AASHTO T 363-2017 Standard Method of Test for Evaluating Stress Development and Cracking Potential due to Restrained Volume Change Using a Dual Ring Test.pdf
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1、Standard Method of Test for Evaluating Stress Development and Cracking Potential due to Restrained Volume Change Using a Dual Ring Test AASHTO Designation: T 363-171Technical Section: 3c, Hardened Concrete Release: Group 1 (April 2017) American Association of State Highway and Transportation Officia
2、ls 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-3c T 363-1 AASHTO Standard Method of Test for Evaluating Stress Development and Cracking Potential due to Restrained Volume Change Using a Dual Ring Test AASHTO Designation: T 363-171Technical Section: 3c, Hardened Concrete Releas
3、e: Group 1 (April 2017) 1. SCOPE 1.1. This test method covers the evaluation of stress development and cracking potential in concrete when volume changes caused by shrinkage and temperature changes are restrained. The procedure is comparative for the degree of restraint of the ring and is not intend
4、ed to determine the time of initial cracking of a concrete cast in any specific type of structure. 1.2. The values stated in SI units are to be regarded as the standard. 1.3. This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibili
5、ty 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 Standard: R 39, Making and Curing Concrete Test Specimens in the Laboratory 2.2. ASTM Standards: C305, Stan
6、dard Practice for Mechanical Mixing of Hydraulic Cement Pastes and Mortars of Plastic Consistency C403/C403M, Standard Test Method for Time of Setting of Concrete Mixtures by Penetration Resistance C1581/C1581M, Standard Test Method for Determining Age at Cracking and Induced Tensile Stress Characte
7、ristics of Mortar and Concrete under Restrained Shrinkage C1698, Standard Test Method for Autogenous Strain of Cement Paste and Mortar F1684, Standard Specification for Iron-Nickel and Iron-Nickel-Cobalt Alloys for Low Thermal Expansion Applications 2.3. Other Document: Schlitter, J. L., A. H. Sente
8、r, D. P. Bentz, T. Nantung, and W. J. Weiss. A Dual Concentric Ring Test for Evaluating Residual Stress Development due to Restrained Volume Change. In Journal of ASTM International, Vol. 7, No. 9, ASTM, West Conshohocken, PA, 2010. 2017 by the American Association of State Highway and Transportatio
9、n Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c T 363-2 AASHTO 3. SUMMARY OF TEST METHOD 3.1. This test method measures the strains developed in two concentric metal rings providing restraint to a concrete specimen undergoing volume change. The measured strains in
10、 the restraining rings are used to calculate the stress development in the concrete specimen. This enables the stress that develops due to restraint to be quantified along with an assessment of the cracking potential of the concrete mixture. 3.2. This test method utilizes restraining rings made of a
11、 low thermal expansion iron-nickel alloy (Invar), allowing for the temperature of the test to be varied, while the rings remain nominally volumetrically stable. The test equipment is enclosed in an insulated chamber, with the temperature being controlled throughout the entirety of the test. The meth
12、odology set forth in this standard is to utilize the thermal capabilities of the dual ring test to assess the potential for cracking at 2, 4, and 7 days of age. The temperature of the test specimen is held at a constant 23 2C until the appropriate age, at which time the temperature is reduced at a r
13、ate of 2C/h until cracking is induced. This temperature drop approach yields the remaining stress capacity of the concrete specimens at early ages, quantifying the potential for cracking in the specimen at the given ages. 4. SIGNIFICANCE AND USE 4.1. This test method is suitable for evaluating the e
14、ffects of material variations on the cracking potential of restrained mortar elements. These variations may include aggregate source, aggregate gradation, aggregate absorption, aggregate-paste bond, cement type, cement content, water content, supplementary cementitious materials, fiber reinforcement
15、, or chemical admixtures. 4.2. Actual cracking during service or construction is dependent upon many variables including degree of restraint, hydration effects of the cement, curing methods, and environmental factors. This method is useful for comparing the relative likelihood of early age cracking
16、and for aiding in the selection of appropriate mixture designs. This method may also be utilized to evaluate the effect of temperature change on the thermal stress development and cracking tendency. 4.3. The details of the test method apply to nominal dimensions of specimens as set forth in this sta
17、ndard. Other specimen geometries may be used, with appropriate changes being made to ensure an equivalent degree of restraint in the specimens. The pertinent calculations can be found in the reference listed in Section 2.3. 4.4. The numerical results from this test method must be interpreted with ca
18、ution, especially in applications such as quality control and acceptance testing. 4.5. While the cracking test can evaluate a materials propensity to crack, it should be noted that other concrete tests that may be related to cracking tendency are the compressive strength, tensile strength, elastic m
19、odulus, Poissons ratio, drying shrinkage, unrestrained linear autogenous strain according to ASTM C1698, the single restrained ring test according to ASTM C1581/C1581M, and creep/relaxation testing. 5. APPARATUS 5.1. Restraining RingsThe standard restraining rings shall be made of a low thermal expa
20、nsion iron-nickel alloy (Invar) as specified in ASTM F1684 or equivalent. The inner and outer rings shall have wall thicknesses of 19 mm 3 mm (0.75 in. 0.12 in.), as provided by the specified dimensions in Table 1. The height of the rings shall be 76.2 mm 3 mm (3 in. 0.12 in.). The inner and outer f
21、aces shall be round, true, seamless, and polished smooth. 2017 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3c T 363-3 AASHTO (a) (b) Figure 1Geometry of Dual Ring Test (a) and Dual Ring Test Setup in I
22、nsulating Chamber (b) (see reference listed in Section 2.3) Table 1Dimensions of Dual Ring Test Ring Face Radius (mm) RII146 3 RIC165 3 ROC203 3 ROO222 3 Note 1Bond low coefficient of thermal expansion type strain gauges at four equidistant, mid-height locations on both the interior of the inner rin
23、g and the exterior of the outer ring. 5.2. Data AcquisitionThe data acquisition unit shall be compatible with the strain instrumentation and automatically record each strain gauge independently at 5-min intervals. It is recommended that the system be capable of correction for thermal changes. 5.3. B
24、ase FormThe base form shall be nonabsorbent. Fabricate the base form of resin-coated or polyethylene-coated plywood to minimize frictional restraint of the concrete. 5.4. Insulating ChamberThe dual ring test setup shall be enclosed in an insulating chamber throughout the entirety of testing. The ins
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