1、Designation: C138/C138M 12 C138/C138M 12a American 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; the number i
2、mmediately 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.This standard
3、 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 volume of
4、 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 independently of
5、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 footnotes t
6、hat 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 user of this
7、 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 Documents2.1 ASTM Sta
8、ndards: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 Freshly Mixed
9、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 the con
10、creteC = actual cement content, lb/yd3 or kg/m3Cb = mass of cement in the batch, lb or kg1 This test method is under the jurisdiction of ASTM Committee C09 on Concrete and Concrete Aggregatesand is the direct responsibility of Subcommittee C09.60 onTesting Fresh Concrete.Current edition approved May
11、 1, 2012Dec. 1, 2012. Published June 2012December 2012. Originally approved in 1938. Last previous edition approved in 20102012 asC138/C138M10b.12. DOI: 10.1520/C0138_C0138M-12.10.1520/C0138_C0138M-12a.2 See section on Safety Precautions, Manual of Aggregate and Concrete Testing, Annual Book of ASTM
12、 Standards, Vol. 04.02.3 For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at serviceastm.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 standa
13、rd 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 technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases
14、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 this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1D = density (unit
15、weight) of concrete, lb/ft3 or kg/m3M = total mass of all materials batched, lb or kg (see Note 3)Mc = mass of the measure filled with concrete, lb or kgMm = mass of the measure, lb or kgRy = relative yieldT = theoretical density of the concrete computed on an airfree basis, lb/ft3 or kg/m3 (see Not
16、e 2)Y = yield, volume of concrete produced per batch, yd3 or m3Yd = volume of concrete which the batch was designed to produce, yd3 or m3Yf = volume of concrete produced per batch, ft3V = total absolute volume of the component ingredients in the batch, ft3 or m3Vm = volume of the measure, ft3 or m3A
17、 = air content (percentage of voids) in the concreteC = actual cement content, kg/m3 lb/yd3Cb = mass of cement in the batch, kg lbD = density (unit weight) of concrete, kg/m3 lb/ft3M = total mass of all materials batched, kg lb (see Note 3)Mc = mass of the measure filled with concrete, kg lb orMm =
18、mass of the measure, kg lbRy = relative yieldT = theoretical density of the concrete computed on an airfree basis, kg/m3 lb/ft3 (see Note 2)Y = yield, volume of concrete produced per batch, m3 yd3Yd = volume of concrete which the batch was designed to produce, m3 yd3Yf = volume of concrete produced
19、per batch, m3 ft3V = total absolute volume of the component ingredients in the batch, m3 ft3Vm = volume of the measure, m3 ft3NOTE 2The theoretical density is, customarily, a laboratory determination, the value for which is assumed to remain constant for all batches madeusing identical component ing
20、redients and proportions. It is calculated from the following equation:T 5M/V (1)The absolute volume of each ingredient in cubic feet is equal to the quotient of the mass of that ingredient divided by the product of its specificgravity times 62.4. The absolute volume of each ingredient in cubic metr
21、es is equal to the mass of the ingredient in kilograms divided by 1000 timesits specific gravity. For the aggregate components, the bulk specific gravity and mass should be based on the saturated, surface-dry condition. Forcement, the actual specific gravity should be determined by Test Method C188.
22、 A value of 3.15 may be used for cements manufactured to meet therequirements of Specification C150.NOTE 3The total mass of all materials batched is 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
23、 batch, and any other solid or liquid materials used.4. Apparatus4.1 BalanceA balance or scale accurate to 0.1 lb 45 g45 g 0.1 lb or to within 0.3 % of the test load, whichever is greater,at any point within the range of use. The range of use shall be considered to extend from the mass of the measur
24、e empty to themass of the measure plus its contents at 160 lb/ft2600 kg/m3 2600 kg/m 160 lb/ft3.4.2 Tamping RodA round, smooth, straight steel rod, with a 16 mm 58 in. 16 mm 6 in. 6 2 mm 116 in. 2 mm in.diameter. The length of the tamping rod shall be at least 4 in. 100 mm100 mm 4 in. greater than t
25、he depth of the measure inwhich rodding is being performed, but not greater than 24 in. 600 mm600 mm 24 in. in overall length (See Note 4). The rodshall have the tamping end or both ends rounded to a hemispherical tip of the same diameter as the rod.NOTE 4A rod length of 16 in. 400 mm to 24 in. 600
26、mm400 mm 16 in. to 600 mm 24 in. meets the requirements of the following: PracticeC31/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, preferably powered by electric motors. Th
