1、Designation: C31/C31M 15C31/C31M 15aStandard 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
2、of last revision. 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 procedu
3、res for making and curing cylinder and beam specimens from representative samples of freshconcrete for a construction project.1.2 The concrete used to make the molded specimens shall be sampled after all on-site adjustments have been made to themixture proportions, including the addition of mix wate
4、r and admixtures. This practice is not satisfactory for making specimensfrom concrete not having measurable slump or requiring other sizes or shapes of specimens.1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in eachsystem ma
5、y not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from thetwo systems may result in non-conformance with the standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the respo
6、nsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use. (WarningFresh hydraulic cementitious mixtures are caustic and may cause chemical burns to exposedskin and tissue upon prolonged exposure.2
7、)1.5 The text of this standard references notes which provide explanatory material. These notes shall not be considered asrequirements of the standard.2. Referenced Documents2.1 ASTM Standards:3C125 Terminology Relating to Concrete and Concrete AggregatesC138/C138M Test Method for Density (Unit Weig
8、ht), Yield, and Air Content (Gravimetric) of ConcreteC143/C143M Test Method for Slump of Hydraulic-Cement ConcreteC172/C172M Practice for Sampling Freshly Mixed ConcreteC173/C173M Test Method for Air Content of Freshly Mixed Concrete by the Volumetric MethodC231/C231M Test Method for Air Content of
9、Freshly Mixed Concrete by the Pressure MethodC330/C330M Specification for Lightweight Aggregates for Structural ConcreteC403/C403M Test Method for Time of Setting of Concrete Mixtures by Penetration ResistanceC470/C470M Specification for Molds for Forming Concrete Test Cylinders VerticallyC511 Speci
10、fication for Mixing Rooms, Moist Cabinets, Moist Rooms, and Water Storage Tanks Used in the Testing of HydraulicCements and ConcretesC617/C617M Practice for Capping Cylindrical Concrete SpecimensC1064/C1064M Test Method for Temperature of Freshly Mixed Hydraulic-Cement ConcreteC1077 Practice forAgen
11、cies Testing Concrete and ConcreteAggregates for Use in Construction and Criteria for TestingAgencyEvaluation2.2 American Concrete Institute Publication:4309R Guide for Consolidation of Concrete1 This practice is under the jurisdiction ofASTM Committee C09 on Concrete and ConcreteAggregates and is t
12、he direct responsibility of Subcommittee C09.61 on Testingfor Strength.Current edition approved July 1, 2015Nov. 15, 2015. Published August 2015January 2016. Originally approved in 1920. Last previous edition approved in 20122015 asC31/C31M12.15. DOI: 10.1520/C0031_C0031M-15.10.1520/C0031_C0031M-15A
13、.2 See 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 serviceastm.org. For Annual Book of ASTM Standardsvolume information, refe
14、r to the standards Document Summary page on the ASTM website.4 Available from American Concrete Institute (ACI), P.O. Box 9094, Farmington Hills, MI 48333-9094, http:/www.aci-int.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of w
15、hat changes have been made to the previous version. Becauseit 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 t
16、he official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13. Terminology3.1 For definitions of terms used in this practice, refer to Terminology C125.4. Signi
17、ficance and Use4.1 This practice provides standardized requirements for making, curing, protecting, and transporting concrete test specimensunder field conditions.4.2 If the specimens are made and standard cured, as stipulated herein, the resulting strength test data when the specimens aretested are
18、 able to be used for the following purposes:4.2.1 Acceptance testing for specified strength,4.2.2 Checking adequacy of mixture proportions for strength, and4.2.3 Quality control.4.3 If the specimens are made and field cured, as stipulated herein, the resulting strength test data when the specimens a
19、re testedare able to be used for the following purposes:4.3.1 Determination of whether a structure is capable of being put in service,4.3.2 Comparison with test results of standard cured specimens or with test results from various in-place test methods,4.3.3 Adequacy of curing and protection of conc
