1、Designation:C31/C31M10 Designation: C31/C31M 12Standard 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
2、, the year 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 Department of Defense.1. Scope*1.1 This practice covers p
3、rocedures 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 mi
4、x water 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 eachsys
5、tem may 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
6、 responsibilityof 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 expo
7、sure.2)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 (Uni
8、t Weight), Yield, and Air Content (Gravimetric) of ConcreteC143/C143M Test Method for Slump of Hydraulic-Cement ConcreteC172 Practice for Sampling Freshly Mixed ConcreteC173/C173M Test Method for Air Content of Freshly Mixed Concrete by the Volumetric MethodC231 Test Method for Air Content of Freshl
9、y Mixed Concrete by the Pressure MethodC330 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 Specification for
10、 Mixing Rooms, Moist Cabinets, Moist Rooms, and Water Storage Tanks Used in the Testing ofHydraulic Cements and ConcretesC617 Practice for Capping Cylindrical Concrete SpecimensC1064/C1064M Test Method for Temperature of Freshly Mixed Hydraulic-Cement Concrete Test Method for Temperature ofFreshly M
11、ixed Hydraulic-Cement ConcreteC1077 Practice forAgencies Testing Concrete and ConcreteAggregates for Use in Construction and Criteria for TestingAgencyEvaluation2.2 American Concrete Institute Publication:4CP-1Concrete Field Testing Technician, Grade I309R Guide for Consolidation of Concrete1This pr
12、actice is under the jurisdiction of ASTM Committee C09 on Concrete and Concrete Aggregates and is the direct responsibility of Subcommittee C09.61 onTesting for Strength.Current edition approved Oct.July 1, 2010.2012. Published November 2010.September 2012. Originally approved in 1920. Last previous
13、 edition approved in 2009 asC31/C31M109. DOI: 10.1520/C0031_C0031M-102.2See 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, or contact ASTM Customer Service at ser
14、viceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.4Available from American Concrete Institute (ACI), P.O. Box 9094, Farmington Hills, MI 48333-9094, http:/www.aci-int.org.1This document is not an ASTM standard and is i
15、ntended only to provide the user of an ASTM standard an indication of what 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 cu
16、rrent versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3. Terminology3.1 For defini
17、tions of terms used in this practice, refer to Terminology C125.4. Significance 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 h
18、erein, the resulting strength test data when the specimens aretested are 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
19、stipulated herein, the resulting strength test data when the specimens are 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 vario
20、us in-place test methods,4.3.3 Adequacy of curing and protection of concrete in the structure, or4.3.4 Form or shoring removal time requirements.5. Apparatus5.1 Molds, General Molds for specimens or fastenings thereto in contact with the concrete shall be made of steel, cast iron,or other nonabsorbe
21、nt material, nonreactive with concrete containing portland or other hydraulic 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 give
22、n in the Test Methods for Elongation, Absorption, and WaterLeakage section 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 p
23、lates firmlyto the molds. Reusable molds shall be lightly coated with mineral oil or a suitable nonreactive form release material before use.5.2 Cylinder Molds Molds for casting concrete test specimens shall conform to the requirements of SpecificationC470/C470M.5.3 Beam MoldsBeam molds shall be of
24、the shape and dimensions required to produce the specimens stipulated in 6.2. 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
25、not exceed18 in. 3 mm for molds withdepth or breadth of 6 in. 150 mm or more. Molds shall produce specimens at least as long but not more than116 in. 2 mmshorter than the required length in 6.2.5.4 Tamping RodA round, smooth, straight, steel rod with a diameter conforming to the requirements in Tabl
26、e 1. The lengthof the tamping rod shall be at least 4 in. 100 mm greater than the depth of the mold in which rodding is being performed, butnot greater than 24 in. 600 mm in overall length (see Note 1). The rod shall have the tamping end or both ends rounded to ahemispherical tip of the same diamete
27、r as the rod.NOTE 1Arod length of 16 in. 400 mm to 24 in. 600 mm meets the requirements of the following: Practice C31/C31M, Test Method C138/C138M,Test Method C143/C143M, Test Method C173/C173M, and Test Method C231.5.5 VibratorsInternal vibrators shall be used. The vibrator frequency shall be at l
28、east 9000 vibrations per minute 150 Hzwhile the vibrator is operating in the concrete. The diameter of a round vibrator shall be no more than one-fourth the diameter ofthe cylinder mold or one-fourth the width of the beam mold. Other shaped vibrators shall have a perimeter equivalent to thecircumfer
29、ence of an appropriate round vibrator. The combined length of the vibrator shaft and vibrating element shall exceed thedepth of the section being vibrated by at least 3 in. 75 mm. The vibrator frequency shall be checked periodically with avibrating-reed tachometer or other suitable device.NOTE 2For
