AASHTO T 23-2014 Standard Method of Test for Making and Curing Concrete Test Specimens in the Field.pdf

1、Standard Method of Test for Making and Curing Concrete Test Specimens in the Field AASHTO Designation: T 23-141ASTM Designation: C 31-06 American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-3c T 23-1 AASHTO Standard Met

2、hod of Test for Making and Curing Concrete Test Specimens in the Field AASHTO Designation: T 23-141ASTM Designation: C 31-06 1. SCOPE 1.1. This method covers procedures for making and curing cylinder and beam specimens from representative samples of fresh concrete for a construction project. 1.2. Th

3、e concrete used to make the molded specimens shall be sampled after all on-site adjustments have been made to the mixture proportions, including the addition of mix water and admixtures. This practice is not satisfactory for making specimens from concrete not having measurable slump or requiring oth

4、er sizes or shapes of specimens. 1.3. The values stated in SI units are to be regarded as the standard. 1.4. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety an

5、d health practices and determine the applicability of regulatory limitations prior to use. WarningFresh hydraulic cementitious mixtures are caustic and may cause chemical burns to exposed skin and tissue upon prolonged exposure. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: M 195, Lightweight Aggre

6、gates for Structural Concrete M 201, Mixing Rooms, Moist Cabinets, Moist Rooms, and Water Storage Tanks Used in the Testing of Hydraulic Cements and Concretes M 205M/M 205, Molds for Forming Concrete Test Cylinders Vertically R 39, Making and Curing Concrete Test Specimens in the Laboratory R 60, Sa

7、mpling Freshly Mixed Concrete T 119M/T 119, Slump of Hydraulic Cement Concrete T 121M/T 121, Density (Unit Weight), Yield, and Air Content (Gravimetric) of Concrete T 152, Air Content of Freshly Mixed Concrete by the Pressure Method T 196M/T 196, Air Content of Freshly Mixed Concrete by the Volumetr

8、ic Method T 197M/T 197, Time of Setting of Concrete Mixtures by Penetration Resistance T 231, Capping Cylindrical Concrete Specimens T 309M/T 309, Temperature of Freshly Mixed Hydraulic Cement Concrete 2014 by the American Association of State Highway and Transportation Officials.All rights reserved

9、. Duplication is a violation of applicable law.TS-3c T 23-2 AASHTO 2.2. ASTM Standard: C 125, Standard Terminology Relating to Concrete and Concrete Aggregates 2.3. ACI Standard: ACI 309R, Guide for Consolidation of Concrete 3. TERMINOLOGY 3.1. For definitions of terms used in this practice, refer t

10、o ASTM C 125. 4. SIGNIFICANCE AND USE 4.1. This method provides standardized requirements for making, curing, protecting, and transporting concrete test specimens under field conditions. 4.2. If the specimens are made and standard cured, as stipulated herein, the resulting strength test data where t

11、he specimens are tested are able to be used for the following purposes: 4.2.1. Acceptance testing for specified strength, 4.2.2. Checking the adequacy of mixture proportions for strength, 4.2.3. Quality control. 4.3. If the specimens are made and field cured, as stipulated herein, the resulting stre

12、ngth test data when the specimens are tested are able to be used for the following purposes: 4.3.1. Determination of whether a structure is capable of being put in service, 4.3.2. Comparison with test results of standard cured specimens or with test results from various in-place test methods, 4.3.3.

13、 Adequacy of curing and protection of concrete in the structure, or 4.3.4. Form or shoring removal time requirements. 5. APPARATUS 5.1. Molds, GeneralMolds for specimens or fastenings thereto in contact with the concrete shall be made of steel, cast iron, or other nonabsorbent material, nonreactive

14、with concrete containing portland or other hydraulic cements. Molds shall hold their dimensions and shape under conditions of use. Molds shall be watertight during use as judged by their ability to hold water poured into them. Provisions for tests of watertightness are given in M 205M/M 205. A suita

15、ble sealant, such as heavy grease, modeling clay, or microcrystalline wax shall be used where necessary to prevent leakage through the joints. Positive means shall be provided to hold base plates firmly to the molds. Reusable molds shall be lightly coated with mineral oil or a suitable nonreactive f

16、orm release material before use. 2014 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c T 23-3 AASHTO 5.2. CylinderMolds for casting concrete test specimens shall conform to the requirements of M 205M/M 2

17、05. 5.3. Beam MoldsBeam molds shall be of the shape and dimensions required to produce the specimens stipulated in Section 6.2. The inside surfaces of the molds shall be smooth. The sides, bottom, and ends shall be at right angles to each other and shall be straight and true and free of warpage. Max