20、rete in the structure, or4.3.4 Form or shoring removal time requirements.5. Apparatus5.1 Molds, GeneralMolds for specimens or fastenings thereto in contact with the concrete shall be made of steel, cast iron,or other nonabsorbent material, nonreactive with concrete containing portland or other hydra
21、ulic cements. Molds shall hold theirdimensions and shape under all conditions of use. Molds shall be watertight during use as judged by their ability to hold waterpoured into them. Provisions for tests of water leakage are given in the Test Methods for Elongation, Absorption, and WaterLeakage sectio
22、n of Specification C470/C470M. A suitable sealant, such as heavy grease, modeling clay, or microcrystalline waxshall be used where necessary to prevent leakage through the joints. Positive means shall be provided to hold base plates firmlyto the molds. Reusable molds shall be lightly coated with min
23、eral oil or a suitable nonreactive form release material before use.5.2 Cylinder MoldsMolds for casting concrete test specimens shall conform to the requirements of SpecificationC470/C470M.5.3 Beam MoldsBeam molds shall be of the shape and dimensions required to produce the specimens stipulated in 6
24、.2. Theinside surfaces of the molds shall be smooth. The sides, bottom, and ends shall be at right angles to each other and shall be straightand true and free of warpage. Maximum variation from the nominal cross section shall not exceed 3 mm 18 in. for molds withdepth or breadth of 150 mm 6 in. or m
25、ore. Molds shall produce specimens at least as long but not more than 2 mm 116 in. shorterthan the required length in 6.2.5.4 Tamping RodA round, smooth, straight, steel rod with a diameter conforming to the requirements in Table 1. The lengthof the tamping rod shall be at least 100 mm 4 in. greater
26、 than the depth of the mold in which rodding is being performed, butnot greater than 600 mm 24 in. in overall length (see Note 1). The rod shall have the tamping end or both ends rounded to ahemispherical tip of the same diameter as the rod.NOTE 1Arod length of 400 mm 16 in. to 600 mm 24 in. meets t
27、he requirements of the following: Practice C31/C31M, Test Method C138/C138M,Test Method C143/C143M, Test Method C173/C173M, and Test Method C231/C231M.5.5 VibratorsInternal vibrators shall be used. The vibrator frequency shall be at least 9000 150 Hz 9000 vibrations per minute150 Hz minute while the
28、 vibrator is operating in the concrete. The diameter of a round vibrator shall be no more than one-fourththe diameter of the cylinder mold or one-fourth the width of the beam mold. Other shaped vibrators shall have a perimeterequivalent to the circumference of an appropriate round vibrator. The comb
29、ined length of the vibrator shaft and vibrating elementTABLE 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 9.3C31/C31M 15a49.3 Casting BeamsSelect the proper tamping rod from 5.4 and Ta
30、ble 1 or proper vibrator from 5.5. Determine the method ofconsolidation from Table 23, unless another method is specified. If the method of consolidation is rodding, determine the moldingrequirements from Table 34. If the method of consolidation is vibration, determine the molding requirements from
31、Table 45.Determine the number of roddings per layer, one for each 14 cm2 2 in.2 of the top surface area of the beam. Select a placementtool as described in 5.7. Using the scoop or shovel, place the concrete in the mold to the height required for each layer. Place theconcrete so that it is uniformly
32、distributed within each layer with minimal segregation. Each layer shall be consolidated as required.In placing the final layer, add an amount of concrete that will fill the mold after consolidation.9.4 ConsolidationThe methods of consolidation for this practice are rodding or internal vibration.9.4
33、.1 RoddingPlace the concrete in the mold in the required number of layers of approximately equal volume. Rod each layeruniformly over the cross section with the rounded end of the rod using the required number of strokes. Rod the bottom layerthroughout its depth. In rodding this layer, use care not
34、to damage the bottom of the mold. For each upper layer, allow the rod topenetrate through the layer being rodded and into the layer below approximately 25 mm 1 in. After each layer is rodded, tapthe outsides of the mold lightly 10 to 15 times with the mallet to close any holes left by rodding and to
