AASHTO T 23-2018 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 23-181Technical Section: 3b, Fresh Concrete Release: Group 1 (April) ASTM Designation: C31-15a American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Su

2、ite 249 Washington, D.C. 20001 TS-3b T 23-1 AASHTO Standard Method of Test for Making and Curing Concrete Test Specimens in the Field AASHTO Designation: T 23-181Technical Section: 3b, Fresh Concrete Release: Group 1 (April) ASTM Designation: C31-15a 1. SCOPE 1.1. This method covers procedures for m

3、aking and curing cylinder and beam specimens from representative samples of fresh concrete for a construction project. 1.2. The 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

4、 admixtures. This practice is not satisfactory for making specimens from concrete not having measurable slump or requiring other sizes or shapes of specimens. 1.3. The values stated in SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be

5、 exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with 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 responsibil

6、ity of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Warning Fresh hydraulic cementitious mix tures are caustic and may cause chemical burns to exposed skin and tissue upon prolonged exposure. 1.

7、5. The text of this standard references notes that provide explanatory material. These notes shall not be considered as requirements of the standard. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: M 195, Lightweight Aggregates for Structural Concrete M 201, Mixing Rooms, Moist Cabinets, Moist Rooms,

8、 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 60, Sampling Freshly Mixed Concrete T 119M/T 119, Slump of Hydraulic Cement Concrete T 121M/T 121, Density (Unit Weight), Yield, and Air Content (Gravi

9、metric) of Concrete 2018 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-3b T 23-2 AASHTO T 152, Air Content of Freshly Mixed Concrete by the Pressure Method T 196M/T 196, Air Content of Freshly Mixed Con

10、crete by the Volumetric Method T 197M/T 197, Time of Setting of Concrete Mixtures by Penetration Resistance T 231, Capping Cylindrical Concrete Specimens T 309, Temperature of Freshly Mixed Portland Cement Concrete 2.2. ASTM Standard: C125, Standard Terminology Relating to Concrete and Concrete Aggr

11、egates 2.3. ACI Standard: ACI 309R, Guide for Consolidation of Concrete 3. TERMINOLOGY 3.1. For definitions of terms used in this practice, refer to ASTM C125. 4. SIGNIFICANCE AND USE 4.1. This method provides standardized requirements for making, curing, protecting, and transporting concrete test s

12、pecimens under field conditions. 4.2. If the specimens are made and standard cured, as stipulated herein, the resulting strength test data where the 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

13、mixture proportions for strength; 4.2.3. Quality control. 4.3. If the specimens are made and field cured, as stipulated herein, the resulting strength 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 bei

14、ng 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. 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, GeneralMold

15、s for specimens or fastenings thereto in contact with the concrete shall be made of steel, cast iron, or other nonabsorbent material, nonreactive with concrete containing portland or other hydraulic cements. Molds shall hold their dimensions and shape under conditions of use. Molds shall be watertig

16、ht 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 suitable sealant, such as heavy grease, modeling clay, or microcrystalline wax shall be used where necessary to prevent leakage through the joints. Positive me

17、ans shall be provided to hold base plates firmly to the 2018 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-3b T 23-3 AASHTO molds. Reusable molds shall be lightly coated with mineral oil or a suitable n

18、onreactive form release material before use. 5.2. CylinderMolds for casting concrete test specimens shall conform to the requirements of M 205M/M 205. 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 th

19、e 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. Maximum 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, or 1.6 mm (1/16

20、in.) for molds of smaller depth or breadth. Except for flexure specimens, molds shall not vary from the nominal length by more than 1.6 mm (1/16in.). Flexure molds shall not be shorter than 1.6 mm (1/16in.) of the required length (greater lengths are allowed). 5.4. Tamping RodsA round, smooth, strai

21、ght, steel rod with a diameter conforming to the requirements in Table 1. The length of the tamping rod shall be at least 100 mm (4 in.) greater than the depth of the mold in which rodding is being performed, but not greater than 600 mm (24 in.) in overall length (see Note 1). The rod shall have the

22、 tamping end or both ends rounded to a hemispherical tip of the same diameter as the rod. Note 1A rod length of 400 mm (16 in.) to 600 mm (24 in.) meets the requirements of the following: T 119M/T 119, T 121M/T 121, T 152, and T 196M/T 196. Table 1Tamping Rod Requirements Rod DimensionsaDiameter of

23、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 frequency shal

24、l be at least 9000 vibrations per minute (150 Hz) while the vibrator is operating in the concrete. The diameter of a round vibrator shall be no more than one fourth of the diameter of the cylinder mold or one fourth the width of the beam mold. Other shaped vibrators shall have a perimeter equivalent

25、 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 2For information on size and frequency of

26、 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. Placement ToolsOf a size large enough so that each amount of concrete obtained from the sampling receptac

27、le is representative and small enough so that concrete is not spilled during the placement of the mold. For placing concrete in a cylinder mold, the acceptable tool is a scoop. For placing concrete in a beam mold, either a shovel or scoop is permitted. 5.8. Finishing ToolsHandheld float or a trowel.