18、imum variation from the nominal cross section shall not exceed 3.2 mm (1/8in.) for molds with depth or breadth of 152 mm (6 in.) or more. Molds shall produce specimens not more than 1.6 mm (1/16in.) shorter than the required length in accordance with Section 5.2, but may exceed it by more than that

19、amount. 5.4. Tamping RodsThree sizes are specified as indicated in Table 1. Each shall be a round, straight steel rod with at least the tamping end rounded to a hemispherical tip of the same diameter as the rod. Both ends may be rounded if preferred. Table 1Tamping Rod Requirements Rod DimensionsaDi

20、ameter of Cylinder or Width of Beam, mm (in.) Diameter, mm (in.) Length of Rod, mm (in.) 150 (6) 10 (3/8) 300 (12) 150 (6) 16 (5/8) 500 (20) 225 (9) 16 (5/8) 650 (26) aRod tolerances length 100 mm (4 in.) and diameter 2 mm (1/16 in.). 5.5. VibratorsInternal vibrators shall be used. The vibrator freq

21、uency shall be at least 7000 vibrations per minute (117 Hz) while the vibrator is operating in the concrete. The diameter of a round vibrator shall be no more than one-fourth the diameter of the cylinder mold or one-fourth the width of the beam mold. Other shaped vibrators shall have a perimeter equ

22、ivalent to the circumference of an appropriate round vibrator. The combined length of the vibrator shaft and vibrating element shall exceed the depth of the section being vibrated by at least 75 mm (3 in.). The vibrator frequency shall be checked periodically. Note 1For information on size and frequ

23、ency of various vibrators and a method to periodically check vibrator frequency, see ACI 309R. 5.6. MalletA mallet with a rubber or rawhide head weighing 0.57 0.23 kg (1.25 0.50 lb) shall be used. 5.7. Small ToolsTools and items that may be required are shovels, pails, trowels, wood float, metal flo

24、at, blunted trowels, straightedge, feeler gauge, scoops, and rules. 5.8. Slump ApparatusThe apparatus for measurement of slump shall conform to the requirements of T 119M/T 119. 5.9. Sampling and Mixing ReceptacleThe receptacle shall be a suitable heavy gauge metal pan, wheelbarrow, or flat, clean,

25、nonabsorbent mixing board of sufficient capacity to allow easy remixing of the entire sample with a shovel or trowel. 5.10. Air Content ApparatusThe apparatus for measuring air content shall conform to the requirements of T 196M/T 196 or T 152. 5.11. Temperature Measuring DevicesThe temperature meas

26、uring devices shall conform to the applicable requirements of T 309M/T 309. 2014 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c T 23-4 AASHTO 6. TEST SPECIMENS 6.1. Compressive Strength SpecimensCompre

27、ssive strength specimens shall be cylinders cast and allowed to set in an upright position. The length shall be twice the diameter. The cylinder diameter shall be at least three times the nominal maximum size of the coarse aggregate. When the nominal maximum size of the coarse aggregate exceeds 50 m

28、m (2 in.), the concrete sample shall be treated by wet sieving through a 50-mm (2-in.) sieve as described in R 60. When the nominal maximum size of the coarse aggregate does not exceed 25.0 mm (1 in.), the specimens may be 100 by 200 mm (4 by 8 in.) cylinders. Note 2When molds in SI units are requir

29、ed and not available, equivalent inch-pound unit size molds should be permitted. 6.2. Flexural Strength SpecimensFlexural strength specimens shall be beams of concrete cast and hardened with long axes horizontal. The length shall be at least 50 mm (2 in.) greater than three times the depth as tested

30、. The ratio of width to depth as molded shall not exceed 1.5. The standard beam shall be 152 by 152 mm (6 by 6 in.) in cross section for concrete with a maximum-size coarse aggregate up to 50 mm (2 in.) or a beam 100 by 100 mm (4 by 4 in.) in cross section with a maximum-size coarse aggregate up to

31、38 mm (1.5 in.). When the nominal maximum size of the coarse aggregate exceeds 50 mm (2 in.), the smaller cross-sectional dimension of the beam shall be at least three times the nominal maximum size of the coarse aggregate. 7. SAMPLING CONCRETE 7.1. The samples used to fabricate test specimens under

32、 this standard shall be obtained in accordance with R 60 unless an alternative procedure has been approved. 7.2. Record the identification of the sample with respect to the location of the concrete represented and the time of casting. 8. SLUMP, AIR CONTENT, AND TEMPERATURE 8.1. SlumpMeasure and reco

33、rd the slump of each batch of concrete, from which specimens are made, immediately after remixing in the receptacle as required in T 119. 8.2. Air ContentDetermine and record the air content in accordance with either T 152 or T 196M/T 196. The concrete used in performing the air content test shall n