35、 release any large air bubblesthat may have been trapped. Use an open hand to tap cylinder molds that are susceptible to denting or other permanent distortionif tapped with a mallet. After tapping, spade each layer of the concrete along the sides and ends of beam molds with a trowel orother suitable
36、 tool. Underfilled molds shall be adjusted with representative concrete during consolidation of the top layer.Overfilled molds shall have excess concrete removed.9.4.2 VibrationMaintain a uniform duration of vibration for the particular kind of concrete, vibrator, and specimen moldinvolved. The dura
37、tion of vibration required will depend upon the workability of the concrete and the effectiveness of the vibrator.Usually sufficient vibration has been applied as soon as the surface of the concrete has become relatively smooth and large airbubbles cease to break through the top surface. Continue vi
38、bration only long enough to achieve proper consolidation of theconcrete (see Note 57). Fill the molds and vibrate in the required number of approximately equal layers. Place all the concrete foreach layer in the mold before starting vibration of that layer. In compacting the specimen, insert the vib
39、rator slowly and do notallow it to rest on the bottom or sides of the mold. Slowly withdraw the vibrator so that no large air pockets are left in the specimen.When placing the final layer, avoid overfilling by more than 6 mm 14 in.NOTE 7Generally, no more than 5 s of vibration should be required for
40、 each insertion to adequately consolidate concrete with a slump greater than75 mm 3 in. Longer times may be required for lower slump concrete, but the vibration time should rarely have to exceed 10 s per insertion.9.4.2.1 CylindersThe number of insertions of the vibrator per layer is given in Table
41、45. When more than one insertion perlayer is required distribute the insertion uniformly within each layer. Allow the vibrator to penetrate through the layer beingvibrated, and into the layer below, about 25 mm 1 in. After each layer is vibrated, tap the outsides of the mold at least 10 timeswith th
42、e mallet, to close holes that remain and to release entrapped air voids. Use an open hand to tap molds that are susceptibleto denting or other permanent distortion if tapped with a mallet.9.4.2.2 BeamsInsert the vibrator at intervals not exceeding 150 mm 6 in. along the center line of the long dimen
43、sion of thespecimen. For specimens wider than 150 mm 6 in., use alternating insertions along two lines. Allow the shaft of the vibrator topenetrate into the bottom layer about 25 mm 1 in. After each layer is vibrated, tap the outsides of the mold sharply at least 10times with the mallet to close hol
44、es left by vibrating and to release entrapped air voids.9.5 FinishingPerform all finishing with the minimum manipulation necessary to produce a flat even surface that is level withthe rim or edge of the mold and that has no depressions or projections larger than 3.3 mm 18 in.TABLE 45 Molding Require
45、ments by VibrationSpecimen Typeand SizeNumber ofLayersNumber ofVibratorInsertionsper LayerApproximate Depth ofLayer, mm in.Cylinders:Diameter, mm in.100 4 2 1 one-half depth of specimen100 4 2 1 one-half depth of specimen150 6 2 2 one-half depth of specimen225 9 2 4 one-half depth of specimen2256 9
46、2 4 one-half depth of specimenBeams:Width, mm in.150 6 to200 81 see 9.4.2 depth of specimen100 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 15a59.5.1 CylindersAfter consolidation, finish the top surfaces by striking them off with the tampin
47、g rod where the consistencyof the concrete permits or with a handheld float or trowel. If desired, cap the top surface of freshly made cylinders with a thin layerof stiff portland cement paste which is permitted to harden and cure with the specimen. See section on Capping Materials ofPractice C617/C
48、617M.9.5.2 BeamsAfter consolidation of the concrete, use a handheld float or trowel to strike off the top surface to the requiredtolerance to produce a flat, even surface.9.6 IdentificationMark the specimens to positively identify them and the concrete they represent. Use a method that will notalter
49、 the top surface of the concrete. Do not mark the removable caps. Upon removal of the molds, mark the test specimens to retaintheir identities.10. Curing10.1 Standard CuringStandard curing is the curing method used when the specimens are made and cured for the purposesstated in 4.2.10.1.1 StorageIf specimens cannot be molded at the place where they will receive initial curing, immediately after finishingmove the specimens to an initial curing place for storage. The supporting
