AASHTO T 161-2008 Standard Method of Test for Resistance of Concrete to Rapid Freezing and Thawing《混凝土快冻和快消耐受性的标准试验方法》.pdf

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1、Standard Method of Test for Resistance of Concrete to Rapid Freezing and Thawing AASHTO Designation: T 161-08 (2012) ASTM Designation: C 666/C 666M-03 American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-3c T 161-1 AASH

2、TO Standard Method of Test for Resistance of Concrete to Rapid Freezing and Thawing AASHTO Designation: T 161-08 (2012) ASTM Designation: C 666/C 666M-03 1. SCOPE 1.1. This method covers the determination of the resistance of concrete specimens to rapidly repeated cycles of freezing and thawing in t

3、he laboratory by two different procedures: Procedure A, Rapid Freezing and Thawing in Water, and Procedure B, Rapid Freezing in Air and Thawing in Water. Both procedures are intended for use in determining the effects of variations in the properties of concrete on the resistance of the concrete to t

4、he freezing and thawing cycles specified in the particular procedure. Neither procedure is intended to provide a quantitative measure of the length of service that may be expected from a specific type of concrete. 1.2. The values stated in SI units are the preferred standard. 1.3. All material in th

5、is test method not specifically designated as belonging to Procedure A or Procedure B applies to either procedure. 1.4. This standard does not purport to address all of the safety concerns associated with its use. It is the responsibility of the user of this standard to establish appropriate safety

6、and health practices and determine the applicability of regulatory limitations prior to use. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: M 194M/M 194, Chemical Admixtures for Concrete M 210M/M 210, Use of Apparatus for the Determination of Length Change of Hardened Cement Paste, Mortar, and Concr

7、ete R 39, Making and Curing Concrete Test Specimens in the Laboratory T 157, Air-Entraining Admixtures for Concrete T 160, Length Change of Hardened Hydraulic Cement Mortar and Concrete 2.2. ASTM Standards: C 215, Standard Test Method for Fundamental Transverse, Longitudinal, and Torsional Frequenci

8、es of Concrete Specimens C 295/C 295M, Standard Guide for Petrographic Examination of Aggregates for Concrete C 341/C 341M, Standard Practice for Length Change of Cast, Drilled, or Sawed Specimens of Hydraulic-Cement Mortar and Concrete 2014 by the American Association of State Highway and Transport

9、ation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c T 161-2 AASHTO C 670, Standard Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials C 823/C 823M, Standard Practice for Examination and Sampling of Hardened Concrete in

10、 Constructions 3. SIGNIFICANCE AND USE 3.1. As noted in the scope, the two procedures described in this method are intended to determine the effects of variations in both properties and conditioning of concrete in the resistance to freezing and thawing cycles specified in the particular procedure. S

11、pecific applications include specified use in M 194M/M 194, T 157, and ranking of coarse aggregates as to their effect on concrete freezethaw durability, especially where soundness of the aggregate is questionable. 3.2. It is assumed that the procedures will have no significantly damaging effects on

12、 frost-resistant concrete that may be defined as (1) any concrete not critically saturated with water (that is, not sufficiently saturated to be damaged by freezing) and (2) concrete made with frost-resistant aggregates and having an adequate air-void system that has achieved appropriate maturity an

13、d thus will prevent critical saturation by water under common conditions. 3.3. If, as a result of performance tests as described in this method, concrete is found to be relatively unaffected, it can be assumed that it was either not critically saturated or was made with “sound” aggregates, a proper

14、air-void system, and allowed to mature properly. 3.4. No relationship has been established between the resistance to cycles of freezing and thawing of specimens cut from hardened concrete and specimens prepared in the laboratory. 4. APPARATUS 4.1. Freezing and Thawing Apparatus: 4.1.1. The freezing

15、and thawing apparatus shall consist of a suitable chamber or chambers in which the specimens may be subjected to the specified freezing and thawing cycle, together with the necessary refrigerating and heating equipment and controls to produce, continuously and automatically, reproducible cycles with

16、in the specified temperature requirements. In the event that the equipment does not operate automatically, provision shall be made for either its continuous manual operation on a 24-hour-a-day basis or for the storage of all specimens in a frozen condition when the equipment is not in operation. 4.1

