1、Designation:C138/C138M10b Designation: C138/C138M 12American Association StateHighway and Transportation Officials StandardAASHTO No.: T121Standard Test Method forDensity (Unit Weight), Yield, and Air Content (Gravimetric)of Concrete1This standard is issued under the fixed designation C138/C138M; th
2、e number immediately following the designation indicates the yearof original adoption or, in the case of revision, 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.Thi
3、s standard has been approved for use by agencies of the Department of Defense.1. Scope*1.1 This test method covers determination of the density (see Note 1) of freshly mixed concrete and gives formulas forcalculating the yield, cement content, and air content of the concrete. Yield is defined as the
4、 volume of concrete produced froma mixture of known quantities of the component materials.1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in eachsystem may not be exact equivalents; therefore, each system shall be used indepen
5、dently of the other. Combining values from thetwo systems may result in non-conformance with the standard.NOTE 1Unit weight was the previous terminology used to describe the property determined by this test method, which is mass per unit volume.1.3 The text of this test method references notes and f
6、ootnotes that provide explanatory information. These notes and footnotes(excluding those in tables) shall not be considered as requirements of this test method.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the us
7、er 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 skinand tissue upon prolonged exposure.2)2. Referenced Documents2.
8、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 FieldC143/C143M Test Method for Slump of Hydraulic-Cement ConcreteC150 Specification for Portland CementC172 Practice for Sampling Freshl
9、y Mixed ConcreteC173/C173M Test Method for Air Content of Freshly Mixed Concrete by the Volumetric MethodC188 Test Method for Density of Hydraulic CementC231 Test Method for Air Content of Freshly Mixed Concrete by the Pressure Method3. Terminology3.1 Symbols:A = air content (percentage of voids) in
10、 the concreteC = actual cement content, lb/yd3or kg/m3Cb= mass of cement in the batch, lb or kgD = density (unit weight) of concrete, lb/ft3or kg/m3M = total mass of all materials batched, lb or kg (see Note 3)Mc= mass of the measure filled with concrete, lb or kg1This test method is under the juris
11、diction of ASTM Committee C09 on Concrete and Concrete Aggregates and is the direct responsibility of Subcommittee C09.60 onTesting Fresh Concrete.Current edition approved Oct.May 1, 2010.2012. Published November 2010.June 2012. Originally approved in 1938. Last previous edition approved in 2010 asC
12、138/C138M10ab. DOI: 10.1520/C0138_C0138M-10b2.2See section 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, or contact ASTM Customer Service at serviceastm.org. For Annual
13、Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.1This 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. Becauseit may not be te
14、chnically 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 appears at the end of th
15、is standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Mm= mass of the measure, lb or kgRy= relative yieldT = theoretical density of the concrete computed on an airfree basis, lb/ft3or kg/m3(see Note 2)Y = yield, volume of concre
16、te produced per batch, yd3or m3Yd= volume of concrete which the batch was designed to produce, yd3or m3Yf= volume of concrete produced per batch, ft3V = total absolute volume of the component ingredients in the batch, ft3or m3Vm= volume of the measure, ft3or m3NOTE 2The theoretical density is, custo
17、marily, a laboratory determination, the value for which is assumed to remain constant for all batches madeusing identical component ingredients and proportions. It is calculated from the following equation:T 5 M/V (1)C0138_C0138M-12_1The absolute volume of each ingredient in cubic feet is equal to t
18、he quotient of the mass of that ingredient divided by the product of its specific gravitytimes 62.4. The absolute volume of each ingredient in cubic metres is equal to the mass of the ingredient in kilograms divided by 1000 times its specificgravity. For the aggregate components, the bulk specific g
19、ravity and mass should be based on the saturated, surface-dry condition. For cement, the actualspecific gravity should be determined by Test Method C188. A value of 3.15 may be used for cements manufactured to meet the requirements ofSpecification C150.NOTE 3The total mass of all materials batched i
