1、Designation: C31/C31M 18C31/C31M 18aStandard 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, health, and environmental practices and determine the applicability ofregulatory limitations prior to use. (WarningFresh hydraulic cementitious mixtures are caustic and may cause chemical burnsto exposed skin and tissue upon prol
7、onged exposure.2)1.5 The text of this standard references notes which provide explanatory material. These notes shall not be considered asrequirements of the standard.1.6 This international standard was developed in accordance with internationally recognized principles on standardizationestablished
8、in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:3C125 Terminology Relating to Concrete and Concrete AggregatesC138/C138
9、M Test Method for Density (Unit Weight), 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/C
10、231M Test Method for Air Content of 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
11、 Test Cylinders VerticallyC511 Specification 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-C
12、ement Concrete1 This practice is under the jurisdiction ofASTM Committee C09 on Concrete and ConcreteAggregates and is the direct responsibility of Subcommittee C09.61 on Testingfor Strength.Current edition approved Jan. 1, 2018March 15, 2018. Published February 2018April 2018. Originally approved i
13、n 1920. Last previous edition approved in 20172018 asC31/C31M17.18. DOI: 10.1520/C0031_C0031M-18.10.1520/C0031_C0031M-18A.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, ww
14、w.astm.org, or contactASTM Customer Service at serviceastm.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 wh
15、at 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 th
16、e 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 States1C1077 Practice forAgencies Testing Concrete and ConcreteAggregates for Use in Construction and Criter
17、ia for TestingAgencyEvaluationC1611/C1611M Test Method for Slump Flow of Self-Consolidating ConcreteC1758/C1758M Practice for Fabricating Test Specimens with Self-Consolidating Concrete2.2 American Concrete Institute Publication:4309R Guide for Consolidation of Concrete3. Terminology3.1 For definiti
18、ons 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 her
19、ein, 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 st
20、ipulated 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 various
21、 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, GeneralMolds for specimens or fastenings thereto in contact with the concrete shall be made of steel, cast iron,or other nonabsorbent
22、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 given i
23、n 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 plat
24、es firmlyto the molds. Reusable molds shall be lightly coated with mineral 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
25、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 not
26、exceed 3 mm 18 in. for molds withdepth or breadth of 150 mm 6 in. or more. 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
27、1. The lengthof the tamping rod shall be at least 100 mm 4 in. greater 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
28、as the rod.NOTE 1Arod length of 400 mm 16 in. to 600 mm 24 in. 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/C231M.4 Available from American Concrete Institute (ACI), P.O. Box 9094, Farmington H
29、ills, MI 48333-9094, http:/www.aci-int.org.TABLE 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 ofV
30、ibratorInsertionsper LayerApproximate Depth ofLayer, 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 a
31、spracticableC31/C31M 18a59.5.1 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
32、 cement paste which is permitted to harden and cure with the specimen. See section on Capping Materials ofPractice C617/C617M.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 Iden
33、tificationMark the specimens 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 CuringStanda
34、rd 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 supportin
35、g surface on which specimens are stored shall be level towithin 20 mm/m 14 in.ft. If cylinders in the single use molds are moved, lift and support the cylinders from the bottom of themolds with a large trowel or similar device. If the top surface is marred during movement to place of initial storage
36、, immediatelyrefinish.10.1.2 Initial CuringImmediately after molding and finishing, the specimens shall be stored for a period up to 48 h in atemperature range from 16 to 27C 60 to 80F and in an environment preventing moisture loss from the specimens. For concretemixtures with a specified strength o
37、f 40 MPa 6000 psi or greater, the initial curing temperature shall be between 20 and 26C68 and 78F. Various procedures are capable of being used during the initial curing period to maintain the specified moisture andtemperature conditions. An appropriate procedure or combination of procedures shall
38、be used (Note 7). Shield all specimens fromthe direct sunlight and, if used, radiant heating devices. The storage temperature shall be controlled by use of heating and coolingdevices, as necessary. Record the temperature using a maximum-minimum thermometer. If cardboard molds are used, protect theou
39、tside surface of the molds from contact with wet burlap or other sources of water.NOTE 7A 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 saturat
40、ed with 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
41、used inside 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 thermostatica
42、lly controlled 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 40 MPa 6000 psi or gr
43、eater, 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 the required storagetemperature. When specimens are to be immersed in water saturated with calcium hy
44、droxide, specimens in cardboard molds or other molds that expandwhen immersed in water should not be used. Early-age strength test results may be lower when stored at 16C 60F and higher when stored at 27C80F. On the other hand, at later ages, test results may be lower for higher initial storage temp
45、eratures.10.1.3 Final Curing:10.1.3.1 CylindersUpon completion of initial curing and within 30 min after removing the molds, cure specimens with freewater maintained on their surfaces at all times at a temperature of 23.0 6 2.0C 73.5 6 3.5F using water storage tanks or moistrooms complying with the
46、requirements of Specification C511, except when capping with sulfur mortar capping compound andimmediately prior to testing. When capping with sulfur mortar capping compound, the ends of the cylinder shall be dry enoughto preclude the formation of steam or foam pockets under or in cap larger than 6
47、mm 14 in. as described in Practice C617/C617M.For a period not to exceed 3 h immediately prior to test, standard curing temperature is not required provided free moisture ismaintained on the cylinders and ambient temperature is between 20 and 30C 68 and 86F .10.1.3.2 BeamsBeams are to be cured the s
48、ame as cylinders (see 10.1.3.1) except that they shall be stored in water saturatedwith calcium hydroxide at 23.0 6 2.0C 73.5 6 3.5F at least 20 h prior to testing. Drying of the surfaces of the beam shall beprevented between removal from water storage and completion of testing.NOTE 8Relatively smal
49、l amounts of surface drying of flexural specimens can induce tensile stresses in the extreme fibers that will markedly reducethe indicated flexural strength.10.2 Field CuringField curing is the curing method used for the specimens made and cured as stated in 4.3.10.2.1 CylindersStore cylinders in or on the structure as near to the point of deposit of the concrete represented as possible.Protect all surfaces of the cylinders from the elements in as near as possible the same way as