27、e frequencyof vibration shall be 7000 vibrations per minute or greater while in use. The outside diameter or the side dimension of the vibratingelement shall be at least 0.75 in. 19 mm19 mm 0.75 in. and not greater than 1.50 in. 38 mm.38 mm 1.50 in. The lengthof the shaft shall be at least 24 in. 60
28、0 mm.600 mm 24 in.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 air
29、 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. The
30、 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 f
31、ilm is rapidly formed which protects the metal against further corrosion.C138/C138M 12a2NOTE 6The top rim is satisfactorily plane if a 0.01-in. 0.3-mm0.3-mm 0.01-in. feeler gage cannot be inserted between the rim and a piece of 14-in.6-mm6-mm 14-in. or thicker plate glass laid over the top of the me
32、asure.4.5 Strike-Off PlateA flat rectangular metal plate at least 6 mm 14 in. 6 mmin. thick or a glass or acrylic plate at least 12mm 12 in. 12 mmin. thick with a length and width at least 2 in. 50 mm50 mm 2 in. greater than the diameter of the measurewith which it is to be used. The edges of the pl
33、ate shall be straight and smooth within a tolerance of 2 mm 116 in. 2 mm.in.4.6 MalletA mallet (with a rubber or rawhide head) having a mass of 1.25 6 0.50 lb 600 6 200 g600 6 200 g 1.25 6 0.50lb for use with measures of 0.5 14 L 0.5 ft3 14 L or smaller, and a mallet having a mass of 2.25 6 0.50 lb
34、1000 6 200g1000 6 200 g 2.25 6 0.50 lb for use with measures larger than 0.5 14 L 0.5 ft3.4.7 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 sa
35、mple of freshly mixed concrete in accordance 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. R
36、od concretes with a slump greaterthan 3 in. 75 mm.75 mm 3 in. Rod or vibrate concrete with a slump of 1 to 3 in. 25 to 75 mm.25 to 75 mm 1 to 3 in.Consolidate concretes with a slump less than 1 in. 25 mm 1 in. by vibration.NOTE 7Nonplastic concrete, such as is commonly used in the manufacture of pip
37、e and unit masonry, is not covered by this test method.6.2 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 t
38、he concretewith minimal 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-ft14-L 3 14-L
39、0.5-ft3 or smaller measures are used, 50 strokes when nominal 1-ft28-L 328-L 1-ft3 measures are used, and one stroke per 3 in.20 cm2 20 cm3 in.32 of surface for larger measures. Rod each layeruniformly over the cross section with the rounded end of the rod using the required number of strokes. Rod t
40、he bottom layerthroughout its depth. In rodding this layer, use care not to damage the bottom of the measure. For each upper layer, allow the rodto penetrate through the layer being rodded and into the layer below approximately 1 in. 25 mm.25 mm 1 in. After each layeris rodded, tap the sides of the
41、measure 10 to 15 times with the appropriate mallet (see 4.6) using such force so as to close any voidsleft by the tamping rod and to release any large bubbles of air that may have been trapped. Add the final layer so as to avoidoverfilling.6.4 Internal VibrationFill and vibrate the measure in two ap
42、proximately equal layers. Place all of the concrete for each layerin the measure before starting vibration of that layer. Insert the vibrator at three different points for each layer. In compacting theTABLE 1 Capacity of MeasuresNominal Maximum Sizeof Coarse Aggregate Capacity of MeasureAin. mm ft3
43、L1 25.0 0.2 6112 37.5 0.4 112 50 0.5 143 75 1.0 28412 112 2.5 706 150 3.5 100TABLE 1 Capacity of MeasuresNominal Maximum Sizeof Coarse Aggregate Capacity of MeasureAmm in. L ft325.0 1 6 0.237.5 112 11 0.450 2 14 0.575 3 28 1.0112 412 70 2.5150 6 100 3.5A The indicated size of measure shall be used t
44、o test concrete containingaggregates of a nominal maximum size equal to or smaller than that listed. Theactual volume of the measure shall be at least 95 % of the nominal volume listed.C138/C138M 12a3bottom layer, do not allow the vibrator to rest on or touch the bottom or sides of the measure. In c
45、ompacting the final layer, thevibrator shall penetrate into the underlying layer approximately 1 in. 25 mm. 25 mm 1 in. . Take care that the vibrator iswithdrawn in such a manner that no air pockets are left in the specimen. The duration of vibration required will depend upon theworkability of the c
46、oncrete and the effectiveness of the vibrator (see Note 8). Continue vibration only long enough to achieveproper consolidation of the concrete (see Note 9). Observe a constant duration of vibration for the particular kind of concrete,vibrator, and measure involved.NOTE 8Usually, sufficient vibration
47、 has been applied as soon as the surface of the concrete becomes relatively smooth.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 concret
48、e. An excess ofconcrete protruding approximately 3 mm 18 in. 3 mmin. above the top of the mold is optimum. A small quantity of concretemay be added to correct a deficiency. If the measure contains a great excess of concrete at completion of consolidation, removea representative portion of the excess
49、 concrete with a trowel or scoop immediately following completion of consolidation andbefore the measure is 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
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