1、Designation: C31/C31M 18Standard Practice forMaking and Curing Concrete Test Specimens in the Field1This standard is issued under the fixed designation C31/C31M; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revi
2、sion. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope*1.1 This practice covers procedures for maki
3、ng and curingcylinder and beam specimens from representative samples offresh concrete for a construction project.1.2 The concrete used to make the molded specimens shallbe sampled after all on-site adjustments have been made to themixture proportions, including the addition of mix water andadmixture
4、s. This practice is not satisfactory for making speci-mens from concrete not having measurable slump or requiringother sizes or shapes of specimens.1.3 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
5、equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the us
6、er of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.(WarningFresh hydraulic cementitious mixtures are causticand may cause chemical burns to exposed skin and tissue uponprolonged exposure.2)
7、1.5 The text of this standard references notes which provideexplanatory material. These notes shall not be considered asrequirements of the standard.1.6 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision
8、 on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:3C125 Terminology Relating to Concrete and Concrete Ag-gregatesC138/C138M Test Method
9、for Density (Unit Weight), Yield,and Air Content (Gravimetric) of ConcreteC143/C143M Test Method for Slump of Hydraulic-CementConcreteC172/C172M Practice for Sampling Freshly Mixed Con-creteC173/C173M Test Method forAir Content of Freshly MixedConcrete by the Volumetric MethodC231/C231M Test Method
10、forAir Content of Freshly MixedConcrete by the Pressure MethodC330/C330M Specification for Lightweight Aggregates forStructural ConcreteC403/C403M Test Method for Time of Setting of ConcreteMixtures by Penetration ResistanceC470/C470M Specification for Molds for Forming ConcreteTest Cylinders Vertic
11、allyC511 Specification for Mixing Rooms, Moist Cabinets,Moist Rooms, and Water Storage Tanks Used in theTesting of Hydraulic Cements and ConcretesC617/C617M Practice for Capping Cylindrical ConcreteSpecimensC1064/C1064M Test Method for Temperature of FreshlyMixed Hydraulic-Cement ConcreteC1077 Pract
12、ice for Agencies Testing Concrete and ConcreteAggregates for Use in Construction and Criteria forTesting Agency EvaluationC1758/C1758M Practice for Fabricating Test Specimenswith Self-Consolidating Concrete2.2 American Concrete Institute Publication:4309R Guide for Consolidation of Concrete1This pra
13、ctice is under the jurisdiction of ASTM Committee C09 on Concreteand Concrete Aggregates and is the direct responsibility of Subcommittee C09.61on Testing for Strength.Current edition approved Jan. 1, 2018. Published February 2018. Originallyapproved in 1920. Last previous edition approved in 2017 a
14、s C31/C31M17. DOI:10.1520/C0031_C0031M-18.2See Section 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 o
15、f ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.4Available from American Concrete Institute (ACI), P.O. Box 9094, FarmingtonHills, MI 48333-9094, http:/www.aci-int.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM
16、International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standa
17、rds, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13. Terminology3.1 For definitions of terms used in this practice, refer toTerminology C125.4. Significance and Use4.1 This practice provides standardized requirements formaking, curing
18、, protecting, and transporting concrete testspecimens under field conditions.4.2 If the specimens are made and standard cured, asstipulated herein, the resulting strength test data when thespecimens are tested are able to be used for the followingpurposes:4.2.1 Acceptance testing for specified stren
19、gth,4.2.2 Checking adequacy of mixture proportions forstrength, and4.2.3 Quality control.4.3 If the specimens are made and field cured, as stipulatedherein, the resulting strength test data when the specimens aretested are able to be used for the following purposes:4.3.1 Determination of whether a s
20、tructure is capable ofbeing put in service,4.3.2 Comparison with test results of standard cured speci-mens or with test results from various in-place test methods,4.3.3 Adequacy of curing and protection of concrete in thestructure, or4.3.4 Form or shoring removal time requirements.5. Apparatus5.1 Mo
