ASTM C172 C172M-2014a Standard Practice for Sampling Freshly Mixed Concrete《新搅拌混凝土取样的标准实施规程》.pdf

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1、Designation: C172/C172M 14C172/C172M 14aStandard 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.

2、 A number in parentheses 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 representative samples of fresh concrete as delivered to the project site onwhich tes

3、ts are to be performed to determine compliance with quality requirements of the specifications under which the concreteis furnished (Note 1). The practice includes sampling from stationary, paving and truck mixers, and from agitating and nonagitatingequipment used to transport central-mixed concrete

4、 and from continuous mixing equipment as described in SpecificationC685/C685M.1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in eachsystem may not be exact equivalents; therefore, each system shall be used independently of th

5、e other. Combining values from thetwo systems may result in non-conformance with the standard.NOTE 1Composite samples are required by this practice, unless specifically excepted by procedures governing the tests to be performed such as teststo determine uniformity of consistency and mixer efficiency

6、. Procedures used to select the specific test batches are not described in this practice, but itis recommended that random sampling be used to determine overall specification compliance.1.3 This practice also covers the procedures to be used for preparing a sample of concrete for further testing whe

7、re it is desirableor necessary to remove the aggregate larger than a designated size. This removal of larger aggregate particles is preferablyaccomplished by wet-sieving.1.4 The text of this standard references notes and footnotes which provide explanatory material and shall not be considered asrequ

8、irements of the practice.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior

9、 to use. (WarningFresh hydraulic cementitious mixtures are caustic and may cause chemical burns to skin andtissue upon prolonged exposure.2)2. Referenced Documents2.1 ASTM Standards:3E11 Specification for Woven Wire Test Sieve Cloth and Test SievesC685/C685M Specification for Concrete Made by Volume

10、tric Batching and Continuous Mixing3. Significance and Use3.1 This practice is intended to provide standard requirements and procedures for sampling freshly mixed concrete fromdifferent containers used in the production or transportation of concrete. The detailed requirements as to materials, mixtur

11、es, aircontent, temperature, number of specimens, slump, interpretation of results, and precision and bias are in specific test methods.4. Sampling4.1 The elapsed time shall not exceed 15 min. between obtaining the first and final portions of the composite sample.1 This practice is under the jurisdi

12、ction ofASTM Committee C09 on Concrete and ConcreteAggregates and is the direct responsibility of Subcommittee C09.60 on TestingFresh Concrete.Current edition approved Feb. 1, 2014Oct. 1, 2014. Published February 2014November 2014. Originally approved in 1942. Last previous edition approved in 20102

13、014as C17210.14. DOI: 10.1520/C0172_C0172M-14.10.1520/C0172_C0172M-14A.2 Section on Safety Precautions, Manual of Aggregate and Concrete Testing, Annual Book of ASTM Standards, Vol 04.02.3 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceas

14、tm.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 standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becau

15、seit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appear

16、s at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14.1.1 Transport the individual samples to the place where fresh concrete tests are to be performed or where test specimens areto be molded. They shall be com

17、bined and remixed with a shovel the minimum amount necessary to ensure uniformity andcompliance with the maximum time limits specified in 4.1.2.4.1.2 Start tests for slump, temperature, and air content within 5 min after obtaining the final portion of the composite sample.Complete these tests expedi

18、tiously. Start molding specimens for strength tests within 15 min after fabricating the compositesample. Expeditiously obtain and use the sample and protect the sample from the sun, wind, and other sources of rapid evaporation,and from contamination.5. Procedure5.1 Size of SampleMake the samples to

19、be used for strength tests a minimum of 28 L 1 ft3. Smaller samples are notprohibited for routine air content, temperature, and slump tests. The size of the samples shall be dictated by the maximumaggregate size.5.2 The procedures used in sampling shall include the use of every precaution that will

20、assist in obtaining samples that are trulyrepresentative of the nature and condition of concrete sampled as follows:NOTE 2Sampling should normally be performed as the concrete is delivered from the mixer to the conveying vehicle used to transport the concreteto the forms; however, specifications may

21、 require other points of sampling, such as the discharge of a concrete pump.5.2.1 Sampling from Stationary Mixers, Except Paving MixersSample the concrete by collecting two or more portions takenat regularly spaced intervals during discharge of the middle portion of the batch. Obtain these portions

22、within the time limitspecified in Section 4. Combine into one composite sample for testing purposes. Do not obtain portions of the composite samplefrom the very first or last part of the batch discharge (Note 3). Perform sampling by passing a receptacle completely through thedischarge stream, or by

23、completely diverting the discharge into a sample container. If discharge of the concrete is too rapid to divertthe complete discharge stream, discharge the concrete into a container or transportation unit sufficiently large to accommodate theentire batch and then accomplish the sampling in the same

24、manner as given above. Take care not to restrict the flow of concretefrom the mixer, container, or transportation unit so as to cause segregation. These requirements apply to both tilting and nontiltingmixers.NOTE 3No samples should be taken before 10 % or after 90 % of the batch has been discharged

25、. Due to the difficulty of determining the actualquantity of concrete discharged, the intent is to provide samples that are representative of widely separated portions, but not the beginning and the endof the load.5.2.2 Sampling from Paving MixersSample the concrete after the contents of the paving

