1、Designation: C31/C31M 10Standard 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 Department of Defense.1. Scope*1.1 This practice covers procedures for making an
3、d 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 andadmixtures. Th
4、is 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 equiv
5、alents; 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 user of
6、 this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. (WarningFreshhydraulic cementitious mixtures are caustic and may causechemical burns to exposed skin and tissue upon prolongedexposure.2)1.5 The text of this
7、standard references notes which provideexplanatory material. These notes shall not be considered asrequirements of the standard.2. Referenced Documents2.1 ASTM Standards:3C125 Terminology Relating to Concrete and Concrete Ag-gregatesC138/C138M Test Method for Density (Unit Weight),Yield, and Air Con
8、tent (Gravimetric) of ConcreteC143/C143M Test Method for Slump of Hydraulic-CementConcreteC172 Practice for Sampling Freshly Mixed ConcreteC173/C173M Test Method for Air Content of FreshlyMixed Concrete by the Volumetric MethodC231 Test Method for Air Content of Freshly Mixed Con-crete by the Pressu
9、re MethodC330 Specification for Lightweight Aggregates for Struc-tural ConcreteC403/C403M Test Method for Time of Setting of ConcreteMixtures by Penetration ResistanceC470/C470M Specification for Molds for Forming Con-crete Test Cylinders VerticallyC511 Specification for Mixing Rooms, Moist Cabinets
10、,Moist Rooms, and Water Storage Tanks Used in theTesting of Hydraulic Cements and ConcretesC617 Practice for Capping Cylindrical Concrete SpecimensC1064/C1064M Test Method for Temperature of FreshlyMixed Hydraulic-Cement Concrete2.2 American Concrete Institute Publication:4CP-1 Concrete Field Testin
11、g Technician, Grade I309R Guide for Consolidation of Concrete3. 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, protecting, and transporting concrete testspecimens u
12、nder 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 strength,4.2.2 Checking adequacy of mixture proportions fors
13、trength, and1This practice 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 Oct. 1, 2010. Published November 2010. Originallyapproved in 1920. Last previous editi
14、on approved in 2009 as C31/C31M09. DOI:10.1520/C0031_C0031M-10.2See 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.o
15、rg. For Annual Book of 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.1*A Summary of Changes section appears at the end of this s
16、tandard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.2.3 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 th
17、e following purposes:4.3.1 Determination of whether a structure 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
18、or shoring removal time requirements.5. Apparatus5.1 Molds, General Molds 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 d
19、imensions and shape under all conditions of use.Molds shall 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, Absorp-tion, and Water Leakage section of Specification C470/C470M.A suita
20、ble sealant, such as heavy grease, modeling clay, ormicrocrystalline wax shall be used where necessary to preventleakage through the joints. Positive means shall be provided tohold base plates firmly to the molds. Reusable molds shall belightly coated with mineral oil or a suitable nonreactive formr
21、elease material before use.5.2 Cylinder Molds Molds for casting 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 shal
22、l be smooth. The sides,bottom, and ends shall be at right angles to each other and shallbe straight and true and free of warpage. Maximum variationfrom the nominal cross section shall not exceed18 in. 3 mmfor molds with depth or breadth of 6 in. 150 mm or more.Molds shall produce specimens at least
23、as long but not morethan116 in. 2 mm shorter than the required 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 4 in. 100 mmgreater than the depth of the mold in which rodding is
24、 beingperformed, but not greater than 24 in. 600 mm in overalllength (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 16 in. 400 mm to 24 in. 600 mm meets therequirements of the following: Practice C31/C3
25、1M, Test Method C138/C138M, Test Method C143/C143M, Test Method C173/C173M, and TestMethod C231.5.5 VibratorsInternal vibrators shall be used. The vibratorfrequency shall be at least 9000 vibrations per minute 150 Hzwhile the vibrator is operating in the concrete. The diameter ofa round vibrator sha
26、ll be no more than one-fourth the diameterof the cylinder 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
27、of the section being vibrated by at least 3 in. 75mm. The vibrator frequency shall be checked periodicallywith a 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 M
28、alletA mallet with a rubber or rawhide head weigh-ing 1.25 6 0.50 lb 0.6 6 0.2 kg shall be used.5.7 Placement Toolsof a size large enough so eachamount of concrete obtained from the sampling receptacle isrepresentative and small enough so concrete is not spilledduring placement in the mold. For plac
29、ing concrete in acylinder mold, the acceptable tool is a scoop. For placingconcrete in a beam mold, either a shovel or scoop is permitted.5.8 Finishing Toolsa handheld float or a trowel.5.9 Slump Apparatus The apparatus for measurement ofslump shall conform to the requirements of Test MethodC143/C14
