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Document Type

Thesis - University Access Only

Award Date

1989

Degree Name

Master of Science (MS)

Department / School

Civil Engineering

First Advisor

M. N. Hassoun

Abstract

Cellular concrete is one type of lightweight concrete. It consists of a system of macroscopic air cells uniformly distributed in either a matrix of cement or of aggregate and cement paste. The cell size varies approximately from 0.004 to 0.04 in. (0.1 to 1.0 mm). The skin of the air cells must be tough in order to withstand the rigor of mixing and placing, during which periods the cells are separated, coated with cement paste, and the concrete is pumped or transported to the casting· position. In this discussion it is assumed that the air cells are performed as foam and added to the mix. But it is also. possible to form the air cells in the slurry by chemical reaction or by vigorous mixing- of the slurry with a proper foam concentrate in a high-speed mixer. In reference to the density of cellular concrete, confusion can be avoided by always stating the moisture condition of the mix along with the density. The significant moisture conditions are wet density (density of fresh concrete), air dry density (at stated age and curing condition), and oven-dry density which is. usually only used for determination of thermal conductivity. The change in density due to air drying is a function of temperature, humidity, duration of the drying period, the wet density of concrete, the water-cement ratio, and the surface area ratio of the element. The relation of air density to wet density would, therefore, seem to be a complicated one. However, for cellular concrete of wet density 40 to 120 pcf (640 to 1920 kg/m3), the air-dry density of 5 pcf (80 kg/m3) is less than the wet density. There is no upper or lower limit of the wet density of cellular concrete mixes. The approximate wet density range is considered to be from 20 to 120 pcf (320 to 1920 kg/m3).

Library of Congress Subject Headings

Concrete beams

Lightweight concrete

Format

application/pdf

Number of Pages

256

Publisher

South Dakota State University

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