28、 2018 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-3b T 23-4 AASHTO 5.9. Slump ApparatusThe apparatus for measurement of slump shall conform to the requirements of T 119M/T 119. 5.10. Sampling Receptac

29、leThe receptacle shall be a suitable heavy gauge metal pan, wheelbarrow, or flat, clean, nonabsorbent mixing board of sufficient capacity to allow easy remixing of the entire sample with a shovel or trowel. 5.11. Air Content ApparatusThe apparatus for measuring air content shall conform to the requi

30、rements of T 196M/T 196 or T 152. 5.12. Temperature Measuring DevicesThe temperature measuring devices shall conform to the applicable requirements of T 309M/T 309. 6. TESTING REQUIREMENTS 6.1. Cylindrical SpecimensCompressive or splitting tensile strength specimens shall be cylinders cast and allow

31、ed to set in an upright position. The number and size of cylinders cast shall be as directed by the specifier of the tests. In addition, the length shall be twice the diameter, and the cylinder diameter shall be at least three times the nominal maximum size of the coarse aggregate. When the nominal

32、maximum size of the coarse aggregate exceeds 50 mm (2 in.), the concrete sample shall be treated by wet sieving through a 50-mm (2-in.) sieve as described in R 60. For acceptance testing for specified compressive strength, cylinders shall be 152 by 300 mm (6 by 12 in.) or 100 by 200 mm (4 by 8 in.)

33、(Note 3). Note 3When molds in SI units are required and not available, equivalent inch-pound unit size molds should be permitted. 6.2. Beam 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

34、than three times the depth as tested. The ratio of width to depth as molded shall not exceed 1.5. 6.2.1. The minimum cross-sectional dimension of the beam shall be as stated in Table 2. Unless otherwise specified by the specifier of the tests, the standard beam shall be 152 by 152 mm (6 by 6 in.) in

35、 cross section. Table 2Minimum Cross-Sectional Dimensions of Beams Nominal Maximum Aggregate Size (NMAS) Minimum Cross-Sectional Dimension 25 mm (1 in.) 100 by 100 mm (4 by 4 in.) 25 mm (1 in.) NMAS 50 mm (2 in.) 152 by 152 mm (6 by 6 in.) 6.2.2. When the nominal maximum size of the coarse aggregate

36、 exceeds 50 mm (2 in.), the concrete sample shall be treated by wet sieving through a 50-mm (2-in.) sieve as described in R 60. 6.2.3. The specifier of tests shall specify the specimen size and the number of specimens to be tested to obtain an average test result (Note 4 and Note 5). The same specim

37、en size shall be used when comparing results and for mixture qualification and acceptance testing. Note 4The modulus of rupture can be determined using different specimen sizes. However, measured modulus of rupture generally increases as specimen size decreases.2,3The strength ratio for beams of dif

38、ferent sizes depends primarily on the maximum size of aggregate.4Experimental data obtained in two different studies have shown that for maximum aggregate size between 19.0 and 25.0 mm (3/4and 1 in.), the ratio between the modulus of rupture determined with a 152 by 152 mm (6 by 6 in.) and a 100 by

39、100 mm (4 by 4 in.) may vary from 0.90 to 1.072for maximum aggregate size between 9.5 and 37.5 mm (3/8and 11/2in.), the ratio between the modulus of rupture 2018 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable l

40、aw.TS-3b T 23-5 AASHTO determined with a 152 by 152 mm (6 by 6 in.) and a 115 by 115 mm (4.5 by 4.5 in.) may vary from 0.86 to 1.00.3Note 5It has been shown that the variability of individual tests results increases as the specimen size decreases.2,3 7. SAMPLING CONCRETE 7.1. The samples used to fab

41、ricate test specimens under 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

42、 8.1. SlumpMeasure and record the slump of each batch of concrete, from which specimens are made, immediately after remixing in the receptacle as required in T 119M/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 perfo

43、rming the air content test shall not be used in fabricating test specimens. 8.3. TemperatureDetermine and record the temperature in accordance with T 309. Note 6Some specifications may require the measurement of the unit weight of concrete. The volume of concrete produced per batch may be desired on

44、 some projects. Also, additional 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,

45、 horizontal surface, free from vibration and other disturbances, at a place as near as practicable to the location where they are to be stored. 9.2. Casting CylindersSelect the proper tamping rod from Section 5.4 and Table 1 or the proper vibrator from Section 5.5. Determine the method of consolidat

46、ion from Table 3, unless another method is specified. If the method of consolidation is rodding, determine molding requirements from Table 4. If the method of consolidation is vibration, determine molding requirements from Table 5. Select a scoop of the size described in Section 5.7. While placing t

47、he concrete in the mold, move the scoop around the perimeter of the mold opening to ensure an even distribution of the concrete with minimal segregation. Each layer of concrete shall be consolidated as required. In placing the final layer, add the amount of concrete that will fill the mold after con

48、solidation. 9.2.1. Self-Consolidating ConcreteCast specimens as described in Section 9.2 without layers or consolidation. Table 3Method of Consolidation Requirements Slump, mm (in.) Method of Consolidation 25 mm (1 in.) Rodding or vibration 25 mm (1 in.) Vibration 2018 by the American Association of

49、 State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-3b T 23-6 AASHTO 9.3. Number of Casting BeamsSelect the proper tamping rod from Section 5.4 and Table 1 or the proper vibrator from Section 5.5. Determine the method of consolidation from Table 3, unless another method is specified. If the method of consolidation is rodding, determine molding requirements from Table 4. If the method of consolidation is vibration, determine molding requirements from Tabl