26、mixer have been discharged. Obtainsamples from at least five different portions of the pile and combine them into one composite sample for test purposes. Avoidcontamination with subgrade material or prolonged contact with and absorptive subgrade. To preclude contamination or absorptionby the subgrad

27、e, sample the concrete by placing three shallow containers on the subgrade and discharging the concrete across thecontainer. Combine the samples so obtained into one composite sample for test purposes. The containers shall be of a size sufficientto provide a composite sample size that is in agreemen

28、t with the maximum aggregate size.NOTE 4In some instances, the containers may have to be supported above the subgrade to prevent displacement during discharge.5.2.3 Sampling from Revolving Drum Truck Mixers or AgitatorsSample the concrete by collecting two or more portions takenat regularly spaced i

29、ntervals during discharge of the middle portion of the batch. Take the samples so obtained within the time limitspecified in Section 4 and combine them into one composite sample for test purposes. In any case do not obtain samples until afterall of the water and any admixtures have been added to the

30、 mixer; also do not obtain samples from the very first or last portionsof the batch discharge (Note 3). Sample by repeatedly passing a receptacle through the entire discharge stream or by completelydiverting the discharge into a sample container. Regulate the rate of discharge of the batch by the ra

31、te of revolution of the drumand not by the size of the gate opening.5.2.4 Sampling from Continuous MixersSample the concrete after the mixture has achieved uniformity of color and texturedischarge of at least 140 L 5 ft3 of concrete, following all mixmixture proportioning adjustments. Sample the con

32、crete at thefrequency specified by collecting two or more portions taken at regularly spaced intervals during discharge of the concrete. Takethe portions so obtained within the time limit specified in Section 4, and combine them into one composite sample for test purposes.Do not obtain samples from

33、the very first or last portions of a mixers continuous discharge (Note 3). Sample by repeatedly passinga receptacle through the entire discharge stream or by completely diverting the discharge into a sample container. After obtainingthe composite sample, wait a minimum of 2 minutes and a maximum of

34、5 minutes before beginning tests (Note 5).NOTE 5The waiting period prior to commencing the testing is needed because 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-Top

35、ContainersTake samples by whichever of the procedures described in 5.2.1, 5.2.2, or 5.2.3 is most applicable under the given conditions.6. Additional Procedure for Large Maximum Size Aggregate Concrete6.1 When the concrete contains aggregate larger than that appropriate for the size of the molds or

36、equipment to be used,wet-sieve the sample as described below except perform density (unit weight) tests for use in yield computations on the full mix.C172/C172M 14a2NOTE 6The effect of wet-sieving on the test results should be considered. For example, wet-sieving concrete causes the loss of a small

37、amount ofair due to additional handling. The air content of the wet-sieved fraction of concrete is greater than that of the total concrete because the larger sizeaggregate which is removed does not contain air. The apparent strength of wet-sieved concrete in smaller specimens is usually greater than

38、 that of thetotal concrete in larger appropriate size specimens. The effect of these differences may need to be considered or determined by supplementary testing forquality control or test result evaluation purposes.6.2 Definition:6.2.1 wet-sieving concretethe process of removing aggregate larger th

39、an a designated size from the fresh concrete by sievingit on a sieve of the designated size.6.3 Apparatus:6.3.1 Sieves, as designated, conforming to Specification E11.6.3.2 ReceptacleA container of suitable size having a nonabsorbent surface.6.3.3 Wet-Sieving EquipmentEquipment for wet-sieving concr

40、ete shall be a sieve as noted in 6.3.1 of suitable size andconveniently arranged and supported so that one can shake it rapidly by either hand or mechanical means. Generally, a horizontalback and forth motion is preferred. The equipment shall be capable of rapidly and effectively removing the design

41、ated size ofaggregate.6.3.4 Hand ToolsShovels, hand scoops, plastering trowels, and rubber gloves as required.6.4 Procedure:6.4.1 Wet-SievingAfter sampling the concrete, pass the concrete over the designated sieve and remove and discard theaggregate retained. This shall be done before remixing. Shak

42、e or vibrate the sieve by hand or mechanical means until no undersizematerial remains on the sieve. Mortar adhering to the aggregate retained on the sieve shall not be wiped from it before it isdiscarded. Place only enough concrete on the sieve at any one time so that after sieving, the thickness of

43、 the layer of retainedaggregate is not more than one particle thick. The concrete which passes the sieve shall fall into a batch pan of suitable size whichhas been dampened before use or onto a clean, moist, nonabsorbent surface. Scrape any mortar adhering to the sides of thewet-sieving equipment in

44、to the batch. After removing the larger aggregate particles by wet-sieving remix the batch with a shovelthe minimum amount necessary to ensure uniformity and proceed testing immediately.7. Keywords7.1 air content; batch; composite sample; concrete; slump; temperature; wet-sievingSUMMARY OF CHANGESCo

45、mmittee C09 has identified the location of selected changes to this practice since the last issue,C17210,14, that may impact the use of this practice. (Approved FebruaryOctober 1, 2014)(1) Added new Section 5.2.4 and renumbered accordingly.(1) Revised first sentence of 5.2.4.ASTM International takes

46、 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 riskof infringement of such rights, are entirely their own resp

47、onsibility.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 standard or for additional standardsand should be addressed

48、 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 your views known to the ASTM Committee on Standards, at the a

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