ASTM_C_31_C31M-21.pdf

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of Intenational Standards,Guides and Recommendations issed by the World Trade Organization Technical Barriers to Trade(TBT)ComDesignation:C31/C31M-21Standard 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 revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision r reapproval.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope*1.7 This international standard was developed in accor-1.1 This practice covers procedures for making and curingdance with internationally recognized principles on standard-cylinder and beam specimens from representative samples ofization established in the Decision on Principles for thefresh concrete for a construction project.Development of International Standards,Guides and Recom-mendations issued by the World Trade Organization Technical1.2 The concrete used to make the molded specimens shallBarriers to Trade(TBT)Committee.be sampled after all on-site adjustments have been made to themixture proportions,including the addition of mix water and2.Referenced Documentsadmixtures.This practice is not intended for making specimens2.1 ASTM Standards:from concrete not having measurable slump or requiring othersizes or shapes of specimens.C125 Terminology Relating to Concrete and Concrete Ag-gregates1.3 This practice is not applicable to lightweight insulatingC138/C138M Test Method for Density(Unit Weight),Yield.concrete or controlled low strength material(CLSM).and Air Content(Gravimetric)of ConcreteNoTE 1-Test Method C495/C495M covers the preparation of speci-C143/C143M Test Method for Slump of Hydraulic-Cementmens and the determination of the compressive strength of lightweightConcreteinsulating concrete.Test Method D4832 covers procedures for theC172/C172M Practice for Sampling Freshly Mixed Con-preparation,curing.transporting and testing of cylindrical test specimenscreteof CLSM.C173/C173M Test Method for Air Content of Freshly Mixed1.4 The values stated in either SI units or inch-pound unitsConcrete by the Volumetric Methodare to be regarded separately as standard.The values stated inC231/C231M Test Method for Air Content of Freshly Mixedeach system may not be exact equivalents;therefore,eachConcrete by the Pressure Methodsystem shall be used independently of the other.CombiningC330/C330M Specification for Lightweight Aggregates forvalues from the two systems may result in non-conformanceStructural Concretewith the standard.C403/C403M Test Method for Time of Setting of Concrete1.5 This standard does not purport to address all of theMixtures by Penetration Resistancesafety concerns,if any,associated with its use.It is theC470/C470M Specification for Molds for Forming Concreteresponsibility of the user of this standard to establish appro-Test Cylinders Verticallypriate safety.health,and environmental practices and deter-C495/C495M Test Method for Compressive Strength ofmine the applicability of regulatory limitations prior to use.Lightweight Insulating Concrete(Warning-Fresh hydraulic cementitious mixtures are causticC511 Specification for Mixing Rooms,Moist Cabinets,and may cause chemical burns to exposed skin and tissue uponMoist Rooms,and Water Storage Tanks Used in theprolonged exposure.)Testing of Hydraulic Cements and Concretes1.6 The text of this standard references notes which provideC617/C617M Practice for Capping Cylindrical Concreteexplanatory material.These notes shall not be considered asSpecimensrequirements of the standard.C1064/C1064M Test Method for Temperature of FreshlyMixed Hydraulic-Cement ConcreteThis practice is under the jurisdiction of ASTM Committee C09 on ConcreteC1077 Practice for Agencies Testing Concrete and Concreteand Concrete Aggregates and is the direct responsibility of Subcommittee C09.61Aggregates for Use in Construction and Criteria foron Testing for Strength.Current edition approved March 1.2021.Published March 2021.Originallyapproved in 1920.Last previous edition approved in 2019a as C31/C31M-19.DOl:For referenced ASTM standards,visit the ASTM website,www.astm.org.or10.1520/C0031_C0031M-21.contact ASTM Customer Service at serviceastm.org.For Annual Book of ASTM2 See Section on Safety Precautions,Manual of Aggregate and Concrete Testing.Standards volume information.refer to the standards Document Summary page onAnnual Book of ASTM Standards,Vol.04.02.the ASTM website*A Summary of Changes section appears at the end of this standardCopyrightASTM Intemational,100 Barr Harbor Drive.PO Box C700.West Conshohocken,PA 19428-2959.United StatesCopyright by ASTM In(all rights reserved):Sun Apr 1102:33:EDT 20211C31/C31M-21Testing Agency EvaluationC470M.A suitable sealant,such as heavy grease,modelingC1611/C1611M Test Method for Slump Flow of Self-clay,or microcrystalline wax shall be used where necessary toConsolidating Concreteprevent leakage through the joints.Positive means shall beC1758/C1758M Practice for Fabricating Test Specimensprovided to hold base plates firmly to the molds.Reusablewith Self-Consolidating Concretemolds shall be lightly coated with mineral oil or a suitableD4832 Test Method for Preparation and Testing of Con-nonreactive form release material before use.trolled