Cellular Concretes Part 1 Composition and Methods of Preparation

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Title: Cellular Concretes Part 1 Composition and Methods of Preparation

Author(s): Rudolph C. Valore, Jr.

Publication: Journal Proceedings

Volume: 50

Issue: 5

Appears on pages(s): 773-796

Keywords: no keywords

Date: 5/1/1954

Abstract:
A review is given of methods of preparation and physical properties of moist-and high-pressure steam-cured cellular concretes, ranging in density from 10 to 100 lb per cu ft, as they have evolved in Europe in the past 30 years. Data are given for Swedish, Danish, Russian, German, British, and Belgian mate-rials, and for experimental mixtures prepared at the National Bureau of Standards. The most economical and controllable cell-forming process, which is preformed foaming, employs hydrolyzed protein foaming agent,s. Aluminum powder and hydrogen peroxide gas-forming processes and the ex-cess water process are also described. Moist-cured materials contain portland cement, neat or with sand; they are used as insulation, roof or floor fills, and for fire prot,ection. Cellular neat cement has adequate strength for structural use at, densities above 40 lb per cu ft but the linear drying shrinkage ranges from 0.3 to 0.6 percent. Cement-sand mixtures have lower strength, higher shrinkage, and higher absorpt,ion than lightweight aggregate concretes of comparable density. Autoclaved materials contain portland cement or lime and finely divided siliceous materials such as ground sand, fly ash, and burned oil shale. Ratios of binder to “pozzolan” range from 1:0.5 to 1:4 for cement and 19 to 1:6 for lime, depending on fineness and composition of the binder and siliceous ma-terial. Compressive strengths were 250 to 1000 psi at 30 lb per cu ft, 400 to 2000 psi at 40 lb per cu ft, and 800 to 3000 psi at 50 lb per cu ft. Flexural strengths were 1/5 to 1/3 of the compressive strength. Drying shrinkages ranged from 0.01 to 0.10 percent. Water absorptions were 20 to 50 percent by volume. Elasticity, thermal expansion, fire resistance, and acoustic properties are also discussed. Thermal conductivity data from various sources are in good agreement and are a function of density from 10 to 70 lb per cu ft, regardless of composi-tion, cell-forming process, or curing.