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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Any such distinction is arbitrary, because the various types of voids intergrade in size, shape, and other characteristics.

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

Print and complete the following order form. 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 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. Time for Results Please contact a CTLGroup chemical services representative or Project Manager to discuss your individual project needs and testing response times.

A Modified Point Count: They are most common beneath horizontal reinforcing bars, pieces of coarse aggregate satm as channelways along their sides.

The usual cause is a weak cement-paste matrix. Juliano row Enviado por: 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. If you need more info or have any questions, please note the Lab ID number 56 and contact us at:.

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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. Individual sections should be as large as can be ground and examined with the available equipment. These data are used to calculate the air content and various parameters of the air-void system. The honey-combing that is a consequence of the failure to compact the concrete properly is one type of entrapped air void.

The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. For concrete with a relatively high air content usually over 7.

Spread the selected traverse length uniformly over the available surface so as to compensate for the heterogeneity of the concrete. Do not include scratched or broken portions of the surface in the analyzed area. B These numbers represent, respectively, the 1s and D2s limits as described in Practice C 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.

Individual reprints single or multiple copies of this standard may be obtained by contacting ASTM at the above address or at phonefaxor service astm. Provide at least the minimum area of finished surface given in Table 1 in each sample.

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. Privacy Policy Sensors Sitemap. asgm

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

Includes both point count and linear traverse data. Three procedures are described:.

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Work Item s – proposed revisions of this standard. Concrete and Concrete Aggregates and is the direct responsibility of Subcommittee C The honey-combing that is a consequence of the failure to compact the concrete properly is one type of entrapped air void 9, Such treatment should not be used without care and experimentation.

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. Paste content determinations were made by 13 operators representing 8 different laboratories.

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

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. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. They occur also immediately below surfaces that were compacted by finishing operations before the completion of bleeding.

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. The problem is manifested by the plucking of sand grains from the surface during the lapping, with consequent scratching of the surface, and by undercutting of the paste around the harder aggregate particles. For concrete with a relatively high air content usually over 7.