Low Strength Material(CLSM)Test Cylinders5.2 Cylinder Molds-Molds for casting concrete test speci-2.2 American Concrete Institute Publication:mens shall conform to the requirements of Specification309R Guide for Consolidation of ConcreteC470/C470M.Cardboard cylinder molds shall not be used for3.Terminologystandard-cured specimens.3.1 For definitions of terms used in this practice,refer to5.3 Beam Molds-Beam molds shall be of the shape anddimensions required to produce the specimens stipulated in 6.2.Terminology C125.The inside surfaces of the molds shall be smooth.The sides.3.2 Definitions of Terms Specific to This Standard:bottom,and ends shall be at right angles to each other and shall3.2.1 initial curing temperature,n-temperature of the en-be straight and true and free of warpage.Maximum variationvironment surrounding the specimen during initial curing.from the nominal cross section shall not exceed 3 mm s in.3.2.1.1 Discussion-The environment surrounding the testfor molds with depth or breadth of 150 mm 6 in.or more.specimens may be air,water,or sand.The temperature of theMolds shall produce specimens at least as long but not moreenvironment surrounding the test specimen might not be thethan 2 mm 6 in.shorter than the required length in 6.2.same as the concrete temperature.5.4 Tamping Rod-A round,smooth,straight,steel rod with4.Significance and Usea diameter conforming to the requirements in Table 1.Thelength of the tamping rod shall be at least 100 mm 4 in.4.1 This practice provides standardized requirements forgreater than the depth of the mold in which rodding is beingmaking,curing,protecting,and transporting concrete testperformed,but not greater than 600 mm 24 in.in overallspecimens under field conditions.length(see Note 2).The rod shall have the tamping end or both4.2 If the specimens are made and standard cured,asends rounded to a hemispherical tip of the same diameter as thestipulated herein,the resulting strength test data when therod.specimens are tested are able to be used for the followingNorE 2-A rod length of 400 mm 16 in.to 600 mm 24 in.meets thepurposes:requirements of the following:Practice C31/C31M.Test Method C138/4.2.1 Acceptance testing for specified strength,C138M.Test Method C143/C143M.Test Method C173/C173M.and TestMethod C231/C231M.4.2.2 Checking adequacy of mixture proportions forstrength,and5.5 Vibrators-Internal vibrators shall be used.The vibrator4.2.3 Quality controlfrequency shall be at least 150 Hz 9000 vibrations per minutewhile the vibrator is operating in the concrete.The diameter of4.3 If the specimens are made and field cured,as stipulateda round vibrator shall be no more than one-fourth the diameterherein,the resulting strength test data when the specimens areof the cylinder mold or one-fourth the width of the beam mold.tested are able to be used for the following purposes:Other shaped vibrators shall have a perimeter equivalent to the4.3.1 Determination of whether a structure is capable ofcircumference of an appropriate round vibrator.The combinedbeing put in service,length of the vibrator shaft and vibrating element shall exceed4.3.2 Comparison with test results of standard cured speci-the depth of the section being vibrated by at least 75 mm 3mens or with test results from various in-place test methods,in.The vibrator frequency shall be checked periodically with4.3.3 Adequacy of curing and protection of concrete in thea vibrating-reed tachometer or other suitable device.structure,or4.3.4 Form or shoring removal time requirementsNorE 3-For information on size and frequency of various vibratorsand a method to periodically check vibrator frequency see ACI 309R.5.Apparatus5.6 Mallet-A mallet with a rubber or rawhide head weigh-5.1 Molds,General-Molds for specimens or fasteningsing 0.6 kg+0.2 kg 1.25 Ib+0.50 Ibshall be usedthereto in contact with the concrete shall be made of steel,cast5.7 Placement Tools-of a size large enough so each amountiron,or other nonabsorbent material,nonreactive with concreteof concrete obtained from the sampling receptacle is represen-containing portland or other hydraulic cements.Molds shalltative and small enough so concrete is not spilled duringhold their dimensions and shape under all conditions of use.placement in the mold.For placing concrete in a cylinder moldMolds shall be watertight during use as judged by their abilityto hold water poured into them.Provisions for tests of waterTABLE 1 Tamping Rod Diameter Requirementsleakage are given in the Test Methods for Elongation,Diameter of CylindeAbsorption,and Water Leakage section of Specification C470/Diameter or Rodor Width of Beammm in.mm in.2003 or more equal depthssee 9.3from Table 5.Select a scoop of the size described in 5.7.Whileeach not to exceedplacing the concrete in the mold,move the scoop around the150 mm 6 in.perimeter of the mold opening to ensure an even distribution ofthe concrete with minimal segregation.Each layer of concreteshall be consolidated as required.In placing the final layer,addTABLE 5 Molding Requirements by Vibrationan amount of concrete that will fill the mold after consolida-Number ofSpecimen TypeNumber ofVibratorApproximate Depth oftion.and SizeLayersInsertionsLayer,mmn】9.2.1 