ASTM C457 PDF

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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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If only the air content is desired, only Sa and St need be determined. Use The test is a quantitative method that measures aztm air-void content and other air-void system parameters in hardened concrete.

B Theoretical Standard Deviation: For voids per in.: They are most common beneath horizontal reinforcing bars, pieces of coarse aggregate and as channelways along their sides. They occur also immediately below surfaces that were compacted by finishing operations before the completion of bleeding.

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

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. NOTE 2—Apparatus for measurement of prepared samples is described in the two following procedures. 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. A Includes determinations using both point count and linear traverse.

This standard is subject asgm revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn. For concrete with a relatively high air content usually over 7. For specific hazard statements see Note 9 and Note They are significant only in mixtures that contained excessive mixing water or in which pronounced bleeding and settlement occurred.

They occur also immediately below surfaces that were compacted by finishing operations before the completion of bleeding.

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Any such distinction is arbitrary, because the various types of voids intergrade in size, shape, and other characteristics. Results can also aetm applied 4c57 other situations in which the air content of concrete is in question.

Reviews in Atm Geology, Geol.

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

BoxFarmington Hills, MIhttp: If scaling and suspected freeze-thaw distress is the issue, or if delamination is the suspected problem, the samples need to contain the finished top surface. Combining values from the two systems may result in non-conformance with the standard. The parameters determined by this procedure are most often related to atsm susceptibility of the concrete to freezing and thawing damage.

No further reproductions authorized. C39M – 16 – Compressive Strength of Cylindrical Lap the surface with successively finer abrasives until it is suitable for microscopical observation.

The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Paste content determinations were made by 13 operators ashm 8 different laboratories. For specific hazard statements see 8.

If only the air content is desired, only Ta and Tt need be determined. The CTLGroup contacts can assist with questions about sample size and number of samples. ProceedingsHighway Research Board, Vol 29,p.

Link to Active This link will always route to the current Active version of the standard. Three procedures are described:.

Consequently, utmost care must be taken in conducting either microscopical method to observe and record. To convert to units of percent air content, divide by n and multiply by to get percent. Reports that do make such a distinction typically cc457 entrapped air voids as being larger than 1 m in at least one dimension being irregular in shape, or both.

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 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: The honey-combing that is a consequence of the failure to compact the concrete properly is one type of entrapped air void 9, Prepared sections of such concrete should include a maximum of the mortar fraction, so as to increase the number of counts on air voids or traverse across them.

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They are significant only in mixtures that contained excessive mixing water or in which pronounced bleeding and settlement occurred. Areas that are scratched or imperfect indicate the need for additional preparation; use special techniques if required see 8. 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 usual procedure must be changed, and the paste-air ratio modification must be used see 5. Any such adtm is arbitrary, because the various types of voids intergrade qstm size, shape, and other characteristics.

Air Void Testing for Concrete, ASTM C

These data are used to calculate the air content and various parameters of the air-void system. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. The test method can also be used as an adjunct to the development of products or procedures intended to enhance the resistance of concrete to cyclic freezing and thawing.

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.

Historical Version s – view previous versions of standard. Cleaning with a soft cosmetic brush under running water, or by a pressurized dental spray has been successful. When assessing strength problems it is helpful to comparatively analyze acceptable and low strength samples.