20、s the sum of the masses of the cement, the fine aggregate in the condition used, the coarse aggregatein the condition used, the mixing water added to the batch, and any other solid or liquid materials used.4. Apparatus4.1 BalanceA balance or scale accurate to 0.1 lb 45 g or to within 0.3 % of the te
21、st load, whichever is greater, at any pointwithin the range of use. The range of use shall be considered to extend from the mass of the measure empty to the mass of themeasure plus its contents at 160 lb/ft32600 kg/m3.4.2 Tamping RodA round, smooth, straight steel rod, with a58 in. 16 mm 6116 in. 2
22、mm diameter. The length of thetamping rod shall be at least 4 in. 100 mm greater than the depth of the measure in which rodding is being performed, but notgreater than 24 in. 600 mm in overall length (See Note 4). The rod shall have the tamping end or both ends rounded to ahemispherical tip of the s
23、ame diameter as the rod.NOTE 4Arod length of 16 in. 400 mm to 24 in. 600 mm meets the requirements of the following: Practice C31/C31M, Test Method C138/C138M,Test Method C143/C143M, Test Method C173/C173M and Test Method C231.4.3 Internal VibratorInternal vibrators may have rigid or flexible shafts
24、, preferably powered by electric motors. Thefrequency of vibration shall be 7000 vibrations per minute or greater while in use. The outside diameter or the side dimension ofthe vibrating element shall be at least 0.75 in. 19 mm and not greater than 1.50 in. 38 mm. The length of the shaft shall be at
25、least 24 in. 600 mm.4.4 MeasureA cylindrical container made of steel or other suitable metal (see Note 5). The minimum capacity of the measureshall conform to the requirements of Table 1 based on the nominal size of aggregate in the concrete to be tested. All measures,except for measuring bowls of a
26、ir meters which are also used for Test Method C138/C138M tests, shall conform to therequirements of Test Method C29/C29M. When measuring bowls of air meters are used, they shall conform to the requirementsof Test Method C231, and shall be calibrated for volume as described in Test Method C29/C29M. T
27、he top rim of the air meterbowls shall be smooth and plane within 0.01 in. 0.3 mm (see Note 6).NOTE 5The metal should not be readily subject to attack by cement paste. However, reactive materials such as aluminum alloys may be used ininstances where as a consequence of an initial reaction, a surface
28、 film is rapidly formed which protects the metal against further corrosion.NOTE 6The top rim is satisfactorily plane if a 0.01-in. 0.3-mm feeler gage cannot be inserted between the rim and a piece of14-in. 6-mm or thickerplate glass laid over the top of the measure.4.5 Strike-Off PlateA flat rectang
29、ular metal plate at least14 in. 6 mm thick or a glass or acrylic plate at least12 in. 12 mmthick with a length and width at least 2 in. 50 mm greater than the diameter of the measure with which it is to be used. The edgesof the plate shall be straight and smooth within a tolerance of116 in. 2 mm.TAB
30、LE 1 Capacity of MeasuresNominal Maximum Sizeof Coarse AggregateCapacity of MeasureAin. mm ft3L1 25.0 0.2 6112 37.5 0.4 11250 .5 4375 1 28412 112 2.5 706 150 3.5 100AThe indicated size of measure shall be used to test concrete containingaggregates of a nominal maximum size equal to or smaller than t
31、hat listed. Theactual volume of the measure shall be at least 95 % of the nominal volume listed.C138/C138M 1224.6 MalletA mallet (with a rubber or rawhide head) having a mass of 1.25 6 0.50 lb 600 6 200 g for use with measuresof 0.5 ft314 L or smaller, and a mallet having a mass of 2.25 6 0.50 lb 10
32、00 6 200 g for use with measures larger than 0.5ft3.4.7 Scoopof a size large enough so each amount of concrete obtained from the sampling receptacle is representative and smallenough so it is not spilled during placement in the measure.5. Sample5.1 Obtain the sample of freshly mixed concrete in acco
33、rdance with Practice C172.6. Procedure6.1 Base the selection of the method of consolidation on the slump, unless the method is stated in the specifications under whichthe work is being performed. The methods of consolidation are rodding and internal vibration. Rod concretes with a slump greaterthan
34、3 in. 75 mm. Rod or vibrate concrete with a slump of 1 to 3 in. 25 to 75 mm. Consolidate concretes with a slump lessthan 1 in. by vibration.NOTE 7Nonplastic concrete, such as is commonly used in the manufacture of pipe and unit masonry, is not covered by this test method.6.2Place the concrete in the
