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

1、Designation: C173/C173M 10Standard 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 yea

2、r 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 determi

3、nation 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 SI units areshown in brackets. The values stated in each system

4、 may not beexact equivalents; therefore, each system shall be used inde-pendently of the other. Combining values from the two systemsmay 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 theresp

5、onsibility 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.2)2. R

6、eferenced 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/C143M Tes

7、t 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 Precisi

8、on 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 inside

9、 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, when the

10、 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 a larg

11、er 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 of conso

12、lidation 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 microscopicexamination, if used; time of comparison; environmentalexposure; stage in the delivery, placement and co

13、nsolidationprocesses 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 bowl and a topsection (Fig. 1) conforming to the following requirements:1This test

14、method is under the jurisdiction of ASTM Committee C09 onConcrete and Concrete Aggregates and is the direct responsibility of SubcommitteeC09.60 on Testing Fresh Concrete.Current edition approved Feb. 1, 2010. Published March 2010. Originallyapproved in 1942. Last previous edition approved in 2009 a

15、s C173/C173M09 DOI:10.1520/C0173_C0173M-102Section 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, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of AST

16、MStandards volume information, refer to the standards Document Summary page onthe 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.4.1.1 The bowl and top s

17、ections shall be of sufficientthickness and rigidity to withstand rough field use. Thematerial shall not be attacked by high pH cement paste, deformwhen stored at high temperatures in closed spaces, or becomebrittle or crack at low temperatures. A watertight seal must beobtained when the top section

18、 is attached to the bowl.4.1.2 BowlThe bowl shall have a diameter equal to 1 to1.25 times the height and be constructed with a flange at ornear the top surface. Bowls shall not have a capacity of lessthan 0.075 ft32.0 L.4.1.3 Top SectionThe top section shall have a capacity atleast 20 % larger than

19、the bowl and shall be equipped with aflexible gasket and a device to attach the top section to thebowl. The top section shall be equipped with a transparentscale, graduated in increments not greater than 0.5 % from 0 atthe top to 9 %, or more, of the volume of the bowl. Graduationsshall be accurate

20、to 60.1 % by volume of the bowl. The upperend of the neck shall have a watertight cap that will maintaina watertight seal when the meter is inverted and rolled.4.2 FunnelA funnel with a spout of a size permitting it tobe inserted through the neck of the top section and long enoughto extend to a poin

21、t 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 concrete.4.3 Tamping RodA round, straight steel, high-densitypolyethylene, or other plastic rod of equal or greater abr

22、asionresistance with a58 in. 16 m 6116 in. 2 mm diameter. Thelength of the tamping rod shall be at least 4 in. 100 mmgreater than the depth of the bowl in which rodding is beingperformed, but not greater than 24 in. 600 mm in overalllength (Note 1). The length tolerance for the tamping rod shallbe 6

23、18 in. 4 mm. The rod shall have the tamping end or bothends rounded to a hemispherical tip of the same diameter as therod.NOTE 1A rod length of 16 in. 400 mm to 24 in. 600 mm meets therequirements of the following: Practice C31/C31M, Test Method C138/C138M, Test Method C143/C143M, Test Method C173/C

24、173M, and TestMethod C231.4.4 Strike-off BarA flat, straight steel bar at least18 by34by 12 in. 3 by 20 by 300 mm or a flat, straight high-densitypolyethylene bar, or other plastic of equal or greater abrasionresistance, at least14 by34 by 12 in. 6 by 20 by 300 mm.4.5 Calibrated CupA metal or plasti

25、c cup either having acapacity of or being graduated in increments equal to 1.00 60.04 % of the volume of the bowl of the air meter. Thecalibrated cup is only to be used to add water when theconcrete air content exceeds 9 % or the calibrated range of themeter.4.6 Measuring Vessel for Isopropyl Alcoho

26、lA vessel witha minimum capacity of at least 1 pt 500 mL with graduationsnot larger than 4 oz 100 mL for measuring a quantity ofisopropyl alcohol.4.7 SyringeA rubber syringe having a capacity of at least2 oz 50 mL.4.8 Pouring Vessel for WaterA container of approxi-mately 1 qt 1 L capacity.4.9 Scoopo

27、f 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 bowl.4.10 Isopropyl AlcoholUse 70 % by volume isopropylalcohol (approximately 65 % by weight) (Note 2). Otherfoam-dispersing agents ar

28、e permitted if tests demonstrate thatthe use of the agent does not change the indicated air content,in the amounts being 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 c

29、alculations shall be available in the laboratory.NOTE 2Seventy percent isopropyl alcohol is commonly available asrubbing 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 1.25 6 0.5

30、 lb 600 6 200 g.FIG. 1 Apparatus for Measuring Air Content of Fresh Concrete byVolumetric MethodC173/C173M 1025. Calibration5.1 Calibrate the meter and calibrated cup initially andannually or whenever there is reason to suspect damage ordeformation of the meter or calibrated cup.5.2 Determine the vo