21、lds, GeneralMolds for specimens or fasteningsthereto in contact with the concrete shall be made of steel, castiron, or other nonabsorbent material, nonreactive with concretecontaining portland or other hydraulic cements. Molds shallhold their dimensions and shape under all conditions of use.Molds sh
22、all be watertight during use as judged by their abilityto hold water poured into them. Provisions for tests of waterleakage are given in the Test Methods for Elongation,Absorption, and Water Leakage section of Specification C470/C470M. A suitable sealant, such as heavy grease, modelingclay, or micro
23、crystalline wax shall be used where necessary toprevent leakage through the joints. Positive means shall beprovided to hold base plates firmly to the molds. Reusablemolds shall be lightly coated with mineral oil or a suitablenonreactive form release material before use.5.2 Cylinder MoldsMolds for ca
24、sting concrete test speci-mens shall conform to the requirements of SpecificationC470/C470M.5.3 Beam MoldsBeam molds shall be of the shape anddimensions required to produce the specimens stipulated in 6.2.The inside surfaces of the molds shall be smooth. The sides,bottom, and ends shall be at right
25、angles to each other and shallbe straight and true and free of warpage. Maximum variationfrom the nominal cross section shall not exceed 3 mm 18 in.for molds with depth or breadth of 150 mm 6 in. or more.Molds shall produce specimens at least as long but not morethan 2 mm 116 in. shorter than the re
26、quired length in 6.2.5.4 Tamping RodA round, smooth, straight, steel rod witha diameter conforming to the requirements in Table 1. Thelength of the tamping rod shall be at least 100 mm 4 in.greater than the depth of the mold in which rodding is beingperformed, but not greater than 600 mm 24 in. in o
27、veralllength (see Note 1). The rod shall have the tamping end or bothends rounded to a hemispherical tip of the same diameter as therod.NOTE 1A rod length of 400 mm 16 in. to 600 mm 24 in. meets therequirements of the following: Practice C31/C31M, Test Method C138/C138M, Test Method C143/C143M, Test
28、 Method C173/C173M, and TestMethod C231/C231M.5.5 VibratorsInternal vibrators shall be used. The vibratorfrequency shall be at least 150 Hz 9000 vibrations per minutewhile the vibrator is operating in the concrete. The diameter ofa round vibrator shall be no more than one-fourth the diameterof the c
29、ylinder mold or one-fourth the width of the beam mold.Other shaped vibrators shall have a perimeter equivalent to thecircumference of an appropriate round vibrator. The combinedlength of the vibrator shaft and vibrating element shall exceedthe depth of the section being vibrated by at least 75 mm 3i
30、n. The vibrator frequency shall be checked periodically witha vibrating-reed tachometer or other suitable device.NOTE 2For information on size and frequency of various vibratorsand a method to periodically check vibrator frequency see ACI 309R.5.6 MalletA mallet with a rubber or rawhide head weigh-i
31、ng 0.6 6 0.2 kg 1.25 6 0.50 lb shall be used.5.7 Placement Toolsof a size large enough so each amountof concrete obtained from the sampling receptacle is represen-tative and small enough so concrete is not spilled duringplacement in the mold. For placing concrete in a cylinder mold,the acceptable to
32、ol is a scoop. For placing concrete in a beammold, either a shovel or scoop is permitted.5.8 Finishing Toolsa handheld float or a trowel.5.9 Slump ApparatusThe apparatus for measurement ofslump shall conform to the requirements of Test MethodC143/C143M.5.10 Sampling ReceptacleThe receptacle shall be
33、 a suit-able heavy gauge metal pan, wheelbarrow, or flat, cleannonabsorbent board of sufficient capacity to allow easy remix-ing of the entire sample with a shovel or trowel.5.11 Air Content ApparatusThe apparatus for measuringair content shall conform to the requirements of Test MethodsC173/C173M o
34、r C231/C231M.5.12 Temperature Measuring DevicesThe temperaturemeasuring devices shall conform to the applicable require-ments of Test Method C1064/C1064M.6. Testing Requirements6.1 Cylindrical SpecimensCompressive or splitting tensilestrength specimens shall be cylinders cast and allowed to set inTA
35、BLE 1 Tamping Rod Diameter RequirementsDiameter of Cylinderor Width of Beammm in.Diameter or Rodmm in.200 8 3 or more equal depths,each not to exceed150 mm 6 in.see 9.3TABLE 5 Molding Requirements by VibrationSpecimen Typeand SizeNumber ofLayersNumber ofVibratorInsertionsper LayerApproximate Depth o
