Studies on the Cementious Phases of Autoclaved Concrete Products Made of Different Raw Materials


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Title: Studies on the Cementious Phases of Autoclaved Concrete Products Made of Different Raw Materials

Author(s): George L. Kalousek

Publication: Journal Proceedings

Volume: 50

Issue: 1

Appears on pages(s): 365-378

Keywords: no keywords

Date: 1/1/1954

Physical tests on sand and gravel units made with different constant-weight mixtures of lime and cement in fixed proportions to the aggregate indicated that strength was directly proportional to unit weight of the raw block. At any given density, strength was largely independent of the cement to lime ratio. Cement generally increased the densities more than did the lime and, therefore, generally showed better strengths. Drying shrinkage appeared to be independent of the lime-cement proportions in sand and gravel units. In chemical tests using aggregate fines, compositions of autoclaved lime-cement-silica (quartz) solids ranged in composition from about 0.9 to 1.3 mols of Co0 per mol of SiOz (C/S ratio) providing that silica was present in a suf-ficient amount. Solids made from mixtures deficient in silica contained, in addition to the 1.3 C/S hydrate of the 0.9-1.3 C/S series, a poorly crystallized form of alpha-type dicalcium silicates hydrate. Reaction solids made with pumice and shale also approached low-lime compositions of about 1.0 C/S. Structure-wise these products are closely related to 0.9 to 1.3 C/S series made with silica fines, but extended in composition to values as high as about 1.5 C/S. These, and the phases which extended in composition above a 2.0 C/S ratio, did not undergo any apparent recrystallization to the alpha-type hydrate. Differential thermal analysis, in conjunction with chemical analyses, made it possible to differentiate between solids phases of different C/S ratios made of a given aggregate, or products of a given C/S ratio (from about 0.9 to about 1.3) made with different aggregates.