Masters Theses

Ugur Ozoguz

Abstract

"This study, entitled "Properties of Air-Entrained Concrete at Early Ages" concerns a group of tests designed to provide quantitative information regarding the effect of entrained air on the strength and durability of concrete before it reaches its 28 day strength.

Experiences in the field and laboratories have demonstrated that the addition of a moderate amount of air to any concrete mix will bring a marked increase in resistance to the disintegrating effects of freezing and thawing.

There have been extensive studies made on the subject of durability of air entrained concrete. Most of these studies were based on the effect of freezing and thawing action after the specimens had been cured for a period of 28 days. According to ASTM the standard procedure is to remove the specimens from the curing room and begin freeze-thaw tests at 14 days unless otherwise specified. These recommendations have not been adhered to in very many cases.

In 1946, Charles E. Wuerpel published the results of a series of tests in which specimens were subjected to freezing and thawing after 16 days of curing. This series of tests was designed to investigate the relative effects of nine different air-entraining admixtures in concrete. Another freeze-thaw series was performed on specimens cured for nine days. The object of these tests was to determine the durability of concrete cured for nine days before being subjected to freezing and thawing action.

Test results show that dynamic modulus of elasticity of an air-entrained concrete, after reaching its 28 day strength, is reduced by 38 percent at the end of 250 freezing and thawing cycles, air content being 5 ± percent of the concrete volume.

As the use of prestressed concrete construction becomes increasingly widespread it becomes necessary to realize that there are certain physical limitations of concrete which must be recognized and taken into consideration. It is the job of the research engineer to determine these limitations and impose restrictions upon the construction engineer. As an example, it is the custom to apply pre-stress load to the concrete at early ages, yet very little is known about the strength and physical properties of concrete at these early ages. It is the intent of this study to add to the limited fund of knowledge concerning the effects of air-entrainment on the freeze-thaw characteristics at early ages"--Introduction, pages 1-2.

Advisor(s)

Carlton, E. W.

Committee Member(s)

Gevecker, Vernon A. C., 1909-1992
Davidson, Robert F., 1911-1971
Heagler, John B., 1924-1999
Planje, Theodore J., 1919-1980

Department(s)

Civil, Architectural and Environmental Engineering

Degree Name

M.S. in Civil Engineering

Publisher

Missouri School of Mines and Metallurgy

Publication Date

1960

Pagination

v, 52 pages

Note about bibliography

Includes bibliographical references (pages 50-51).

Rights

© 1960 Ugur Ozoguz, All rights reserved.

Document Type

Thesis - Open Access

File Type

text

Language

English

Subject Headings

Concrete -- Curing -- Testing
Air-entrained concrete -- Evaluation
Prestressed concrete -- Testing

Thesis Number

T 1243

Print OCLC #

5928419

Electronic OCLC #

959830728

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