ASTM C457 PDF

Baixe grátis o arquivo ASTM CCM – 12 _ Microscopical Determination of Parameters of the Air-Void System in Hardened Concrete (2).pdf enviado por. This standard is issued under the fixed designation C ; the number concrete. 1 This practice is under the jurisdiction of ASTM Committee C-9 on Concrete. Humboldt’s Linear Traverse Machine for concrete air void testing facilitates the counting of microscopic voids in concrete. Meets or exceeds ASTM C

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C39M – 16 – Compressive Strength of Cylindrical They are most common beneath horizontal reinforcing bars, pieces of coarse aggregate and as channelways along their sides. A superscript epsilon indicates an editorial change since the last revision or reapproval. Warning—If the specimen was sawn with a lubricant other than water, heating must be ashm so as to avoid inhaling the fumes and to preclude fire or explosion.

ASTM C Microscopical Determination of the Air-Void System | CTL Grp

Somewhat larger values may be adequate for mild exposure, and smaller ones may be required for severe exposure, especially if the concrete is in contact with deicing chemicals. They are significant only in mixtures that contained excessive mixing water or in which pronounced bleeding and settlement occurred. These data are used to calculate the air content and various parameters of the air-void system.

The data gathered are the linear distance between stops along the traverse Ithe total number of stops Stthe number of stops in air voids Sathe number of stops in paste Spand the number of air voids N intersected by the line of traverse over which c47 component data is gathered.

No further reproductions authorized. Concrete and Concrete Aggregates and is the direct responsibility of Subcommittee C ASTM C, petrographic examination of concrete.

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If only the air content is desired, only Ta and Tt need be determined. An increase in the water-cement ratio or the paste content must be accompanied by an increase in the air content, if the spacing factor.

In such instances the following procedure is helpful. Combining values from the two systems may result in non-conformance with the standard.

These points may be in one or more planes intersecting the sample. Juliano row Enviado por: Instructions A 3 to 4- inch diameter core, about 4 to 6 inches long is typically needed to process a sufficient test area in accordance with the test method, depending on the top size of the aggregate.

The selection of which one of the three methods to be used shall atm subject to agreement of the user and provider of the determination Note 1: A Includes all data—all labs and all operators. Any such distinction is arbitrary, because the various types of voids intergrade in size, shape, and other characteristics. Appraisal, John Wiley and Sons, Inc.

ASTM C457.C457M – 12 – Microscopical Determination of Parameters of the Air-Void…

Link to Active This link will always route to the current Active version of the standard. However, significant differences may be observed if the sample of fresh concrete is consolidated to a different degree than the sample later examined microscopically. If scaling and suspected freeze-thaw distress is c4577 issue, or if delamination is the suspected problem, the samples need to contain the finished top surface.

Eleven were by point count and 2 by linear traverse procedures. However, significant differences may be observed if the sample of fresh concrete is consolidated to a different degree than the specimen later examined microscopically. The factors affecting the variability of the test method are discussed in the section on Precision and Bias. The required area may consist of more than one prepared section. The honey-combing that is a consequence of the failure to compact the concrete properly is one type of entrapped air void.

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The honey-combing that is a consequence of the failure to compact the concrete properly is one type of entrapped air void 9, Open Cup Tester 2. A surface that is satisfactory for microscopical examination will show an excellent reflection of a distant light source when viewed at a low incident angle and there shall be no noticeable relief between the paste and the aggregate surfaces.

Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. Hence, this test method can be used to develop data to estimate the likelihood of damage due to cyclic freezing and thawing or to explain why it has occurred.

Use of ultrasonic cleaners may be harmful to the surface.

NOTE 1—The air-void content determined in accordance with this test. Results can also be applied to other situations in which the air content of concrete is in question. To convert to units of percent air content, divide by n and multiply by to get percent. Juliano row Enviado por: The test method can also be used as an adjunct to the development aastm products or procedures intended to enhance the resistance of concrete to cyclic freezing and thawing.

Originally approved in Work Item s – proposed revisions of this standard. Individual sections should be as large as can be ground and examined with the available equipment.