AASHTO T363-17 pdf free download

AASHTO T363-17 pdf free download.Evaluating Stress Development and Cracking Potential due to Restrained Volume Change Using a Dual Ring Test.
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 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 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 methodology 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土2°C until the appropriate age, at which time the temperature is reduced at a rate of 2°C/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 effects 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, 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 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 standard. 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 caution, especially in applications such as quality control and acceptance testing. 4.5. While the cracking test can evaluate a material’s 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 modulus, Poisson ‘s 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 Rings- -The standard restraining rings shall be made of a low thermal expansion iron- nickel alloy (Invar) as specified in ASTM F1684 or equivalent. The inner and outer rings shall have wall thicknesses of 19 mm土3 mm (0.75 in. 土0.12 in.), as provided by the specified dimensions in Table 1. The height of the rings shall be 76.2 mm士3 mm (3 in.士0.12 in.). The . inner and outer faces shall be round, true, seamless, and polished smooth.AASHTO T363-17  pdf download.