31、lume of the bowl with an accuracy ofat least 0.1 % by determining the mass of water required to fillit at room temperature and dividing it by the density of thewater at the same temperature. Follow the calibration proce-dure outlined in Test Method C29/C29M.5.3 Determine the accuracy of the graduati

32、ons 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 increments of 1.0 % of the volume of thebowl to check accuracy throughout the graduated range of airconte

33、nt. The error at any point throughout the graduated rangeshall not exceed 0.1 % of air.5.4 Determine the volume of the calibrated cup using waterat 70 F 21.1 C by the method outlined in 5.2.Aquick checkcan be made by adding one or more calibrated cups of water tothe assembled apparatus and observing

34、 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 contains coarseaggregate particles that would be retained on a 112-in.37.5-mm sieve, wet sieve a representative

35、sample over a 1-in.25-mm sieve to yield somewhat more than enough material tofill the measuring bowl. The wet sieving procedure is describedin Practice C172. Carry out the wet sieving operation with theminimum practicable disturbance of the mortar. Make noattempt to wipe adhering mortar from coarse

36、aggregate par-ticles retained on the sieve.7. Procedure7.1 Rodding and TappingWet the inside of the bowl anddry it to a damp but not shiny appearance. Using the scoopdescribed in 4.9, fill the bowl with freshly mixed concrete intwo layers of equal depth. While placing the concrete in thebowl, move t

37、he scoop around the perimeter of the bowlopening to ensure an even distribution of the concrete withminimal segregation. Rod each layer 25 times uniformly overthe cross section with the rounded end of the rod. Rod thebottom layer throughout its depth. In rodding this layer, usecare not to damage the

38、 bottom of the bowl. For the upper layer,allow the rod to penetrate through the layer being rodded andinto the layer below approximately 1 in. 25 mm. After eachlayer is rodded, tap the sides of the bowl 10 to 15 times withthe mallet to close any voids left by the tamping rod and torelease any large

39、bubbles of air that may have been trapped.After tapping the final layer, a slight excess of concrete,18 in.3 mm or less, above the rim is acceptable. Add or remove arepresentative sample of concrete if necessary to obtain therequired amount of concrete.7.2 Striking OffAfter rodding and tapping of th

40、e secondlayer, strike off the excess concrete with the strike-off bar untilthe surface is flush with the top of the bowl. Wipe the flange ofthe bowl clean.7.3 Adding Water and AlcoholWet the inside of the topsection of the meter, including the gasket. Attach the topsection to the bowl and insert the

41、 funnel. Add at least 1 pt 0.5L of water followed by the selected amount (Note 3)ofisopropyl alcohol. Record the amount of isopropyl alcoholadded. Continue adding water until it appears in the graduatedneck of the top section (Note 4). Remove the funnel.Adjust theliquid level until the bottom of the

42、 meniscus is level with thezero mark. A rubber syringe is useful for this purpose. Attachand 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 m

43、ade with less than 500lb/yd3300 kg/m3 of cement and air contents less than 4 % may requireless than 0.5 pt 200 mL of alcohol. Some high-cement mixes made withsilica fume that have air contents of 6 % or more may require more than3 pt 1400 mL of alcohol. The amount required will vary with theconcrete

44、 air content, the amount and type of air-entraining admixture, thecement content and cement alkali content, and perhaps other factors.Generally, the amount of alcohol necessary can be established for givenmixture proportions and should not change greatly during the course of ajob.NOTE 4When, if ever

45、, it is necessary to use more than 4 or 4.5 pt 2.0L of isopropyl alcohol, it may be necessary to restrict the amount of wateradded initially to avoid overfilling the meter. However, it is desirable toadd at least some water initially to aid in mixing the alcohol and limit thecontact of the concentra

46、ted alcohol with the top surface of the concrete.7.4 Displacing the Volume of Air in the Concrete SpecimenUsing These Procedures:7.4.1 Free the Concrete from the Base Quickly invert themeter, shake the base horizontally, and return the meter to theupright position. To prevent the aggregate from lodg

47、ing in theneck of the unit, do not keep it inverted for more than 5 s at atime. Repeat the inversion and shaking process for a minimumof 45 s and until the concrete has broken free and the aggregatecan be heard moving in the meter as it is inverted.7.4.2 RollingPlace one hand on the neck of the mete

48、r andthe other on the flange. Using the hand on the neck, tilt the topof the meter approximately 45 from the vertical position withthe bottom edge of the base of the meter resting on the floor oron the work surface. Maintain this position through theprocedures described in this section. Using the ha

49、nd on theflange to rotate the meter, vigorously roll the meter14 to12 turnforward and back several times, quickly starting and stoppingthe roll. Turn the base of the meter about13 turn and repeat therolling procedure as stated previously. Continue the turningTABLE 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 0.75ASubtract from final meter