ASTM C173 C173M-2010b Standard Test Method for Air Content of Freshly Mixed Concrete by the Volumetric Method《体积法测定新拌混凝土的含气量的标准试验方法》.pdf

1、Designation: C173/C173M 10bStandard Test Method forAir Content of Freshly Mixed Concrete by the VolumetricMethod1This standard is issued under the fixed designation C173/C173M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the ye

2、ar of last revision. A number in parentheses indicates the year of last reapproval.A superscript 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 test method covers determ

3、ination of the air contentof freshly mixed concrete containing any type of aggregate,whether it be dense, cellular, or lightweight.1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The inch-pound unitsare shown in brackets. The values stated in ea

4、ch system maynot be exact equivalents; therefore, each system shall be usedindependently of the other. Combining values from the twosystems may result in non-conformance with the standard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is

5、theresponsibility of the user of 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 skin and tissue upon prolonged exposure

6、.2)2. Referenced Documents2.1 ASTM Standards:3C29/C29M Test Method for Bulk Density (“Unit Weight”)and Voids in AggregateC31/C31M Practice for Making and Curing Concrete TestSpecimens in the FieldC138/C138M Test Method for Density (Unit Weight),Yield, and Air Content (Gravimetric) of ConcreteC143/C1

7、43M 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 Pressure MethodC670 Practice for Preparing

8、Precision and Bias Statementsfor Test Methods for Construction Materials3. Significance and Use3.1 This test method covers the determination of the aircontent of freshly mixed concrete. It measures the air containedin the mortar fraction of the concrete, but is not affected by airthat may be present

9、 inside porous aggregate particles.3.1.1 Therefore, this is the appropriate test to determine theair content of concretes containing lightweight aggregates,air-cooled slag, and highly porous or vesicular natural aggre-gates.3.2 This test method requires the addition of sufficientisopropyl alcohol, w

10、hen the meter is initially being filled withwater, so that after the first or subsequent rollings little or nofoam collects in the neck of the top section of the meter. Ifmore foam is present than that equivalent to 2 % air above thewater level, the test is declared invalid and must be repeatedusing

11、 a larger quantity of alcohol. Addition of alcohol to dispelfoam any time after the initial filling of the meter to the zeromark is not permitted.3.3 The air content of hardened concrete may be eitherhigher or lower than that determined by this test method. Thisdepends upon the methods and amounts o

12、f consolidation effortapplied to the concrete from which the hardened concretespecimen is taken; uniformity and stability of the air bubbles inthe fresh and hardened concrete; accuracy of the microscopic1This test method is under the jurisdiction of ASTM Committee C09 onConcrete and Concrete Aggrega

13、tes and is the direct responsibility of SubcommitteeC09.60 on Testing Fresh Concrete.Current edition approved Oct. 1, 2010. Published November 2010. Originallyapproved in 1942. Last previous edition approved in 2010 as C173/C173M10a.DOI: 10.1520/C0173_C0173M-10b.2Section on Safety Precautions, Manua

14、l 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.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page ont

15、he ASTM website.1*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.examination, if used; time of comparison; environmentalexposure; stage in the delivery, placement and c

16、onsolidationprocesses at which the air content of the unhardened concreteis determined, that is, before or after the concrete goes througha pump; and other factors.4. Apparatus4.1 Air MeterAn air meter consisting of a measuring bowland a top section (Fig. 1) conforming to the followingrequirements:4

17、.1.1 The measuring bowl and top sections shall be ofsufficient thickness and rigidity to withstand rough field use.The material shall not be attacked by high pH cement paste,deform when stored at high temperatures in closed spaces, orbecome brittle or crack at low temperatures. A watertight sealmust

18、 be obtained when the top section is attached to themeasuring bowl.4.1.2 Measuring BowlThe measuring bowl shall have adiameter equal to 1 to 1.25 times the height and be constructedwith a flange at or near the top surface. Measuring bowls shallnot have a capacity of less than 2.0 L 0.075 ft3.4.1.3 T

19、op SectionThe top section shall have a capacity atleast 20 % larger than the measuring bowl and shall beequipped with a flexible gasket and a device to attach the topsection to the measuring bowl. The top section shall beequipped with a transparent scale, graduated in increments notgreater than 0.5

20、% from 0 at the top to 9 %, or more, of thevolume of the measuring bowl. Graduations shall be accurateto 60.1 % by volume of the measuring bowl. The upper end ofthe neck shall have a watertight cap that will maintain awatertight seal when the meter is inverted and rolled.4.2 FunnelA funnel with a sp