Self-Consolidating Concrete-If casting cylinders ofper Layerself-consolidating concrete,use the mold filling procedures inCylinders:Practice C1758/C1758M instead of the procedure in 9.2.AfterDiameter,mm in.1004one-half depth of specimenfilling the mold,finish the cylinders in accordance with 9.5.15063one-halt depth of specimenwithout further consolidation.2259】one-half depth of specimen9.3 Casting Beams-Select the proper tamping rod from 5.4Beams:and Table 1 or proper vibrator from 5.5.Determine the methodWidth,mm in.1004to1see9.4.2depth of specimenof consolidation from Table 3,unless another method is20081specified.If the method of consolidation is rodding,determineover 200 82 or moresee9.4.2200 8as near asthe molding requirements from Table 4.If the method ofpracticableconsolidation is vibration,determine the molding requirementsfrom Table 5.Determine the number of roddings per layer,onefor each 14 cm2 in.of the top surface area of the beam.Select a placement tool as described in 5.7.Using the scoop orand into the layer below approximately 25 mm 1 in.Aftershovel,place the concrete in the mold to the height required foreach layer is rodded,tap the outsides of the mold lightly 10 toeach layer.Place the concrete so that it is uniformly distributed15 times with the mallet to close any holes left by rodding andwithin each layer with minimal segregation.Each layer shall beto release any large air bubbles that may have been trappedconsolidated as required.In placing the final layer,add anUse an open hand to tap cylinder molds that are susceptible toamount of concrete that will fill the mold after consolidationdenting or other permanent distortion if tapped with a mallet.9.3.1 Self-Consolidating Concrete-If casting beams ofAfter tapping,spade each layer of the concrete along the sidesself-consolidating concrete,use the mold filling procedures inand ends of beam molds with a trowel or other suitable tool.Practice C1758/C1758M instead of the procedure in 9.3.AfterUnderfilled molds shall be adjusted with representative con-filling the mold,finish the beams in accordance with 9.5.crete during consolidation of the top layer.Overfilled moldswithout further consolidation.shall have excess concrete removed.9.4.2 Vibration-Maintain a uniform duration of vibration9.4 Consolidation-The methods of consolidation for thisfor the particular kind of concrete,vibrator,and specimen moldpractice are rodding or internal vibration.9.4.1 Rodding-Place the concrete in the mold in theinvolved.The duration of vibration required will depend uponthe workability of the concrete and the effectiveness of therequired number of layers of approximately equal volume.Rodeach layer uniformly over the cross section with the roundedvibrator.Usually sufficient vibration has been applied as soonas the surface of the concrete has become relatively smooth andend of the rod using the required number of strokes.Rod thelarge air bubbles cease to break through the top surface.bottom layer throughout its depth.In rodding this layer,usecare not to damage the bottom of the mold.For each upperContinue vibration only long enough to achieve proper con-layer,allow the rod to penetrate through the layer being roddedsolidation of the concrete(see Note 7).Fill the molds andvibrate in the required number of approximately equal layers.Place all the concrete for each layer in the mold before startingTABLE 3 Method of Consolidation Requirementsvibration of that layer.In compacting the specimen,insert thevibrator slowly and do not allow it to rest on the bottom orSlump.mm in.Method of Consolidationsides of the mold.Slowly withdraw the vibrator so that no large251刊rodding or vibration25I1vibrationair pockets are left in the specimen.When placing the finallayer,avoid overfilling by more than 6 mm 4 in.Copyright by ASTM Int(all rights reserved):Sun Apr 1102:33:EDT 202144C31/C31M-21NorE 7-Generally,no more than 5 s of vibration should be required forwithout proper support.Using a large trowel or a hand to support theeach insertion to adequately consolidate concrete with a slump greaterbottom of these molds are acceptable means to prevent permanentthan 75 mm 3 in.Longer times may be required for lower slumpdeformation.It is acceptable to slightly tilt the mold to facilitate lifting andconcrete.but the vibration time should rarely have to exceed 10 s persupporting the mold.If a cover is to be placed on the top of a specimen,insertion.the cover should be placed on the specimen after moving the specimen to9.4.2.1 Cylinders-The number of insertions of the vibratorthe initial curing location to ensure the required finish of the top surfaceper layer is given in Table 5.When more than one insertion perof the specimen.For example,if a specimen will be stored in water forinitial curing,it would be appropriate to perform a final check of thelayer is required distribute the insertion uniformly within eachsurface finish prior to placing the cover and setting the specimen into thelayer.Allow the vibrator to penetrate through the layer beingwater.vibrated,and into the layer below,about 25 mm 1 in.Aftereach layer is vibrated,tap the outsides of the mold at least 1010.1.2 Initial Curing-Store standard-cured