17、.2. The apparatus shall be so arranged that, except for necessary supports, each specimen is: (1) for Procedure A, completely surrounded by not less than 1 mm (1/32in.) nor more than 3 mm (1/8in.) of water at all times while it is being subjected to freezing and thawing cycles, or (2) for Procedure

18、B, completely surrounded by air during the freezing phase of the cycle and by water during the thawing phase. Rigid containers, which have the potential to damage specimens, are not permitted. Length change specimens in vertical containers shall be supported in a manner to avoid damage to the gauge

19、studs. Note 1Experience has indicated that ice or water pressure, during freezing tests, particularly in equipment that uses air rather than a liquid as the heat transfer medium, can cause excessive damage to rigid metal containers and possibly to the specimens therein. Results of tests during which

20、 bulging or other distortion of containers occurs should be interpreted with caution. 4.1.3. The temperature of the heat-exchanging medium shall be uniform within 3C (6F) throughout the specimen cabinet when measured at any given time, at any point on the surface of any specimen 2014 by the American

21、 Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c T 161-3 AASHTO container for Procedure A or on the surface of any specimen for Procedure B, except during the transition between freezing and thawing and vice versa. 4.1

22、.3.1. Support each specimen at the bottom of its container in such a way that the temperature of the heat-exchanging medium will not be transmitted directly through the bottom of the container to the full area of the bottom of the specimen, thereby subjecting it to conditions substantially different

23、 from the remainder of the specimen. Note 2A flat spiral of 3-mm (1/8-in.) wire placed in the bottom of the container has been found adequate for supporting specimens. 4.1.4. For Procedure B, it is not contemplated that the specimens will be kept in containers. The supports on which the specimens re

24、st shall be such that they are not in contact with the full area of the supported side or end of the specimen, thereby subjecting this area to conditions substantially different from those imposed on the remainder of the specimen. Note 3The use of relatively open gratings, metal rods, or the edges o

25、f metal angles has been found adequate for supporting specimens, provided the heat-exchanging medium can circulate in the direction of the long axis of the rods or angles. 4.2. Temperature-Measuring Equipmentconsisting of thermometers, resistance thermometers, or thermocouples, capable of measuring

26、the temperature at various points within the specimen chamber and at the centers of control specimens to within 1C (2F). 4.3. Dynamic Testing Apparatusconforming to the requirements of ASTM C 215. 4.4. Optional Length Change Test Length, Change Comparatorconforming to the requirements of M 210M/M 21

27、0. When specimens longer than the nominal 285-mm (111/4-in.) length provided for in M 210M/M 210 are used for freeze-thaw tests, use an appropriate length reference bar, which otherwise meets the M 210M/M 210 requirements. Dial gauge micrometers for use on these longer length change comparators shal

28、l meet the gradation interval and accuracy requirements for M 210M/M 210 for the millimeter (inch) calibration requirements. Prior to the start of measurements on any specimens, fix the comparator at an appropriate length to accommodate all of the specimens to be monitored for length change. 4.5. Sc

29、aleswith a capacity approximately 50 percent greater than the weight of the specimens and accurate to at least 5 g (0.01 lb) within the range of 10 percent of the specimen weight will be satisfactory. 4.6. Tempering Tankwith suitable provisions for maintaining the temperature of the test specimens i

30、n water, such that when removed from the tank and tested for fundamental transverse frequency and length change, the specimens will be maintained within 1 and +2C (2 and +4F) of the target thaw temperature for specimens in the actual freezing and thawing cycle and equipment being used. The use of th

31、e specimen chamber in the freezing and thawing apparatus by stopping the apparatus at the end of the thawing cycle and holding the specimens in it shall be considered as meeting this requirement, provided the specimens are tested for fundamental transverse frequency within the above temperature rang

32、e. It is required that the same target specimen thaw temperature be used throughout the testing of an individual specimen because a change in specimen temperature at the time of length measurement can affect the length of the specimen significantly. 5. FREEZING AND THAWING CYCLE 5.1. Base conformity

33、 with the requirements for the freezing and thawing cycle on temperature measurements of control specimens of similar concrete to the specimens under test in which suitable temperature-measuring devices have been imbedded. Change the position of these control 2014 by the American Association of Stat