34、ot be used in fabricating test specimens. 8.3. TemperatureDetermine and record the temperature in accordance with T 309M/T 309. Note 3Some specifications may require the measurement of the unit weight of concrete. The volume of concrete produced per batch may be desired on some projects. Also, addit

35、ional information on the air content measurements may be desired. Test Method T 121M/T 121 is used to measure the unit weight, yield, and gravimetric air content of freshly mixed concrete. 9. MOLDING SPECIMENS 9.1. Place of MoldingMold specimens promptly on a level, rigid, horizontal surface, free f

36、rom vibration and other disturbances, at a place as near as practicable to the location where they are to be stored. 9.2. Casting the ConcretePlace the concrete in the molds using a scoop, blunted trowel, or shovel. Select each scoopful, trowelful, or shovelful of concrete from the mixing pan to ens

37、ure that it is 2014 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c T 23-5 AASHTO representative of the batch. Remix the concrete in the mixing pan with a shovel or trowel to prevent segregation during

38、the molding of specimens. Move the scoop, trowel, or shovel around the perimeter of the mold opening when adding concrete so the concrete is uniformly distributed within each layer with a minimum of segregation. In placing the final layer, the operator shall attempt to add an amount of concrete that

39、 will exactly fill the mold after compaction. Underfilled molds shall be adjusted with representative concrete during consolidation of the top layer. Overfilled molds shall have excess concrete removed. 9.2.1. Number of LayersMake specimens in layers as indicated in Tables 2 or 3. Table 2Molding Req

40、uirements by Rodding Specimen Type and Size Number of Layers of Approximately Equal Depth Number of Roddings per Layer Cylinders: Diameter, mm (in.) 100 (4) 2 25 150 (6) 3 25 225 (9) 4 50 Beams: Width, mm (in.) 100 (4) to 200 (8) 2 See Section 9.3.2 Over 200 (8) 3 or more equal depths, each not to e

41、xceed 150 mm (6 in.) See Section 9.3.2 Table 3Molding Requirements by Vibration Specimen Type and Size Number of Layers Number of Vibrator Insertions per Layer Approximate Depth of Layer, mm (in.) Cylinders: Diameter, mm (in.) 100 (4) 2 1 One-half depth of specimen 150 (6) 2 2 One-half depth of spec

42、imen 225 (9) 2 4 One-half depth of specimen Beams: Width, mm (in.) 100 (4) to 200 (8) 1 See Section 9.3.3.2 Depth of specimen 200 (8) as near as practicable Over 200 (8) 2 or more See Section 9.3.3.2 Depth of specimen 200 (8) as near as practicable 9.2.2. Select the proper tamping rod from Section 5

43、.4 and Table 1 or the proper vibrator from Section 5.5. If the method of consolidation is rodding, determine molding requirements from Table 2. If the method of consolidation is vibration, determine molding requirements from Table 3. 9.3. Consolidation: 9.3.1. Methods of ConsolidationPreparation of

44、satisfactory specimens requires different methods of consolidation. The methods of consolidation are rodding and vibration. Base the selection of the method of consolidation on the slump, unless the method is stated in the specifications under which the work is being performed. Rod or vibrate concre

45、tes with slump greater than 25 mm (1 in.). Vibrate concretes with slump of less than or equal to 25 mm (1 in.). Concretes of such low water content that they cannot be properly consolidated by the methods described herein, or 2014 by the American Association of State Highway and Transportation Offic

46、ials.All rights reserved. Duplication is a violation of applicable law.TS-3c T 23-6 AASHTO requiring other sizes and shapes of specimens to represent the product or structure, are not covered by this method. Specimens for such concretes shall be made in accordance with the requirements of R 39 with

47、regard to specimen size and shape and method of consolidation. 9.3.2. RoddingPlace the concrete in the mold, in the required number of layers of approximately equal volume. Rod each layer with the rounded end of the rod using the number of roddings specified in Table 2. The number of roddings per la

48、yer required for beams is one for each 13 cm2(2 in.2) top surface area of the specimen. Rod the bottom layer throughout its depth. Distribute the strokes uniformly over the cross section of the mold. For each layer, allow the rod to penetrate through the layer being rodded and into the layer below a

49、pproximately 25 mm (1 in.). After each layer is rodded, tap the outsides of the mold lightly 10 to 15 times with the mallet, to close any holes left by rodding and to release any large air bubbles that may have been trapped. Use an open hand to tap light-gauge single-use molds that are susceptible to damage if tapped with a mallet. After tapping, spade each layer of the concrete along the sides and ends of beam molds with a trowel or other suitable tool. 9.3.3. VibrationMaintain a uniform time period for duration