36、fLayer, mm in.Cylinders:Diameter, mm in.100 4 2 1 one-half depth of specimen150 6 2 2 one-half depth of specimen225 9 2 4 one-half depth of specimenBeams:Width, mm in.100 4 to200 81 see 9.4.2 depth of specimenover 200 8 2 or more see 9.4.2 200 8 as near aspracticableC31/C31M 1849.5.1 CylindersAfter
37、consolidation, finish the top surfacesby striking them off with the tamping rod where the consis-tency of the concrete permits or with a handheld float or trowel.If desired, cap the top surface of freshly made cylinders with athin layer of stiff portland cement paste which is permitted toharden and
38、cure with the specimen. See section on CappingMaterials of Practice C617/C617M.9.5.2 BeamsAfter consolidation of the concrete, use ahandheld float or trowel to strike off the top surface to therequired tolerance to produce a flat, even surface.9.6 IdentificationMark the specimens to positively iden-
39、tify them and the concrete they represent. Use a method thatwill not alter the top surface of the concrete. Do not mark theremovable caps. Upon removal of the molds, mark the testspecimens to retain their identities.10. Curing10.1 Standard CuringStandard curing is the curingmethod used when the spec
40、imens are made and cured for thepurposes stated in 4.2.10.1.1 StorageIf specimens cannot be molded at the placewhere they will receive initial curing, immediately afterfinishing move the specimens to an initial curing place forstorage. The supporting surface on which specimens are storedshall be lev
41、el to within 20 mm/m 14 in. ft. If cylinders in thesingle use molds are moved, lift and support the cylinders fromthe bottom of the molds with a large trowel or similar device.If the top surface is marred during movement to place of initialstorage, immediately refinish.10.1.2 Initial CuringImmediate
42、ly after molding andfinishing, the specimens shall be stored for a period up to 48 hin a temperature range from 16 to 27C 60 to 80F and in anenvironment preventing moisture loss from the specimens. Forconcrete mixtures with a specified strength of 40 MPa 6000psi or greater, the initial curing temper
43、ature shall be between20 and 26C 68 and 78F. Various procedures are capable ofbeing used during the initial curing period to maintain thespecified moisture and temperature conditions. An appropriateprocedure or combination of procedures shall be used (Note 7).Shield all specimens from the direct sun
44、light and, if used,radiant heating devices. The storage temperature shall becontrolled by use of heating and cooling devices, as necessary.Record the temperature using a maximum-minimum thermom-eter. If cardboard molds are used, protect the outside surface ofthe molds from contact with wet burlap or
45、 other sources ofwater.NOTE 7Asatisfactory moisture environment can be created during theinitial curing of the specimens by one or more of the followingprocedures: (1) immediately immerse molded specimens with plastic lidsin water saturated with calcium hydroxide, (2) store in properly con-structed
46、wooden boxes or structures, (3) place in damp sand pits, (4) coverwith removable plastic lids, (5) place inside plastic bags, or (6) cover withplastic sheets or nonabsorbent plates if provisions are made to avoiddrying and damp burlap is used inside the enclosure, but the burlap isprevented from con
47、tacting the concrete surfaces. A satisfactory tempera-ture environment can be controlled during the initial curing of thespecimens by one or more of the following procedures: (1) use ofventilation, (2) use of ice, (3) use of thermostatically controlled heating orcooling devices, or (4) use of heatin
48、g methods such as stoves or lightbulbs. Other suitable methods may be used provided the requirementslimiting specimen storage temperature and moisture loss are met. Forconcrete mixtures with a specified strength of 40 MPa 6000 psi orgreater, heat generated during the early ages may raise the tempera
49、tureabove the required storage temperature. Immersion in water saturated withcalcium hydroxide may be the easiest method to maintain the requiredstorage temperature. When specimens are to be immersed in watersaturated with calcium hydroxide, specimens in cardboard molds or othermolds that expand when immersed in water should not be used. Early-agestrength test results may be lower when stored at 16C 60F and higherwhen stored at 27C 80F. On the other hand, at later ages, test resultsmay