30、3M.5.10 Sampling ReceptacleThe receptacle shall be 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 confo
31、rm to the requirements of Test MethodsC173/C173M or C231.5.12 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 ten-sile strength specimens s
32、hall be cylinders cast and allowed toset in an upright position. The number and size of cylinderscast shall be as directed by the specifier of the tests. In addition,the length shall be twice the diameter and the cylinder diametershall be at least 3 times the nominal maximum size of thecoarse aggreg
33、ate. When the nominal maximum size of thecoarse aggregate exceeds 2 in. 50 mm, the concrete sampleshall be treated by wet sieving through a 2-in. 50-mm sieveas described in Practice C172. For acceptance testing forspecified compressive strength, cylinders shall be 6 by 12 in.150 by 300 mm or 4 3 8 i
34、n. 100 3 200 mm (Note 3).NOTE 3When molds in SI units are required and not available,equivalent inch-pound unit size mold should be permitted.6.2 Beam Specimens Flexural strength specimens shall bebeams of concrete cast and hardened in the horizontal position.The number of beams cast shall be as dir
35、ected by the specifierof the tests. The length shall be at least 2 in. 50 mm greaterthan three times the depth as tested. The ratio of width to depthTABLE 1 Tamping Rod Diameter RequirementsDiameter of Cylinderor Width of Beamin. mmDiameter or Rodin. mm8 200 3 or more equal depths,each not to exceed
36、6 in. 150 mm.see 9.3TABLE 4 Molding Requirements by VibrationSpecimen Typeand SizeNumber ofLayersNumber ofVibratorInsertionsper LayerApproximate Depth ofLayer, in. mmCylinders:Diameter, in. mm4 100 2 1 one-half depth of specimen6 150 2 2 one-half depth of specimen9 225 2 4 one-half depth of specimen
37、Beams:Width, in. mm6 150 to 8 200 1 see 9.4.2 depth of specimenover 8 200 2 or more see 9.4.2 8 200 as near aspracticableC31/C31M 103each layer is rodded, tap the outsides of the mold lightly 10 to15 times with the mallet to close any holes left by rodding andto release any large air bubbles that ma
38、y have been trapped.Use an open hand to tap light-gauge single-use cylinder moldswhich are susceptible to damage if tapped with a mallet. Aftertapping, spade each layer of the concrete along the sides andends of beam molds with a trowel or other suitable tool.Underfilled molds shall be adjusted with
39、 representative con-crete during consolidation of the top layer. Overfilled moldsshall have excess concrete removed.9.4.2 VibrationMaintain a uniform duration of vibrationfor the particular kind of concrete, vibrator, and specimen moldinvolved. The duration of vibration required will depend uponthe
40、workability of the concrete and the effectiveness of thevibrator. Usually sufficient vibration has been applied as soonas the surface of the concrete has become relatively smooth andlarge air bubbles cease to break through the top surface.Continue vibration only long enough to achieve proper con-sol
41、idation of the concrete (see Note 5). Fill the molds andvibrate in the required number of approximately equal layers.Place all the concrete for each layer in the mold before startingvibration of that layer. In compacting the specimen, insert thevibrator slowly and do not allow it to rest on the bott
42、om orsides of the mold. Slowly withdraw the vibrator so that no largeair pockets are left in the specimen. When placing the finallayer, avoid overfilling by more than14 in. 6 mm.NOTE 5Generally, no more than5sofvibration should be requiredfor each insertion to adequately consolidate concrete with a
43、slump greaterthan 3 in. 75 mm. Longer times may be required for lower slumpconcrete, but the vibration time should rarely have to exceed 10 s perinsertion.9.4.2.1 CylindersThe number of insertions of the vibratorper layer is given in Table 4. When more than one insertion perlayer is required distrib
44、ute the insertion uniformly within eachlayer. Allow the vibrator to penetrate through the layer beingvibrated, and into the layer below, about 1 in. 25 mm. Aftereach layer is vibrated, tap the outsides of the mold at least 10times with the mallet, to close holes that remain and to releaseentrapped a
45、ir voids. Use an open hand to tap cardboard andsingle-use metal molds that are susceptible to damage if tappedwith a mallet.9.4.2.2 BeamsInsert the vibrator at intervals not exceed-ing 6 in. 150 mm along the center line of the long dimensionof the specimen. For specimens wider than 6 in., use altern
46、at-ing insertions along two lines.Allow the shaft of the vibrator topenetrate into the bottom layer about 1 in. 25 mm. After eachlayer is vibrated, tap the outsides of the mold sharply at least 10times with the mallet to close holes left by vibrating and torelease entrapped air voids.9.5 FinishingPe
47、rform all finishing with the minimummanipulation necessary to produce a flat even surface that islevel with the rim or edge of the mold and that has nodepressions or projections larger than18 in. 3.3 mm.9.5.1 CylindersAfter consolidation, finish the top surfacesby striking them off with the tamping
48、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 cure with the specimen. See section on CappingMaterials of Practice C617.9.5
49、.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 Identification Mark the specimens to positively iden-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 Curing Standard curing is the