35、 measure using the scoop described in6.2 Dampen the interior of the measure and place it on a flat, level, firm surface. Place the concrete in the measure using thescoop described in 4.7. Move the scoop around the perimeter of the measure opening to ensure an even distribution of the concretewith mi
36、nimal segregation. Fill the measure in the number of layers required by the consolidation method (6.3 or 6.4).6.3 RoddingPlace the concrete in the measure in three layers of approximately equal volume. Rod each layer with 25 strokesof the tamping rod when nominal 0.5-ft314-L or smaller measures are
37、used, 50 strokes when nominal 1-ft328-L measuresare used, and one stroke per 3 in.220 cm3 of surface for larger measures. Rod each layer uniformly over the cross section withthe rounded end of the rod using the required number of strokes. Rod the bottom layer throughout its depth. In rodding this la
38、yer,use care not to damage the bottom of the measure. For each upper layer, allow the rod to penetrate through the layer being roddedand into the layer below approximately 1 in. 25 mm. After each layer is rodded, tap the sides of the measure 10 to 15 times withthe appropriate mallet (see 4.6) using
39、such force so as to close any voids left by the tamping rod and to release any large bubblesof air that may have been trapped. Add the final layer so as to avoid overfilling.6.4 Internal VibrationFill and vibrate the measure in two approximately equal layers. Place all of the concrete for each layer
40、in the measure before starting vibration of that layer. Insert the vibrator at three different points for each layer. In compacting thebottom layer, do not allow the vibrator to rest on or touch the bottom or sides of the measure. In compacting the final layer, thevibrator shall penetrate into the u
41、nderlying layer approximately 1 in. 25 mm. Take care that the vibrator is withdrawn in sucha manner that no air pockets are left in the specimen. The duration of vibration required will depend upon the workability of theconcrete and the effectiveness of the vibrator (see Note 8). Continue vibration
42、only long enough to achieve proper consolidationof the concrete (see Note 9). Observe a constant duration of vibration for the particular kind of concrete, vibrator, and measureinvolved.NOTE 8Usually, sufficient vibration has been applied as soon as the surface of the concrete becomes relatively smo
43、oth.NOTE 9Overvibration may cause segregation and loss of appreciable quantities of intentionally entrained air.6.5 On completion of consolidation the measure must not contain a substantial excess or deficiency of concrete. An excess ofconcrete protruding approximately18 in. 3 mm above the top of th
44、e mold is optimum.Asmall quantity of concrete may be addedto correct a deficiency. If the measure contains a great excess of concrete at completion of consolidation, remove a representativeportion of the excess concrete with a trowel or scoop immediately following completion of consolidation and bef
45、ore the measureis struck-off.6.6 Strike-OffAfter consolidation, strike-off the top surface of the concrete and finish it smoothly using the flat strike-off plateso that the measure is level full. Strike-off the measure by pressing the strike-off plate on the top surface of the measure to coverabout
46、two thirds of the surface and withdraw the plate with a sawing motion to finish only the area originally covered. Then placethe plate on the top of the measure to cover the original two thirds of the surface and advance it with a vertical pressure and asawing motion to cover the whole surface of the
47、 measure and continue to advance it until it slides completely off the measure.Incline the plate and perform final strokes with the edge of the plate to produce a smooth surface.6.7 Cleaning and WeighingAfter strike-off, clean all excess concrete from the exterior of the measure and determine the ma
48、ssof the concrete and measure to an accuracy consistent with the requirements of 4.1.7. Calculation7.1 Density (Unit Weight)Calculate the net mass of the concrete in pounds or kilograms by subtracting the mass of themeasure, Mm, from the mass of the measure filled with concrete, Mc. Calculate the de
49、nsity, D,ft3or yd3,by dividing the net massof concrete by the volume of the measure, Vmas follows:C0138_C0138M-12_27.2 YieldCalculate the yield as follows:C138/C138M 123C0138_C0138M-12_3orC0138_C0138M-12_47.3 Relative YieldRelative yield is the ratio of the actual volume of concrete obtained to the volume as designed for the batch(see Note 10) calculated as follows:C0138_C0138M-12_5NOTE 10A value for Rygreater than 1.00 indicates an excess of concrete being produced whereas a value less tha
