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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NOTE 3—Grit numbers of abrasives can denote slightly different particle sizes, depending on the manufacturer. When assessing strength problems it is helpful to comparatively analyze acceptable and low strength samples. The ratio of the volume of aggregate to the volume of paste in v457 original mix must be accurately known or estimated to permit the calculation of the air-void systems parameters from the microscopically determined paste-air ratio.

Because Procedure C requires darkening the paste and aggregate, its use must occur after other tests if the analyst is also gathering petrographic data in addition to the measurements described in this test method. Warning—If the specimen was sawn with a lubricant other than water, heating must be done so as to avoid inhaling the fumes and to preclude fire or explosion. Prepared sections of such concrete should include a maximum of the xstm fraction, so as to increase the number of counts on air voids or traverse across them.

Areas that are scratched or imperfect indicate the need for additional preparation; use special techniques if required see 8. Reports that do make such a distinction typically define entrapped air voids as being larger than 1 mm in at least one dimension being irregular in shape, or both.

Hence, substantial differences in spacing factor may be caused solely by sampling and between laboratory variation. A Includes determinations using both point count and linear traverse. Appraisal, John Wiley and Sons, Inc. A sample may be composed of any number of specimens.

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Reviews in Engineering Geology, Geol. Eleven were by point count and 2 by linear traverse procedures. Historical Version s – view previous versions of standard. aastm

ASTM CCM – 12 – Microscopical Determination of Parameters of the Air-Void

Do not include scratched or broken portions of the surface in the analyzed area. Concrete and Concrete Aggregates and is the direct responsibility of Subcommittee C Such compressive strength must be at least 28 MPa [ psi]. From time to time during lapping, and when changing to a finer abrasive and when lapping is complete, clean all surfaces of the specimen gently and thoroughly to remove the grinding compound.

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 the c4577 data is gathered.

C39M – 16 – Compressive Strength of Cylindrical They are significant only in mixtures that contained excessive mixing water or in which pronounced bleeding and aatm occurred.

Three procedures are described:. 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.

However, significant differences may be observed if the sample of fresh concrete is consolidated to a different degree than the specimen later examined microscopically.

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

Additionally, this test method can be used for concrete product and mixture development requiring resistance of the concrete against freezing and thawing damage. The most common examples are concrete with large coarse aggregate and samples from the finished surface region, for both of which the examined sample consists of a disproportionately large amount of the mortar fraction. ProceedingsHighway Research Board, Vol 29,p. The ratio of the volume of aggregate to the volume of paste in the original mix must be accurately known or estimated to permit the calculation of the air-void systems parameters from the microscopically determined paste-air ratio.

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The usual cause is a weak cement-paste matrix. The following text provides useful information on air-void system parameters of known freeze-thaw durable concrete and explains guidelines and specifications from other respected specifying agencies.

Cleaning with a soft cosmetic brush under running water, or by a pressurized dental spray has been successful. B These numbers represent, respectively, the 1s and D2s limits as described in Practice C For concrete with a relatively high air content usually over 7.

A superscript epsilon indicates an editorial change since the last revision or reapproval.

NOTE 2—Apparatus for measurement of prepared samples is described in the two following procedures. Use The test is a quantitative method that measures the air-void content and other air-void system parameters in hardened concrete.

A watervoid is usually identified by its irregular shape or evidence that a channel or cavity has been created by bleed water trapped in the concrete at the time it hardened.

BoxFarmington Hills, MIhttp: The selection of which one of the three methods to be used shall be subject to agreement of the user and provider of the determination Note 1: Includes both point count and linear traverse data.

They occur also immediately below surfaces that were compacted by finishing operations before the completion of bleeding. They are significant only in mixtures that contained excessive mixing water or in which pronounced bleeding and settlement occurred. ASTM C, petrographic examination of concrete.

Air Void Testing for Concrete, ASTM C

The CTLGroup contacts can assist with questions about sample size and number of samples. These points may be in one or more planes intersecting the sample. The suggested sizes will usually be appropriate, but asmt may be selected according to the experience of the user.

No further reproductions authorized. A number in parentheses indicates the year of last reapproval.