ASTM C172 C172M-2014 Standard Practice for Sampling Freshly Mixed Concrete《新拌混凝土取样的标准操作规程》.pdf

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1、Designation: C172/C172M 14Standard 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.1. Scope*1.1 This practice covers procedures for obtaining represen-tative samples of fresh concrete as delivered to the project siteon which tests are to be

3、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 agitatingand nonagitating equipment used to transport central-mixedconcrete and from contin

4、uous mixing equipment as describedin Specification C685/C685M.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. Combining

5、values 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 to

6、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 or ne

7、cessary 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 practice.

8、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. (WarningFreshh

9、ydraulic 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 TestSievesC685/C685M Specification for Concrete Made by Volumet-ric Batching and Contin

10、uous Mixing3. Significance and Use3.1 This practice is intended to provide standard 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, temper

11、ature, number of specimens,slump, interpretation of results, and precision and bias 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 wherefres

12、h concrete tests are to be performed or where test speci-mens are to be molded. They 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 contentwith

13、in 5 min after obtaining the final portion of the compositesample. Complete these tests 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 of

14、rapid evaporation, and from contamination.1This practice is under the jurisdiction of ASTM Committee C09 on Concreteand ConcreteAggregates and is the direct responsibility of Subcommittee C09.60 onTesting Fresh Concrete.Current edition approved Feb. 1, 2014. Published February 2014. Originallyapprov

15、ed in 1942. Last previous edition approved in 2010 as C17210. DOI:10.1520/C0172_C0172M-14.2Section 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 Se

16、rvice at serviceastm.org. For Annual Book of ASTMStandards 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 1942

17、8-2959. United States15. Procedure5.1 Size of SampleMake the samples to be used forstrength 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

18、 used in sampling shall include the use ofevery precaution that will assist in obtaining 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

19、 to transport theconcrete to the forms; however, specifications may require other points 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 dis

20、charge ofthe middle portion of the batch. Obtain these portions withinthe time limit 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 passi

21、ng areceptacle completely through the discharge stream, or bycompletely diverting the 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 th

22、e entirebatch and then accomplish the sampling in the same manner asgiven above. Take 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 b

23、efore 10 % or after 90 % of thebatch has been discharged. Due to the difficulty of 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 Mixe

24、rsSample the concreteafter the contents of the paving mixer have been discharged.Obtain 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. T

25、o preclude contamina-tion or absorption by the subgrade, sample the concrete byplacing 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

26、to provide a compositesample size that is in agreement with the maximum aggregatesize.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 collecti

27、ng two or moreportions taken at regularly spaced intervals during discharge ofthe middle 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

28、 water and any admixtureshave been added to the mixer; also do not obtain samples fromthe 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

29、 the rate of discharge of the batchby the rate of revolution of the drum and not by the size of thegate opening.5.2.4 Sampling from Continuous MixersSample the con-crete after the mixture has achieved uniformity of color andtexture following all mix proportioning adjustments. Samplethe concrete at t

30、he frequency specified by collecting two ormore portions taken at regularly spaced intervals duringdischarge of the concrete. Take the portions so obtained withinthe time limit specified in Section 4, and combine them intoone composite sample for test purposes. Do not obtain samplesfrom the very fir

31、st or last portions of a mixers continuousdischarge (Note 3). Sample by repeatedly passing a receptaclethrough the entire discharge stream or by completely divertingthe discharge into a sample container. After obtaining thecomposite sample, wait a minimum of 2 minutes and amaximum of 5 minutes befor

32、e beginning tests (Note 5).NOTE 5The waiting period prior to commencing the testing is neededbecause the mix water is input only seconds before discharge from thecontinuous mixer.5.2.5 Sampling from Open-Top Truck Mixers, Agitators,Nonagitating Equipment, or Other Types of Open-TopContainersTake sam

33、ples 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 Maximum SizeAggregate Concrete6.1 When the concrete contains aggregate larger than thatappropriate for the size of the molds or equipment to be used,wet

34、-sieve the sample as described below except performdensity (unit weight) tests for use in yield computations on thefull mix.NOTE 6The effect of wet-sieving on the test results should beconsidered. For example, wet-sieving concrete causes the loss of a smallamount of air due to additional handling. T

35、he air content of the wet-sievedfraction of concrete is greater than that of the total concrete because thelarger size aggregate which is removed does not contain air. The apparentstrength of wet-sieved concrete in smaller specimens is usually greaterthan that of the total concrete in larger appropr

36、iate size specimens. Theeffect of these differences may need to be considered or determined bysupplementary testing for quality control or test result 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 concret

37、e 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 of suitable size having anonabsorbent surface.C172/C172M 1426.3.3 Wet-Sieving EquipmentEquipment for wet-sievingconcrete shall be a sieve as noted in

38、 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 forth motion is preferred. The equipmentshall be capable of rapidly and effectively removing thedesignated size of aggregate.6.3.4 Hand T

39、oolsShovels, hand scoops, plasteringtrowels, and rubber gloves as required.6.4 Procedure:6.4.1 Wet-SievingAfter sampling the concrete, pass theconcrete over the designated sieve and remove and discard theaggregate retained. This shall be done before remixing. Shakeor vibrate the sieve by hand or mec

40、hanical means until noundersize material remains on the sieve. Mortar adhering to theaggregate retained on the sieve shall not be wiped from itbefore it is discarded. Place only enough concrete on the sieveat any one time so that after sieving, the thickness of the layerof retained aggregate is not

41、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 onto aclean, moist, nonabsorbent surface. Scrape any mortar adher-ing to the sides of the wet-sieving equipment into the batch.After removing the larger

42、aggregate particles by wet-sievingremix the batch with a shovel the minimum amount necessaryto ensure uniformity and proceed testing immediately.7. Keywords7.1 air content; batch; composite sample; concrete; slump;temperature; wet-sievingSUMMARY OF CHANGESCommittee C09 has identified the location of

43、 selected changes to this practice since the last issue, C17210,that may impact the use of this practice. (Approved February 1, 2014)(1) Added new Section 5.2.4 and renumbered accordingly.ASTM International takes no position respecting the validity of any patent rights asserted in connection with an

44、y item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical

45、 committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration a

46、t a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor

47、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 143