1、Standard Method of Test for Making and Curing Concrete Test Specimens in the Field AASHTO Designation: T 23-171Technical Section: 3c, Hardened Concrete Release: Group 1 (April 2017) ASTM Designation: C31-15a American Association of State Highway and Transportation Officials 444 North Capitol Street
2、N.W., Suite 249 Washington, D.C. 20001 TS-3c T 23-1 AASHTO Standard Method of Test for Making and Curing Concrete Test Specimens in the Field AASHTO Designation: T 23-171Technical Section: 3c, Hardened Concrete Release: Group 1 (April 2017) ASTM Designation: C31-15a 1. SCOPE 1.1. This method covers
3、procedures for making 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
4、of mix water and 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 s
5、ystem may not be 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
6、 the responsibility of the user of this standard to establish appropriate safety and 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 prolonge
7、d exposure. 1.5. 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
8、, 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 60, Sampling Freshly Mixed Concrete T 119M/T 119, Slump of Hydraulic Cement Concrete T 121M/T 121, Density (Unit Weight), Yield, and Air
9、Content (Gravimetric) of Concrete 2017 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c T 23-2 AASHTO T 152, Air Content of Freshly Mixed Concrete by the Pressure Method T 196M/T 196, Air Content of Fres
10、hly Mixed Concrete 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
11、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 to ASTM C125. 4. SIGNIFICANCE AND USE 4.1. This method provides standardized requirements for making, curing, protecting, and transporting co
12、ncrete test specimens 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
13、 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 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 c
14、apable 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. 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
15、, GeneralMolds 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 shal
16、l 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 suitable sealant, such as heavy grease, modeling clay, or microcrystalline wax shall be used where necessary to prevent leakage through the joints
17、. Positive means shall be provided to hold base plates firmly to the 2017 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 molds. Reusable molds shall be lightly coated with mineral oil or
18、a suitable nonreactive 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 su
19、rfaces 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. 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. Mol
20、ds shall produce specimens not more than 1.6 mm (1/16in.) shorter than the required length in accordance with Section 6.2. 5.4. Tamping Rods A round, smooth, straight, 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.)
21、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 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
22、 (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 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
23、) 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 shall be at least 9000 vibrations per minute (150 Hz) while the vibrator is operating in the concrete. The diameter of a round vibrator shall
24、 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 to the circumference of an appropriate round vibrator. The combined length of the vibrator shaft and vibrating element shall exceed the
25、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 various vibrators and a method to periodically check vibrator frequency, see ACI 309R. 5.6. MalletA mallet with a rubber or rawhide head
26、 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 receptacle is representative and small enough so that concrete is not spilled during the placement of the mold. For placing concrete in a cylinde
27、r 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. 5.9. Slump ApparatusThe apparatus for measurement of slump shall conform to the requirements of T 119M/T 119. 2017 by the American Assoc
28、iation of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c T 23-4 AASHTO 5.10. Sampling ReceptacleThe receptacle shall be a suitable heavy gauge metal pan, wheelbarrow, or flat, clean, nonabsorbent mixing board of sufficient capacity
29、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 requirements of T 196M/T 196 or T 152. 5.12. Temperature Measuring DevicesThe temperature measuring devices shall conform to the applicable req
30、uirements of T 309M/T 309. 6. TESTING REQUIREMENTS 6.1. Cylindrical SpecimensCompressive or splitting tensile strength specimens shall be cylinders cast and allowed 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, t
31、he 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 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.) si
32、eve 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.) (Note 3). Note 3When molds in SI units are required and not available, equivalent inch-pound unit size molds should be permitted. 6.2. Bea
33、m 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. The ratio of width to depth as molded shall not exceed 1.5. 6.2.1. The minimum cross-sectional dimen
34、sion 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 cross section. Table 2Minimum Cross-Sectional Dimensions of Beams Nominal Maximum Aggregate Size (NMAS) Minimum Cross-Sectional Dimension
35、 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 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
36、 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 specimen size shall be used when comparing results and for mixture qualification and acceptance testing. Note 4The modulus of rupture can be det
37、ermined using different specimen sizes. However, measured modulus of rupture generally increases as specimen size decreases.2,3The strength ratio for beams of different sizes depends primarily on the maximum size of aggregate.4Experimental data obtained in two different studies have shown that for m
38、aximum 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 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
39、modulus of rupture 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 1.00.3 2017 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 Note
40、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 fabricate test specimens under this standard shall be obtained in accordance with R 60 unless an alternative procedure has been approved. 7.2
41、. 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 record the slump of each batch of concrete, from which specimens are made, immediately after remixing in the recept
42、acle 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 performing the air content test shall not be used in fabricating test specimens. 8.3. TemperatureDetermine and record the temperature in accord
43、ance 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 some projects. Also, additional information on the air content measurements may be desired. Test Method T 121M/T 121 is used to measure t
44、he 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 from vibration and other disturbances, at a place as near as practicable to the location where they are to be st
45、ored. 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 consolidation from Table 3, unless another method is specified. If the method of consolidation is rodding, determine molding requirements from Table
46、 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 the concrete in the mold, move the scoop around the perimeter of the mold opening to ensure an even distribution of the concrete with minim
47、al 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 consolidation. 9.2.1. Self-Consolidating ConcreteCast specimens as described in Section 9.2 without layers or consolidation. Table 3Method of
48、 Consolidation Requirements Slump, mm (in.) Method of Consolidation 25 mm (1 in.) Rodding or vibration 25 mm (1 in.) Vibration 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 Ta
49、ble 3, unless another method is specified. If the method of consolidation is rodding, determine molding 2017 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c T 23-6 AASHTO requirements from Table 4. If the method of consolidation is vibration, determine molding requirements from Table 5. Determine the number of roddings per layer, one for each 14 cm2(2 in.2) of the top surface area of the beam. Select a placement tool as
