1854
4940.046
Short, A. and W. Kinniburgh
Structural Engineer
Paper
Institution of Structural Engineers (London, England)
1961
January
16 + app., ref.
Y
Aerated concrete is one of a group of materials described collectively as “lightweight concrete.” The term “lightweight concrete” is somewhat arbitrary; in the past, it has been customary to consider as “lightweight” any concrete of dry density not exceeding 100 lb/cu ft, but the use of reinforced units has led to concretes with a density of 110-115 or even 120 lb/cu ft.The usual method of making concrete light is that of introducing air into its composition, but there are three ways by which this can be done.
1. By using a single-size aggregate, leaving interstitial air-voids; this so-called “no-fines” concrete has a density much lower than an “all-in” aggregate concrete made from the same materials;
2. By employing a porous aggregate, thereby retaining some air within the aggregate itself;
3. By introducing air or other gas into a cement slurry in such a manner that when the cement has set, a uniform cellular product is formed. This last we call “aerated concrete”, although outside the United Kingdom, the terms “gas concrete”, “pore concrete,” “Cellular concrete” and “foamed concrete” are in common use.
By suitable adjustment of its composition and mode of manufacture, a range of aerated concretes can be produced having densities between 25 lb and 90 lb/cu ft, with a correspondingly wide range of other properties.
Aerated concrete has been described as a cement paste into which gas bubbles have been introduced, but in practice, aerated concrete always contains a considerable proportion of siliceous materials in the form of silica flour, ground blast furnace slag, pulverized fuel ash or ground burnt shale. These materials function partly as a filler and partly as a chemical reactant with the binder, which may be Portland cement or lime.