Void Space as a Basis for Producing Air-Entrained Concrete


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Title: Void Space as a Basis for Producing Air-Entrained Concrete

Author(s): T. C. Powers

Publication: Journal Proceedings

Volume: 50

Issue: 5

Appears on pages(s): 741-760

Keywords: no keywords

Date: 5/1/1954

Basic studies show that the function of entrained air is to protect the paste and that the effectiveness depends on the distance from void to void in the paste. Freezing and thawing tests show different mixes have nearly equal frost resistance when the spacing factor is about 0.01 in. The amount of air iequired for a given spacing factor is directly proportional to the paste content and is greater the smaller the specific surface of the air voids. The void system is made up of relatively coarse natural voids and entrained bubbles. Characteristics of natural voids vary with aggregate grading, consistency, and other mix characteristics. With a given amount of air-entraining agent in the mixing water, the amount of entrained bubbles is smaller the greater the quantity of cement or other fine solids in the water. A procedure is suggested for designing n fixed spacing factor where such procedure is economically feasible.