ASTM C173 C173M-2016 Standard Test Method for Air Content of Freshly Mixed Concrete by the Volumetric Method《采用容积法测定新拌混凝土含气量的标准试验方法》.pdf

1、Designation: C173/C173M 14C173/C173M 16Standard 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 revi

2、sion, the 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 U.S. Department of Defense.1. Scope*1.1 This test met

3、hod covers determination of the air content of freshly mixed concrete containing any type of aggregate, whetherit be dense, cellular, or lightweight.1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The inch-pound units areshown in brackets. The

4、values stated in each system may not be exact equivalents; therefore, each system shall be usedindependently of the other. Combining values from the two systems may result in non-conformance with the standard.1.3 This standard does not purport to address all of the safety concerns, if any, associate

5、d with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use. (WarningFresh hydraulic cementitious mixtures are caustic and may cause chemical burns to skin andtissue up

6、on prolonged exposure.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 Test Specimens in the FieldC138/C138M Test Method for Density (Unit Weight), Yield, and Air Content (Gravime

7、tric) of ConcreteC143/C143M Test Method for Slump of Hydraulic-Cement ConcreteC172 Practice for Sampling Freshly Mixed ConcreteC173/C173M Test Method for Air Content of Freshly Mixed Concrete by the Volumetric MethodC231 Test Method for Air Content of Freshly Mixed Concrete by the Pressure MethodC67

8、0 Practice for Preparing Precision and Bias Statements for Test Methods for Construction MaterialsC1064/C1064M Test Method for Temperature of Freshly Mixed Hydraulic-Cement Concrete3. Significance and Use3.1 This test method covers the determination of the air content of freshly mixed concrete. It m

9、easures the air contained in themortar fraction of the concrete, but is not affected by air that may be present inside porous aggregate particles.3.1.1 Therefore, this is the appropriate test to determine the air content of concretes containing lightweight aggregates,air-cooled slag, and highly poro

10、us or vesicular natural aggregates.3.2 This test method requires the addition of sufficient isopropyl alcohol, when the meter is initially being filled with water, sothat after the first or subsequent rollings little or no foam collects in the neck of the top section of the meter. If more foam is pr

11、esentthan that equivalent to 2 % air above the water level, the test is declared invalid and must be repeated using a larger quantity ofalcohol. Addition of alcohol to dispel foam any time after the initial filling of the meter to the zero mark is not permitted.1 This test method is under the jurisd

12、iction of ASTM Committee C09 on Concrete and Concrete Aggregates and is the direct responsibility of Subcommittee C09.60 onTesting Fresh Concrete.Current edition approved Jan. 1, 2014Feb. 1, 2016. Published February 2014March 2016. Originally approved in 1942. Last previous edition approved in 20122

13、014 asC173/C173M 12.14. DOI: 10.1520/C0173_C0173M-14.10.1520/C0173_C0173M-16.2 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, www.astm.org, or contactASTM Customer Service at ser

14、viceastm.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 what changes have been made to the previous version.

15、 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 the official document.*A Summary of Changes section

16、appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.3 The air content of hardened concrete may be either higher or lower than that determined by this test method. This dependsupon the methods and amoun

17、ts of consolidation effort applied to the concrete from which the hardened concrete specimen is taken;uniformity and stability of the air bubbles in the fresh and hardened concrete; accuracy of the microscopic examination, if used;time of comparison; environmental exposure; stage in the delivery, pl

18、acement and consolidation processes at which the air contentof the unhardened concrete is determined, that is, before or after the concrete goes through a pump; and other factors.4. Apparatus4.1 Air MeterAn air meter consisting of a measuring bowl and a top section (Fig. 1) conforming to the followi

19、ngrequirements:4.1.1 The measuring bowl and top sections shall be of sufficient thickness and rigidity to withstand rough field use. The materialshall not be attacked by high pH cement paste, deform when stored at high temperatures in closed spaces, or become brittle or crackat low temperatures. A w

