Masters Theses

Abstract

"Air entrained concrete over the past eighteen years has received national recognition as a result of its satisfactory performance in highway concrete pavements and other concrete structures subjected to outside exposure.

Numerous highway departments over the entire United States have laid test slabs made of air entrained concrete. Among those to date are Pennsylvania, New Jersey, New York, Connecticut, Massachusetts, Vermont, Maine, Illinois, Missouri and California. The primary purpose in building these test slabs was to investigate their durability or resistance to freezing and thawing and the action of various salts on air entrained concrete. The results of the test slabs were excellent. It was also found that air entrainment increased the workability, reduced bleeding and water-gain after placing and lessened the segregation.

The use of air entrainment of concrete is not limited to highway slabs. It is used in airport runways, in concrete structures such as building dams, bridges, etc. and by ready-mix plants in almost all of their projects. The Corp of Engineers uses air entrained concrete in all exposed structures that will be subjected to extreme weather conditions, salt-water action or de-icing chemicals.

In the near future the Missouri Highway Commission contemplates the building of prestressed highway slabs. A most important factor to be resolved is the effect of air entrained concrete on the strength of prestressed concrete highway slabs. Very little literature is to be found on air entrained concrete at the early ages of 6 hours to 72 hours. In order to design concrete slabs for prestressing, it would be most desirable to know at what early age the slabs could be prestressed advantageously. This knowledge of the strength of concrete at early ages will enable the engineers to prestress the slabs, and would minimize the interruption or delay that will be necessary due to the prestressing operations during the construction of the new highway. This will mean a saving of time and money to the taxpayer….

The results indicated that the concrete strength decreased uniformly with the increase in air content. With a constant Water-Cement ratio by weight, the decrease in strength amounted to 195 psi (about 5 percent average) for each percent of air entrained. Also, where the Water-Cement ratio is held constant, the test show about the same reduction in strength for each percent of air entrained for the higher Water-Cement ratio cf .65 as for the lower constant Water- Cement ratio of .45* It was also found from the average curve of all tests, that with the same Water-Cement ratio being maintained, a loss of approximately 105,000 psi static modulus of elasticity for each percent of air entrained can be expected for average concrete mixes"--Introduction, pages 1-2, 4.

Advisor(s)

Carlton, E. W.

Department(s)

Civil, Architectural and Environmental Engineering

Degree Name

M.S. in Civil Engineering

Publisher

Missouri School of Mines and Metallurgy

Publication Date

1956

Pagination

iv, 89 pages

Note about bibliography

Includes bibliographical references (pages 87-88).

Rights

© 1956 James Arthur Spilman, All rights reserved.

Document Type

Thesis - Open Access

File Type

text

Language

English

Subject Headings

Air-entrained concrete -- TestingPavements, Concrete -- TestingStrength of materials -- Testing

Thesis Number

T 1132

Print OCLC #

5153455

Electronic OCLC #

951817666

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