ASTM C231-2008b Standard Test Method for Air Content of Freshly Mixed Concrete by the Pressure Method.pdf
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1、Designation: C 231 08bStandard Test Method forAir Content of Freshly Mixed Concrete by the PressureMethod1This standard is issued under the fixed designation C 231; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last r
2、evision. A number in parentheses indicates the year of last reapproval. Asuperscript 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 determination of t
3、he air contentof freshly mixed concrete from observation of the change involume of concrete with a change in pressure.1.2 This test method is intended for use with concretes andmortars made with relatively dense aggregates for which theaggregate correction factor can be satisfactorily determined byt
4、he technique described in Section 6. It is not applicable toconcretes made with lightweight aggregates, air-cooled blast-furnace slag, or aggregates of high porosity. In these cases, TestMethod C 173/C 173M should be used. This test method isalso not applicable to nonplastic concrete such as is comm
5、onlyused in the manufacture of pipe and concrete masonry units.1.3 The text of this test method references notes andfootnotes that provide explanatory information. These notesand footnotes (excluding those in tables and figures) shall notbe considered as requirements of this standard.1.4 The values
6、stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its
7、 use. It is 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 prolo
8、nged exposure.)22. Referenced Documents2.1 ASTM Standards:3C 138/C 138M Test Method for Density (Unit Weight),Yield, and Air Content (Gravimetric) of ConcreteC 172 Practice for Sampling Freshly Mixed ConcreteC 173/C 173M Test Method for Air Content of FreshlyMixed Concrete by the Volumetric MethodC
9、192/C 192M Practice for Making and Curing ConcreteTest Specimens in the LaboratoryC 670 Practice for Preparing Precision and Bias Statementsfor Test Methods for Construction MaterialsE 177 Practice for Use of the Terms Precision and Bias inASTM Test Methods3. Significance and Use3.1 This test method
10、 covers the determination of the aircontent of freshly mixed concrete. The test determines the aircontent of freshly mixed concrete exclusive of any air that mayexist inside voids within aggregate particles. For this reason, itis applicable to concrete made with relatively dense aggregateparticles a
11、nd requires determination of the aggregate correctionfactor (see 6.1 and 9.1).3.2 This test method and Test Method C 138/C 138M andC 173/C 173M provide pressure, gravimetric, and volumetricprocedures, respectively, for determining the air content offreshly mixed concrete. The pressure procedure of t
12、his testmethod gives substantially the same air contents as the othertwo test methods for concretes made with dense aggregates.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 amount of consolidation effo
13、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
14、ocesses at which the air content of the unhardened concreteis determined, that is, before or after the concrete goes througha pump; and other factors.1This test method is under the jurisdiction of ASTM Committee C09 onConcrete and Concrete Aggregates and is the direct responsibility of SubcommitteeC
15、09.60 on Testing Fresh Concrete.Current edition approved June 1, 2008. Published July 2008. Originally approvedin 1949. Last previous edition approved in 2008 as C 231 08a.2Section on Safety Precautions, Manual of Aggregate and Concrete Testing,Annual Book of ASTM Standards, Vol 04.02.3For reference
16、d 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 website.1*A Summary of Changes section appears at the end of this standard.Copyrigh
17、t ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4. Apparatus4.1 Air MetersThere are available satisfactory apparatusof two basic operational designs employing the principle ofBoyles law. For purposes of reference herein these aredesignated Me
18、ter Type A and Meter Type B.4.1.1 Meter Type AAn air meter consisting of a measuringbowl and cover assembly (see Fig. 1) conforming to therequirements of 4.2 and 4.3. The operational principle of thismeter consists of introducing water to a predetermined heightabove a sample of concrete of known vol
19、ume, and theapplication of a predetermined air pressure over the water. Thedetermination consists of the reduction in volume of the air inthe concrete sample by observing the amount the water level islowered under the applied pressure, the latter amount beingcalibrated in terms of percent of air in
20、the concrete sample.4.1.2 Meter Type BAn air meter consisting of a measuringbowl and cover assembly (see Fig. 2) conforming to therequirements of 4.2 and 4.3. The operational principle of thismeter consists of equalizing a known volume of air at a knownpressure in a sealed air chamber with the unkno
21、wn volume ofair in the concrete sample, the dial on the pressure gauge beingcalibrated in terms of percent air for the observed pressure atwhich equalization takes place. Working pressures of 7.5 to30.0 psi (51 to 207 kPa) have been used satisfactorily.4.2 Measuring BowlThe measuring bowl shall be e
22、ssen-tially cylindrical in shape, made of steel, hard metal, or otherhard material not readily attacked by the cement paste, havinga minimum diameter equal to 0.75 to 1.25 times the height, anda capacity of at least 0.20 ft3(5.7 L). It shall be flanged orotherwise constructed to provide for a pressu
23、re tight fitbetween measuring bowl and cover assembly. The interiorsurfaces of the measuring bowl and surfaces of rims, flanges,and other component fitted parts shall be machined smooth.The measuring bowl and cover assembly shall be sufficientlyrigid to limit the expansion factor, D, of the apparatu
24、s assembly(Annex A1.5) to not more than 0.1 % of air content on theindicator scale when under normal operating pressure.4.3 Cover Assembly:4.3.1 The cover assembly shall be made of steel, hard metal,or other hard material not readily attacked by the cement paste.It shall be flanged or otherwise cons
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