do notobtain samples until after all of the water and any admixtureshave been added to the mixer; also do not obtain samples f

28、romthe very first or last portions of the batch discharge (Note 3).Sample by repeatedly passing a receptacle through the entiredischarge stream or by completely diverting the discharge intoa sample container. Regulate the rate of discharge of the batchby the rate of revolution of the drum and not by

29、 the size of thegate opening.5.2.4 Sampling from Open-Top Truck Mixers, Agitators,Nonagitating Equipment, or Other Types of Open-TopContainersTake samples by whichever of the proceduresdescribed in 5.2.1, 5.2.2,or5.2.3 is most applicable under thegiven conditions.6. Additional Procedure for Large Ma

30、ximum SizeAggregate Concrete6.1 When the concrete contains aggregate larger than thatappropriate for the size of the molds or equipment to be used,wet-sieve the sample as described below except performdensity (unit weight) tests for use in yield computations on thefull mix.NOTE 5The effect of wet-si

31、eving on the test results should beconsidered. For example, wet-sieving concrete causes the loss of a smallamount of air due to additional handling. The air content of the wet-sievedfraction of concrete is greater than that of the total concrete because thelarger size aggregate which is removed does

32、 not contain air. The apparentstrength of wet-sieved concrete in smaller specimens is usually greaterthan that of the total concrete in larger appropriate size specimens. Theeffect of these differences may need to be considered or determined bysupplementary testing for quality control or test result

33、 evaluation pur-poses.6.2 Definition:6.2.1 wet-sieving concretethe process of removing aggre-gate larger than a designated size from the fresh concrete bysieving it on a sieve of the designated size.6.3 Apparatus:6.3.1 Sieves, as designated, conforming to SpecificationE11.6.3.2 ReceptacleA container

34、 of suitable size having anonabsorbent surface.6.3.3 Wet-Sieving EquipmentEquipment for wet-sievingconcrete shall be a sieve as noted in 6.3.1 of suitable size andconveniently arranged and supported so that one can shake itrapidly by either hand or mechanical means. Generally, ahorizontal back and f

35、orth motion is preferred. The equipmentshall be capable of rapidly and effectively removing thedesignated size of aggregate.6.3.4 Hand ToolsShovels, hand scoops, plastering trow-els, and rubber gloves as required.6.4 Procedure:6.4.1 Wet-SievingAfter sampling the concrete, pass theconcrete over the d

36、esignated sieve and remove and discard theaggregate retained. This shall be done before remixing. Shakeor vibrate the sieve by hand or mechanical means until noundersize material remains on the sieve. Mortar adhering to theaggregate retained on the sieve shall not be wiped from itbefore it is discar

37、ded. Place only enough concrete on the sieveat any one time so that after sieving, the thickness of the layerC172/C172M 102of retained aggregate is not more than one particle thick. Theconcrete which passes the sieve shall fall into a batch pan ofsuitable size which has been dampened before use or o

38、nto aclean, moist, nonabsorbent surface. Scrape any mortar adher-ing to the sides of the wet-sieving equipment into the batch.After removing the larger aggregate particles by wet-sievingremix the batch with a shovel the minimum amount necessaryto ensure uniformity and proceed testing immediately.7.

39、Keywords7.1 air content; batch; composite sample; concrete; slump;temperature; wet-sievingSUMMARY OF CHANGESCommittee C09 has identified the location of selected changes to this practice since the last issue, C17208,that may impact the use of this practice. (Approved October 1, 2010)(1) Revised the

40、standard as a dual units practice.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risko

41、f infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this

42、standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake yo

43、ur views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).C172/C172M 103