ASTM C173 C173M-2009 Standard Test Method for Air Content of Freshly Mixed Concrete by the Volumetric Method.pdf

1、Designation: C 173/C 173M 09Standard Test Method forAir Content of Freshly Mixed Concrete by the VolumetricMethod1This standard is issued under the fixed designation C 173/C 173M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the

2、 year 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 det

3、ermination 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 sy

4、stem 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 the

5、responsibility 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)

6、2. Referenced Documents2.1 ASTM Standards:3C 29/C 29M Test Method for Bulk Density (“Unit Weight”)and Voids in AggregateC 172 Practice for Sampling Freshly Mixed ConcreteC 231 Test Method for Air Content of Freshly MixedConcrete by the Pressure MethodC 670 Practice for Preparing Precision and Bias S

7、tatementsfor 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 porous aggre

8、gate 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 meter is ini

9、tially 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 larger quantity o

10、f 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 consolidation effo

11、rtapplied 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 consolidationpr

12、ocesses 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:4.1.1 The bowl and top s

13、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

14、 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.1This test method is under the jurisdiction of ASTM Committee C09 onConcrete and

15、 Concrete Aggregates and is the direct responsibility of SubcommitteeC09.60 on Testing Fresh Concrete.Current edition approved June 1, 2009. Published July 2009. Originally approvedin 1942. Last previous edition approved in 2008 as C 173/C 173M 08a.2Section on Safety Precautions, Manual of Aggregate

16、 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 onthe ASTM websit

17、e.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.4.1.3 Top SectionThe top section shall have a capacity atleast 20 % larger than the bowl and shall be equipped with a

18、flexible 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 to 60.1 % by volume of the bowl. The

19、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 point just above the bottom of the top se

20、ction.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, smooth, straight58 6116-in.16 6 2-mm diameter rod at least 12 in. 300 mm long withboth ends rounded to a hemispherical tip

21、of the same diameter.The rod shall be made of steel, high-density polyethylene, orother plastic of equal or greater abrasion resistance.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

22、or greater abrasionresistance, at least14 by34 by 12 in. 6 by 20 by 300 mm.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 bowl of the air meter. Thecalibrated cup is only to be used to add water when the

23、concrete air content exceeds 9 % or the calibrated range of themeter.4.6 Measuring Vessel for Isopropyl AlcoholA 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 capacit

24、y of at least2 oz 50 mL.4.8 Pouring Vessel for WaterA container of approxi-mately 1 qt 1 L 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 bowl.4.10 Isopropyl Alco

25、holUse 70 % by volume isopropylalcohol (approximately 65 % by weight) (Note 1). Otherfoam-dispersing agents are 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 simila

26、r 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 1Seventy percent isopropyl alcohol is commonly available asrubbing alcohol. More concentrated grades can be diluted with water tothe req

27、uired concentration.4.11 MalletA mallet (with a rubber or rawhide head) witha mass of approximately 1.25 6 0.5 lb 600 6 200 g.5. 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

28、Determine the volume 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 theFIG. 1 Apparatus for Measuring Air Content of Fresh Concrete byVolumetric MethodTABLE 1 Correction for the Effect of Isoprop

29、yl Alcohol onC 173/C 173M 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 reading.BCorrections are applied only when 2.5 pt 1.25 L or more of isopropyl alcoholis used. The v

30、alues given are for air meters that have a bowl volume of 0.075 ft32.1 L and a top section that is 1.2 times the volume of the bowl.C 173/C 173M 092water at the same temperature. Follow the calibration proce-dure outlined in Test Method C 29/C 29M.5.3 Determine the accuracy of the graduations on the

31、 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 aircontent. The er

32、ror 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 the incre

33、ase 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 C 172. If the concrete contains coarseaggregate particles that would be retained on a 112-in.37.5-mm sieve, wet sieve a representative sample ov

34、er a 1-in.25-mm sieve to yield somewhat more than enough material tofill the measuring bowl. The wet sieving procedure is describedin Practice C 172. Carry out the wet sieving operation with theminimum practicable disturbance of the mortar. Make noattempt to wipe adhering mortar from coarse aggregat

35、e 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 the scoop

36、 around the perimeter of the bowlopening to ensure an even distribution of the concrete withminimal segregation. Rod each layer 25 times with the tampingrod. Do not forcibly strike the bottom of the bowl whenrodding the first layer. When rodding the second layer, pen-etrate the prior layer about 1 i

37、n. 25 mm. After each layer isrodded, tap the sides of the bowl 10 to 15 times with the malletto close any voids left by the tamping rod and to release anylarge bubbles of air that may have been trapped. After tappingthe final layer, a slight excess of concrete,18 in. 3 mm or less,above the rim is ac

38、ceptable. Add or remove a representativesample of concrete if necessary to obtain the required amountof 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 bowl. Wipe the flange of

39、the 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 funnel. Add at least 1 pt 0.5L of water followed by the selected amount (Note 2)ofisopropyl alcohol. Record the amount of isopropyl alcohol

40、added. Continue adding water until it appears in the graduatedneck of the top section (Note 3). Remove the funnel.Adjust theliquid level until the bottom of the meniscus is level with thezero mark. A rubber syringe is useful for this purpose. Attachand tighten the watertight cap.NOTE 2The amount of

41、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 500lb/yd3300 kg/m3 of cement and air contents less than 4 % may requireless than 0.5 pt 200 mL of alcohol. Some high-ceme

42、nt 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 air content, the amount and type of air-entraining admixture, thecement content and cement alkali content, and perhaps other factors.Genera

43、lly, the amount of alcohol necessary can be established for givenmixture proportions and should not change greatly during the course of ajob.NOTE 3When, if ever, 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

44、 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 concentrated 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

45、the Concrete from the Base Quickly invert themeter, shake the base horizontally, and return the meter to theupright position. To prevent the aggregate from lodging 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

46、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 meter andthe other on the flange. Using the hand on the neck, tilt the topof the meter approximately 45 from the vertical position withthe botto

47、m 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 hand on theflange to rotate the meter, vigorously roll the meter14 to12 turnforward and back several times, quickly starting and stoppingthe r

48、oll. Turn the base of the meter about13 turn and repeat therolling procedure as stated previously. Continue the turningand rolling procedures for approximately 1 min. The aggregatemust be heard sliding in the meter during this process.7.4.2.1 If, at any time, during the inversion and rollingprocedur

49、es liquid is found to be leaking from the meter, the testis invalid and a new test shall be started as in 6.1.7.4.2.2 Set the unit upright and loosen the top to allow anypressure to stabilize. Allow the meter to stand while the airrises to the top and until the liquid level stabilizes. The liquidlevel is considered stable when it does not change more than0.25 % air within a 2-min period.7.4.2.3 If it takes more than 6 min for the liquid level tostabilize or if there is more foam than that equivalent to 2