1、Standard Method of Test for Resistance of Concrete to Rapid Freezing and Thawing AASHTO Designation: T 161-17 Technical Section: 3c, Hardened Concrete Release: Group 1 (April 2017) ASTM Designation: C666/C666M-15 American Association of State Highway and Transportation Officials 444 North Capitol St
2、reet N.W., Suite 249 Washington, D.C. 20001 TS-3c T 161-1 AASHTO Standard Method of Test for Resistance of Concrete to Rapid Freezing and Thawing AASHTO Designation: T 161-17 Technical Section: 3c, Hardened Concrete Release: Group 1 (April 2017) ASTM Designation: C666/C666M-15 1. SCOPE 1.1. This met
3、hod covers the determination of the resistance of concrete specimens to rapidly repeated cycles of freezing and thawing in the 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 in
4、tended for use in determining the effects of variations in the properties of concrete on the resistance of the concrete to the 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 expec
5、ted from a specific type of concrete. 1.2. 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 exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two system
6、s may result in nonconformance with the standard. 1.3. All material in this 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 res
7、ponsibility of the user of this standard to establish appropriate safety 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 D
8、etermination of Length Change of Hardened Cement Paste, Mortar, and Concrete R 39, Making and Curing Concrete Test Specimens in the Laboratory T 157, Air-Entraining Admixtures for Concrete 2.2. ASTM Standards: C215, Standard Test Method for Fundamental Transverse, Longitudinal, and Torsional Frequen
9、cies of Concrete Specimens C295/C295M, Standard Guide for Petrographic Examination of Aggregates for 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 161-2 AASHTO C341/C341M, Standard Pra
10、ctice for Length Change of Cast, Drilled, or Sawed Specimens of Hydraulic-Cement Mortar and Concrete C670, Standard Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials C823/C823M, Standard Practice for Examination and Sampling of Hardened Concrete in Cons
11、tructions STP169C, Significance of Tests and Properties of Concrete and Concrete-Making Materials STP169D, Significance of Tests and Properties of Concrete and Concrete-Making Materials 3. SIGNIFICANCE AND USE 3.1. As noted in the scope, the two procedures described in this method are intended to de
12、termine the effects of variations in both properties and conditioning of concrete in the resistance to freezing and thawing cycles specified in the particular procedure. Specific applications include specified use in M 194M/M 194, T 157, and ranking of coarse aggregates as to their effect on concret
13、e 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 frost-resistant concrete that may be defined as (1) any concrete not critically saturated with water (that is, not sufficiently
14、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 and thus will prevent critical saturation by water under common conditions. 3.3. If, as a result of performance tests as described
15、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 air-void system, and allowed to mature properly. 3.4. No relationship has been established between the resistance to cycles of fr
16、eezing and thawing of specimens cut from hardened concrete and specimens prepared in the laboratory. 3.5. There is no specific guidance on choosing between Procedure A and Procedure B for a given application, except when contained in a standard. Standards T 157 and M 194M/M 194 both stipulate Proced
17、ure A. 3.5.1. In many instances, the choice is based on the users determination of suitability to a specific application. 3.5.1.1. Procedure A is generally considered to be more aggressive of the two and to better reveal defective materials, although some consider the constant saturation of the test
18、 specimens to be unrealistic. 3.5.1.2. Some users prefer Procedure B as being more representative of the saturation patterns in some field applications. 3.5.2. A more complete discussion of the significance and use can be found in ASTM STP169C and STP169D. 2017 by the American Association of State H
19、ighway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c T 161-3 AASHTO 4. APPARATUS 4.1. Freezing and Thawing Apparatus: 4.1.1. The freezing and thawing apparatus shall consist of a suitable chamber or chambers in which the specimens may be subject
20、ed to the specified freezing and thawing cycle, together with the necessary refrigerating and heating equipment and controls to produce, continuously and automatically, reproducible cycles within the specified temperature requirements. In the event that the equipment does not operate automatically,
21、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. 4.1.2. The apparatus shall be so arranged that, except for necessary supports, each specimen is: (1) for Proce
22、dure 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 B, completely surrounded by air during the freezing phase of the cycle and by water during the thawing phas
23、e. 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 studs. Note 1Experience has indicated that ice or water pressure, during freezing tests, particularly in eq
24、uipment 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 bulging or other distortion of containers occurs should be interpreted with caution. 4.1.3. The temperatur
25、e 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 container for Procedure A or on the surface of any specimen for Procedure B, except during the transition between freezing and
26、thawing and vice versa. 4.1.3.1. 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 conditi
27、ons substantially different 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 support
28、s on which the specimens rest 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,
29、 metal rods, or the edges of 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 thermocou
30、ples, capable of measuring 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 C215. 4.4. Optional Length Change Test Length, Change ComparatorConforming to the r
31、equirements of M 210M/M 210. When specimens longer than the nominal 285-mm (111/4-in.) length provided for in M 210M/M 210 are used for freezethaw tests, use an appropriate length reference bar, which otherwise meets the M 210M/M 210 requirements. Dial gauge micrometers for use on these longer 2017
32、by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c T 161-4 AASHTO length change comparators shall meet the gradation interval and accuracy requirements for M 210M/M 210 for the millimeter (inch) calibratio
33、n 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. ScalesWith a capacity approximately 50 percent greater than the weight of the specimens and accurate to at leas
34、t 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 in water, such that when removed from the tank and tested for fundamental transverse frequency and length chan
35、ge, 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 the specimen chamber in the freezing and thawing apparatus by stopping the apparatus at the end of the thawing
36、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 range. It is required that the same target specimen thaw temperature be used throughout the testing of an individ
37、ual 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 with the requirements for the freezing and thawing cycle on temperature measurements of control specimens of
38、 similar concrete to the specimens under test in which suitable temperature-measuring devices have been imbedded. Change the position of these control specimens frequently in such a way as to indicate the extremes of temperature variation at different locations in the specimen cabinet. 5.2. The nomi
39、nal freezing and thawing 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
40、be used for thawing, and 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
41、 no specimen at any time 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 fo
42、r the temperature at the 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 (3
43、5 to 10F) shall not differ 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
44、 period from the time required 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 spe
45、cimens can be used to fill 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 th
46、e same time, may not permit 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. 2017 by the American Association of State Highway and Transportation Officials.All
47、 rights reserved. Duplication is a violation of applicable law.TS-3c T 161-5 AASHTO 5.3. The difference between the temperature at the center of a specimen and the temperature at its surface shall at no time exceed 28C (50F). 5.4. The period of transition between the freezing and thawing phases of t
48、he 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 shall be sampled using applicable standard methods. 6.2. Samples cut from hardened concrete are to be obtained
49、 in accordance with ASTM C823/C823M. 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 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 specimens should n