specimens for atimes with the mallet,to close holes that remain and to releaseperiod up to 48 h after molding to maintain the specifiedentrapped air voids.Use an open hand to tap molds that aretemperature and moisture conditions described in 10.1.2.1 andsusceptible to denting or other permanent distortion if tapped10.1.2.2with a mallet.NorE 9-Generally,just covering the specimens is not sufficient to9.4.2.2 Beams-Insert the vibrator at intervals not exceed-maintain the environment required for initial standard curing.ing 150 mm 6 in.along the center line of the long dimensionof the specimen.For specimens wider than 150 mm 6 in.,use10.1.2.1 For concrete mixtures with a specified strength lessalternating insertions along two lines.Allow the shaft of thethan 40 MPa 6000 psi,maintain the initial curing temperaturevibrator to penetrate into the bottom layer about 25 mm I in.between 16C and 27C 60F and 80F.For concreteAfter each layer is vibrated,tap the outsides of the moldmixtures with a specified strength of 40 MPa 6000 psiorsharply at least 10 times with the mallet to close holes left bygreater,maintain the initial curing temperature between 20Cvibrating and to release entrapped air voids.and 26C 68 F and 78 F.Shield specimens from directexposure to sunlight and,if used,radiant heating devices9.5 Finishing-Perform all finishing with the minimumRecord the minimum temperature and maximum temperaturesmanipulation necessary to produce a flat even surface that isachieved for each set of specimens during the initial curinglevel with the rim or edge of the mold and that has noperiod.depressions or projections larger than 3.3 mm s in.9.5.1 Cylinders-After consolidation,finish the top surfacesNoTE 10-A satisfactory temperature environment can be createdby striking them off with the tamping rod where the consis-during the initial curing of the specimens by one or more of the followingtency of the concrete permits or with a handheld float or trowel.procedures:(1)use of ventilation:(2)use of ice;(3)use of coolingIf desired,cap the top surface of freshly made cylinders with adevices;or(4)use of heating devices such as electrical resistance heatersthin layer of stiff portland cement paste which is permitted toor light bulbs.Other suitable methods may be used provided thetemperature requirements are met.harden and cure with the specimen.See section on CappingNorE 11-Early-age strength test results may be lower if specimens areMaterials of Practice C617/C617M.stored at temperatures lower than the specified range.At later ages,9.5.2 Beams-After consolidation of the concrete,use astrength test results may be lower if specimens are exposed to initialhandheld float or trowel to strike off the top surface to thecuring temperatures higher than the specified range.required tolerance to produce a flat,even surface10.1.2.2 Store the specimens in an environment that con-9.6 Identification-Mark the specimens to positively iden-trols the loss of moisture.tify them and the concrete they represent.Use a method thatwill not alter the top surface of the concrete.Do not mark theNore 12-A satisfactory moisture environment can be created duringremovable caps.Upon removal of the molds,mark the testthe initial curing of the specimens by one or more of the followingspecimens to retain their identities.procedures:(1)immerse molded specimens with plastic lids in water:(2)store specimens in a container or enclosure;(3)place specimens in dampsand pits:(4)cover specimens with plastic lids;(5)place specimens inside10.Curingplastic bags;or(6)cover specimens with wet fabric.10.1 Standard Curing-Standard curing is the curingNorE 13-Immersion in water may be the easiest method to maintainmethod used when the specimens are made and cured for therequired moisture and temperature conditions during initial curing.purposes stated in 4.2.10.1.3 Final Curing:10.1.1 Storage-The supporting surface on which speci-10.1.3.1 Cylinders-Upon completion of initial curing andmens are stored shall be level to within 20 mm/m V4 in./ft.Ifwithin 30 min after removing the molds,cure specimens withspecimens are not molded in the location where they willfree water maintained on their surfaces at all times at areceive initial curing,ensure that the specimens have beentemperature of23.0C2.0C73.53.5 Fusing wa-moved to the initial curing location no later than 15 min afterter storage tanks or moist rooms complying with the require-molding operations have been completed.If a specimen in aments of Specification C511,except when capping with sulfursingle-use mold is moved,support the bottom of the mold.Ifmortar capping compound and immediately prior to testingthe top surface of a specimen is disturbed during movement toWhen capping with sulfur mortar capping compound,the endsthe place of initial storage,refinish the surface.of the cylinder shall be dry enough to preclude the formation ofNorE 8-Some single-use molds.such as cylinder molds constructed ofsteam or foam pockets under or in cap larger than 6 mm 4 in.sheet metal or treated cardboard,may be permanently distorted if movedas described in Practice C617/C617M.For a period not toCopyright by ASTM Inl(all rights reserved):Sun Apr 1102:33:39 EDT 20215