21、out of a size permitting it tobe inserted through the neck of the top section and long enoughto extend to a point just above the bottom of the top section.The discharge end of the spout shall be so constructed thatwhen water is added to the container there will be a minimumdisturbance of the concret

22、e.4.3 Tamping RodA round, smooth, straight steel, high-density polyethylene, or other plastic rod of equal or greaterabrasion resistance with a 16 m 58 in. 6 2mm116 in.diameter. The length of the tamping rod shall be at least 100mm 4 in. greater than the depth of the measuring bowl inwhich rodding i

23、s being performed, but not greater than 600 mm24 in. in overall length (Note 1). The rod shall have thetamping end or both ends rounded to a hemispherical tip of thesame diameter as the rod.NOTE 1A rod length of 400 mm 16 in. to 600 mm 24 in. meets therequirements of the following: Practice C31/C31M

24、, Test Method C138/C138M, Test Method C143/C143M, Test Method C173/C173M, and TestMethod C231.4.4 Strike-off BarA flat, straight steel bar at least 3 by 20by 300 mm 18 by34 by 12 in. or a flat, straight high-densitypolyethylene bar, or other plastic of equal or greater abrasionresistance, at least 6

25、 by 20 by 300 mm 14 by34 by 12 in.4.5 Calibrated CupA metal or plastic cup either having acapacity of or being graduated in increments equal to 1.00 60.04 % of the volume of the measuring bowl of the air meter.The calibrated cup is only to be used to add water when theconcrete air content exceeds 9

26、% or the calibrated range of themeter.4.6 Measuring Vessel for Isopropyl AlcoholA vessel witha minimum capacity of at least 500 mL 1 pt with graduationsnot larger than 100 mL 4 oz for measuring a quantity ofisopropyl alcohol.4.7 SyringeA rubber syringe having a capacity of at least50 mL 2 oz.4.8 Pou

27、ring Vessel for WaterA container of approxi-mately 1 L 1 qt capacity.4.9 Scoopof a size large enough so each amount ofconcrete obtained from the sampling receptacle is representa-tive and small enough so it is not spilled during placement inthe measuring bowl.4.10 Isopropyl AlcoholUse 70 % by volume

28、 isopropylalcohol (approximately 65 % by weight) (Note 2). Otherfoam-dispersing agents are permitted if tests demonstrate thatFIG. 1 Apparatus for Measuring Air Content of Fresh Concrete byVolumetric MethodC173/C173M 10b2the use of the agent does not change the indicated air content,in the amounts b

29、eing used, by more than 0.1 % or if correctionfactors are developed similar to those in Table 1. When otherdispersing agents are used, a copy of the records documentingthe testing or calculations shall be available in the laboratory.NOTE 2Seventy percent isopropyl alcohol is commonly available asrub

30、bing alcohol. More concentrated grades can be diluted with water tothe required concentration.4.11 MalletA mallet (with a rubber or rawhide head) witha mass of approximately 600 6 200 g 1.25 6 0.5 lb.5. Calibration5.1 Calibrate the meter and calibrated cup initially andannually or whenever there is

31、reason to suspect damage ordeformation of the meter or calibrated cup.5.2 Determine the volume of the measuring bowl with anaccuracy of at least 0.1 % by determining the mass of waterrequired to fill it at room temperature and dividing it by thedensity of the water at the same temperature. Follow th

32、ecalibration procedure outlined in Test Method C29/C29M.5.3 Determine the accuracy of the graduations on the neckof the top section of the air meter by filling the assembledmeasuring bowl and top section with water to the level of themark for highest air content graduation.5.3.1 Add water in increme

33、nts of 1.0 % of the volume of themeasuring bowl to check accuracy throughout the graduatedrange of air content. The error at any point throughout thegraduated range shall not exceed 0.1 % of air.5.4 Determine the volume of the calibrated cup using waterat 21.1 C 70 F by the method outlined in 5.2.Aq

34、uick checkcan be made by adding one or more calibrated cups of water tothe assembled apparatus and observing the increase in theheight of the water column after filling to a given level.6. Sampling6.1 Obtain the sample of freshly mixed concrete in accor-dance with Practice C172. If the concrete cont