30、information on size and frequency of various vibrators and a method to periodically check vibrator frequency see ACI 309R.5.6 MalletA mallet with a rubber or rawhide head weighing 1.25 6 0.50 lb 0.6 6 0.2 kg shall be used.5.7 Placement Toolsof a size large enough so each amount of concrete obtained
31、from the sampling receptacle is representativeand small enough so concrete is not spilled during placement in the mold. For placing concrete in a cylinder mold, the acceptabletool is a scoop. For placing concrete in a beam mold, either a shovel or scoop is permitted.TABLE 1 Tamping Rod Diameter Requ
32、irementsDiameter of Cylinderor Width of Beamin. mmDiameter or Rodin. mm8 200 3 or more equal depths,each not to exceed6 in. 150 mm.see 9.3TABLE 4 Molding Requirements by VibrationSpecimen Typeand SizeNumber ofLayersNumber ofVibratorInsertionsper LayerApproximate Depth ofLayer, in. mmCylinders:Diamet
33、er, 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 specimenBeams: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 1249.4.2.1 CylindersThe number of insertions of the
34、vibrator per layer is given in Table 4. 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 1 in. 25 mm. After each layer is vibrated, tap the outsides
35、 of the mold at least 10 timeswith the mallet, to close holes that remain and to release entrapped air voids. Use an open hand to tap cardboard and single-usemetal molds that are susceptible to damage if tapped with a mallet.9.4.2.2 BeamsInsert the vibrator at intervals not exceeding 6 in. 150 mm al
36、ong the center line of the long dimension of thespecimen. For specimens wider than 6 in., use alternating insertions along two lines. Allow the shaft of the vibrator to penetrateinto the bottom layer about 1 in. 25 mm. After each layer is vibrated, tap the outsides of the mold sharply at least 10 ti
37、mes withthe mallet to close holes 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 than18 in.
38、3.3 mm.9.5.1 CylindersAfter consolidation, finish the top surfaces by striking them off with the tamping 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 whic
39、h is permitted to harden and cure with the specimen. See section on Capping Materials ofPractice C617.9.5.2 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 Identification Mark the spec
40、imens to positively identify them and the concrete they represent. Use a method that will notalter 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 Curing Standard curing is the curin
41、g 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 surface on which spe
42、cimens are stored shall be level towithin14 in. per ft 20 mm per m. If cylinders in the single use molds are moved, lift and support the cylinders from the bottomof the molds with a large trowel or similar device. If the top surface is marred during movement to place of initial storage,immediately r
43、efinish.10.1.2 Initial Curing Immediately after molding and finishing, the specimens shall be stored for a period up to 48 h in atemperature range from 60 and 80 F 16 and 27 C and in an environment preventing moisture loss from the specimens. Forconcrete mixtures with a specified strength of 6000 ps
44、i 40 MPa or greater, the initial curing temperature shall be between 68 and78 F 20 and 26 C. Various procedures are capable of being used during the initial curing period to maintain the specifiedmoisture and temperature conditions. An appropriate procedure or combination of procedures shall be used
45、 (Note 6). Shield allspecimens from the direct sunlight and, if used, radiant heating devices. The storage temperature shall be controlled by use ofheating and cooling devices, as necessary. Record the temperature using a maximum-minimum thermometer. If cardboard moldsare used, protect the outside s
46、urface of the molds from contact with wet burlap or other sources of water.NOTE 6A satisfactory moisture environment can be created during the initial curing of the specimens by one or more of the following procedures:(1) immediately immerse molded specimens with plastic lids in water saturated with
47、 calcium hydroxide, (2) store in properly constructed wooden boxesor structures, (3) place in damp sand pits, (4) cover with removable plastic lids, (5) place inside plastic bags, or (6) cover with plastic sheets ornonabsorbent plates if provisions are made to avoid drying and damp burlap is used in
48、side the enclosure, but the burlap is prevented from contacting theconcrete surfaces. A satisfactory temperature environment can be controlled during the initial curing of the specimens by one or more of the followingprocedures: (1) use of ventilation, (2) use of ice, (3) use of thermostatically con
49、trolled heating or cooling devices, or (4) use of heating methods suchas stoves or light bulbs. Other suitable methods may be used provided the requirements limiting specimen storage temperature and moisture loss are met.For concrete mixtures with a specified strength of 6000 psi 40 MPa or greater, heat generated during the early ages may raise the temperature abovethe required storage temperature. Immersion in water saturated with calcium hydroxide may be the easiest method to maintain th