20、atertight seal must be obtained when the top section is attached to the measuring bowl.4.1.2 Measuring BowlThe measuring bowl shall have a diameter equal to 1 to 1.25 times the height and be constructed witha flange at or near the top surface. Measuring bowls shall not have a capacity of less than 2

21、.0 L 0.075 ft3.4.1.3 Top SectionThe top section shall have a capacity at least 20 % larger than the measuring bowl and shall be equippedwith a flexible gasket and a device to attach the top section to the measuring bowl. The top section shall be equipped with atransparent scale, graduated in increme

22、nts not greater than 0.5 % from 0 at the top to 9 %, or more, of the volume of the measuringbowl. Graduations shall be accurate to60.1 % by volume of the measuring bowl. The upper end of the neck shall have a watertightcap that will maintain a watertight seal when the meter is inverted and rolled.4.

23、2 FunnelA funnel with a spout of a size permitting it to be 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 that when wateris added to the container there will be a minim

24、um disturbance of the concrete.FIG. 1 Apparatus for Measuring Air Content of Fresh Concrete by Volumetric Method (a) Brass MeterC173/C173M 1624.3 Tamping RodA round, smooth, straight steel, high-density polyethylene, or other plastic rod of equal or greater abrasionresistance with a 16 mm 58 in. 6 2

25、 mm 116 in. diameter. The length of the tamping rod shall be at least 100 mm 4 in. greaterthan the depth of the measuring bowl in which rodding is being performed, but not greater than 600 mm 24 in. in overall length(Note 1). The rod shall have the tamping end or both ends rounded to a hemispherical

26、 tip of the same diameter 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 C231.4.4 Strike-off BarA flat, straight steel bar at least 3 by

27、20 by 300 mm 18 by 34 by 12 in. or a flat, straight high-densitypolyethylene bar, or other plastic of equal or greater abrasion resistance, at least 6 by 20 by 300 mm 14 by 34 by 12 in.4.5 Calibrated CupAmetal or plastic cup either having a capacity of or being graduated in increments equal to 1.006

28、0.04 %of the volume of the measuring bowl of the air meter. The calibrated cup is only to be used to add water when the concrete aircontent exceeds 9 % or the calibrated range of the meter.4.6 Measuring Vessel for Isopropyl AlcoholA vessel with a minimum capacity of at least 500 mL 1 pt with graduat

29、ions notlarger than 100 mL 4 oz for measuring a quantity of isopropyl alcohol.4.7 SyringeA rubber syringe having a capacity of at least 50 mL 2 oz.4.8 Pouring Vessel for WaterA container of approximately 1 L 1 qt capacity.4.9 Scoop of a size large enough so each amount of concrete obtained from the

30、sampling receptacle is representative and smallenough so it is not spilled during placement in the measuring bowl.4.10 Isopropyl AlcoholUse 70 % by volume isopropyl alcohol (approximately 65 % by weight) (Note 2). Other foam-dispersing agents are permitted if tests demonstrate that the use of the ag

31、ent does not change the indicated air content, in theFIG. 1 Apparatus for Measuring Air Content of Fresh Concrete by Volumetric Method (b) Aluminum Meter (continued)C173/C173M 163amounts being used, by more than 0.1 % or if correction factors are developed similar to those in Table 1. When other dis

32、persingagents are used, a copy of the records documenting the testing or calculations shall be available in the laboratory.FIG. 1 Apparatus for Measuring Air Content of Fresh Concrete by Volumetric Method (c) High Density Plastic Meter (continued)TABLE 1 Correction for the Effect of Isopropyl Alcoho

33、l 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 0.75A Subtract from final meter reading.B Corrections are applied only when 1.25 L 2.5 pt or more of isopropyl alcohol isused. The values giv

34、en 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 164NOTE 2Seventy percent isopropyl alcohol is commonly available as rubbing alcohol. More concentrated grades can be diluted with water to therequir

35、ed concentration.4.11 MalletA mallet (with a rubber or rawhide head) with a mass of approximately 600 6 200 g 1.25 6 0.5 lb.5. Calibration5.1 Calibrate the meter and calibrated cup initially and annually or whenever there is reason to suspect damage or deformationof the meter or calibrated cup.5.2 D

