A Vacuum Method of Measuring the Air Content of Fresh Concrete

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Title: A Vacuum Method of Measuring the Air Content of Fresh Concrete

Author(s): George L. Pigman

Publication: Journal Proceedings

Volume: 38

Issue:

Appears on pages(s): 121-132

Keywords:

Date: 11/1/1941

Abstract:
A method of measuring the air content of freshly mixed concrete has been developed, in which the air is removed at the reduced absolute pressure of ap-proximately 17 mm of mercury. Determination of the air content is made entirely by volume measurements and does not require any information on the specific gravity of the components of the concrete. The reproducibility of results was satisfactory and varied with the wetness of the mix, being better for the wetter concretes with a flow of 85 to I IO than for concrete with a flow of 55. The air content was increased by use of a finer sand, but was reduced by increasing the cement content of the mix. It was found that concretes normally containing less than I percent of air had the air contents increased to values ranging from 1.5 to I4 percent by the addition of 0.05 percent of various aerating agents.