35、ains coarseaggregate particles that would be retained on a 37.5-mm112-in. sieve, wet sieve a representative sample over a 25-mm1-in. sieve to yield somewhat more than enough material tofill the measuring bowl. The wet sieving procedure is describedin Practice C172.6.2 The concrete used to fill the m

36、easuring bowl shall nothave been previously used in the performance of any other testor practice, other than wet sieving or the temperature test.7. Procedure7.1 Rodding and TappingWet the inside of the measuringbowl and dry it to a damp but not shiny appearance. Using thescoop described in 4.9, fill

37、 the measuring bowl with freshlymixed concrete in two layers of approximately equal volume.While placing the concrete in the measuring bowl, move thescoop around the perimeter of the measuring bowl opening toensure an even distribution of the concrete with minimalsegregation. Rod each layer 25 times

38、 uniformly over the crosssection with the rounded end of the rod. Rod the bottom layerthroughout its depth. In rodding this layer, use care not todamage the bottom of the measuring bowl. For the upper layer,allow the rod to penetrate through the layer being rodded andinto the layer below approximate

39、ly 25 mm 1 in. After eachlayer is rodded, tap the sides of the measuring bowl 10 to 15times with the mallet to close any voids left by the tamping rodand to release any large bubbles of air that may have beentrapped. After tapping the final layer, a slight excess ofconcrete, 3 mm 18 in. or less, abo

40、ve the rim is acceptable.Add or remove a representative sample of concrete if necessaryto obtain the required amount of concrete.7.2 Striking OffAfter rodding and tapping of the secondlayer, strike off the excess concrete with the strike-off bar untilthe surface is flush with the top of the measurin

41、g bowl. Wipethe flange of the measuring bowl clean.7.3 Adding Water and AlcoholWet the inside of the topsection of the meter, including the gasket. Attach the topsection to the measuring bowl and insert the funnel. Add atleast 0.5 L 1 pt of water followed by the selected amount(Note 3) of isopropyl

42、alcohol. Record the amount of isopropylalcohol added. Continue adding water until it appears in thegraduated neck of the top section (Note 4). Remove the funnel.Adjust the liquid level until the bottom of the meniscus is levelwith the zero mark. A rubber syringe is useful for this purpose.Attach and

43、 tighten the watertight cap.NOTE 3The amount of isopropyl alcohol necessary to obtain a stablereading and a minimum of foam at the top of the water column willdepend upon a number of factors. Many concretes made with less than 300kg/m3500 lb/yd3 of cement and air contents less than 4 % may requirele

44、ss than 0.2 L 0.5 pt of alcohol. Some high-cement mixes made withsilica fume that have air contents of 6 % or more may require more than1.4 L 3 pt of alcohol. The amount required will vary with the concreteair content, the amount and type of air-entraining admixture, the cementcontent and cement alk

45、ali content, and perhaps other factors. Generally,the amount of alcohol necessary can be established for given mixtureproportions and should not change greatly during the course of a job.NOTE 4When, if ever, it is necessary to use more than 2.0 L 4 or 4.5pt of isopropyl alcohol, it may be necessary

46、to restrict the amount ofwater added initially to avoid overfilling the meter. However, it isdesirable to add at least some water initially to aid in mixing the alcoholand limit the contact of the concentrated alcohol with the top surface of theconcrete.7.4 Displacing the Volume of Air in the Concre

47、te SpecimenUsing These Procedures:7.4.1 Free the Concrete from the Measuring BowlQuickly invert the meter, shake the measuring bowl horizon-tally, and return the meter to the upright position. To preventthe aggregate from lodging in the neck of the unit, do not keepit inverted for more than5satatime

48、. Repeat the inversion andshaking process for a minimum of 45 s and until the concreteTABLE 1 Correction for the Effect of Isopropyl Alcohol onC173/C173M Air Meter Reading70 % Isopropyl Alcohol UsedPints FluidOuncesLitres Correction, %A# 2.0 # 32 # 1.0 0.0B3.0 48 1.5 0.254.0 64 2.0 0.505.0 80 2.5 0.

49、75ASubtract from final meter reading.BCorrections are applied only when 1.25 L 2.5 pt or more of isopropyl alcoholis used. The values given are for air meters that have a measuring bowl volume of2.1 L0.075 ft3 and a top section that is 1.2 times the volume of the meauring bowl.C173/C173M 10b3has broken free and the aggregate can be heard moving in themeter as it is inverted.7.4.2 RollingPlace one hand on the neck of the meter andthe other on the flange. Using the hand on the neck, tilt the topof