36、etermine the volume of the measuring bowl with an accuracy of at least 0.1 % by determining the mass of water requiredto fill it at room temperature and dividing it by the density of the water at the same temperature. Follow the calibration procedureoutlined in Test Method C29/C29M.5.3 Determine the

37、 accuracy of the graduations on the neck of the top section of the air meter by filling the assembled measuringbowl and top section with water to the level of the mark for highest air content graduation.5.3.1 Add water in increments of 1.0 % of the volume of the measuring bowl to check accuracy thro

38、ughout the graduated rangeof air content. The error at any point throughout the graduated range shall not exceed 0.1 % of air.5.4 Determine the volume of the calibrated cup using water at 21.1C 70F by the method outlined in 5.2. A quick check canbe made by adding one or more calibrated cups of water

39、 to the assembled apparatus and observing the increase in the height ofthe water column after filling to a given level.6. Sampling6.1 Obtain the sample of freshly mixed concrete in accordance with Practice C172. If the concrete contains coarse aggregateparticles that would be retained on a 37.5-mm 1

40、12-in. sieve, wet sieve a representative sample over a 25-mm 1-in. sieve to yieldsomewhat more than enough material to fill the measuring bowl. The wet sieving procedure is described in Practice C172.6.2 The concrete used to fill the measuring bowl shall not have been previously used in the performa

41、nce of any other test orpractice, other than wet sieving in accordance with Practice C172 or the temperature test in accordance with Test MethodC1064/C1064M.7. Procedure7.1 Rodding and TappingWetDampen the insideinterior of the measuring bowl and dry it to a damp but not shiny appearance.remove any

42、standing water from the bottom. Using the scoop described in 4.9, fill the measuring bowl with freshly mixed concretein two layers of approximately equal volume. While placing the concrete in the measuring bowl, move the scoop around theperimeter of the measuring bowl opening to ensure an even distr

43、ibution of the concrete with minimal segregation. Rod each layer25 times uniformly over the cross section with the rounded end of the rod. Rod the bottom layer throughout its depth. In roddingthis layer, use care not to damage the bottom of the measuring bowl. For the upper layer, allow the rod to p

44、enetrate through thelayer being rodded and into the layer below approximately 25 mm 1 in.After each layer is rodded, tap the sides of the measuringbowl 10 to 15 times with the mallet to close any voids left by the tamping rod and to release any large bubbles of air that mayhave been trapped.After ta

45、pping the final layer, a slight excess of concrete, 3 mm 18 in. or less, above the rim is acceptable.Addor remove a representative sample of concrete if necessary to obtain the required amount of concrete.7.2 Striking OffAfter rodding and tapping of the second layer, strike off the excess concrete w

46、ith the strike-off bar until thesurface is flush with the top of the measuring bowl. Wipe the flange of the measuring bowl clean.7.3 Adding Water and AlcoholWet the inside of the top section of the meter, including the gasket. Attach the top section tothe measuring bowl and insert the funnel. Add at

47、 least 0.5 L 1 pt of water followed by the selected amount (Note 3) of isopropylalcohol. Record the amount of isopropyl alcohol added. Continue adding water at least until it appears in the graduated neck ofthe top section (Note 4). Remove the funnel. Adjust the liquid level until the bottom of the

48、meniscus is level with the zero markon the graduated neck. A rubber syringe is useful for this purpose. Attach and tighten the watertight cap.NOTE 3The amount of isopropyl alcohol necessary to obtain a stable reading, and a minimum amount of foam immediately above the water column,will depend upon a

49、 number of factors. Many concretes made with less than 300 kg/m3 500 lb/yd3 of cement and air contents less than 4 % may requireless than 0.2 L 0.5 pt of alcohol. Some high-cement mixes made with silica fume that have air contents of 6 % or more may require more than 1.4 L3 pt of alcohol. The amount required will vary with the concrete air content, the amount and type of air-entraining admixture, the cement content andcement alkali content, and perhaps other factors. Generally, the amount of alcoh