34、e Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c T 161-4 AASHTO specimens frequently in such a way as to indicate the extremes of temperature variation at different locations in the specimen cabinet. 5.2. The nominal freezing and thawing

35、cycle for both procedures of this method shall consist of alternately lowering the temperature of the specimens from 4 to 18C (40 to 0F) and raising it from 18 to 4C (0 to 40F) in not less than 2 nor more than 5 h. For Procedure A, not less than 25 percent of the time shall be used for thawing, and

36、for Procedure B, not less than 20 percent of the time shall be used for thawing (Note 4). At the end of the cooling period, the temperature at the centers of the specimens shall be 18 2C (0 3F), and at the end of the heating period the temperature shall be 4 2C (40 3F), with no specimen at any time

37、reaching a temperature lower than 20C (3F) nor higher than 6C (43F). The time required for the temperature at the center of any single specimen to be reduced from 3 to 16C (37 to 3F) shall be no less than one-half of the length of the cooling period, and the time required for the temperature at the

38、center of any single specimen to be raised from 16 to 3C (3 to 37F) shall be not less than one-half of the length of the heating period. For specimens to be compared with each other, the time required to change the temperature at the centers of any specimens from 2 to 12C (35 to 10F) shall not diffe

39、r by more than one-sixth of the length of the cooling period from the time required for any specimen and the time required to change the temperature at the centers of any specimens from 12 to 2C (10 to 35F) shall not differ by more than one-third of the length of the heating period from the time req

40、uired for any specimen. Note 4In most cases, uniform temperature and time conditions can be controlled most conveniently by maintaining a capacity load of specimens in the equipment at all times. In the event that a capacity load of test specimens is not available, dummy specimens can be used to fil

41、l empty spaces. This procedure also assists greatly in maintaining uniform fluid level conditions in the specimen and solution tanks. The testing of concrete specimens composed of widely varying materials or with widely varying thermal properties, in the same equipment at the same time, may not perm

42、it adherence to the time-temperature requirements for all specimens. It is advisable that such specimens be tested at different times and that appropriate adjustments be made to the equipment. 5.3. The difference between the temperature at the center of a specimen and the temperature at its surface

43、shall at no time exceed 28C (50F). 5.4. The period of transition between the freezing and thawing phases of the cycle shall not exceed 10 min, except when specimens are being tested in accordance with Section 8.3. 6. SAMPLING 6.1. Constituent materials for concrete specimens made in the laboratory s

44、hall be sampled using applicable standard methods. 6.2. Samples cut from hardened concrete are to be obtained in accordance with ASTM C 823/C 823M. 7. TEST SPECIMENS 7.1. The specimens for use in this test shall be prisms or cylinders made and cured in accordance with the applicable requirements of

45、M 210M/M 210 and R 39. 7.2. Specimens used shall not be less than 75 mm (3 in.) nor more than 125 mm (5 in.) in width, depth, or diameter, and not less than 275 mm (11 in.) nor more than 405 mm (16 in.) in length. 7.3. Test specimens may also be cores or prisms cut from hardened concrete. If so, the

46、 specimens should not be allowed to dry to a moisture condition below that of the structure from which they 2014 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c T 161-5 AASHTO were taken. This may be ac

47、complished by wrapping in plastic or by other suitable means. The specimens so obtained shall be furnished with gauge studs in accordance with ASTM C 341/C 341M. 7.4. For this test the specimens shall be stored in saturated lime water from the time of their removal from the molds until the time free

48、zing and thawing tests are started. All specimens to be compared with each other initially shall be of the same nominal dimensions. 8. PROCEDURE 8.1. Molded beam specimens shall be cured for 14 days prior to testing unless otherwise specified. Beam specimens sawed from hardened concrete shall be moi

49、sture-conditioned by immersing in saturated lime water at 23 2C (73 3F) for 48 h prior to testing unless otherwise specified. 8.2. Immediately after the specified curing or conditioning period, bring the specimen to a temperature within 1 and +2C (2 and +4F) of the target thaw temperature that will be used in the freeze-thaw cycle and test for fundamental transverse frequency, determine the mass, determine the average length and cross-section dimensions of the concrete specimen within the toler