SEDL / STP / STP1064-EB / STP23472S

An Investigation of the Formation of Carboaluminates

Klemm, WA
Manager and assistant manager, Central Process Laboratory, Southwestern Portland Cement Co., Victorville, CA

Adams, LD
Manager and assistant manager, Central Process Laboratory, Southwestern Portland Cement Co., Victorville, CA

Pages: 13    Published: Jan 1990

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Abstract

The formation of carboaluminates in hydrated cement paste is often regarded as analogous to the formation of ettringite. This paper presents a review of the literature and X-ray diffraction data which indicate that the reaction of calcium carbonate with Type II Portland cement and the resulting formation of carboaluminates is much slower than the reaction of calcium sulfate and the resulting formation of ettringite.

The use of solubility products of the possible aluminate-ferrite-monosubstituted (AFm) and aluminate-ferrite-trisubstituted (AFt) phases is suggested for prediction of the stable equilibrium phases and reaction sequences during hydration of cements with carbonate additions.