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Interpretation of Compositional Patterns Found by Quantitative Energy Dispersive X‐ray Analysis for Cement Paste Constituents.
Author(s) -
Bonen David,
Diamond Sidney
Publication year - 1994
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1994.tb07065.x
Subject(s) - ettringite , mineralogy , calcium hydroxide , homogeneous , materials science , hydroxide , cement , gypsum , portland cement , ferrite (magnet) , analytical chemistry (journal) , chemistry , chemical engineering , composite material , inorganic chemistry , thermodynamics , chromatography , physics , engineering
More than 200 individual particles within a portland scement paste were morphologically categorized by backscatter SEM and analyzed systematically by EDXA. Nearly all of the analyses fall either in a dense cluster around a mean C‐S‐H gel composition or along tie lines connecting this composition to theoretical compositions for calcium hydroxide, monosulfate, ettringite, and ferrite. “Phenograin” C‐S‐H gel (formed as a direct replacement product within large cement grains) contains small amounts of Al, Fe, and S, but otherwise shows almost negligible compositional variation. In contrast, smaller groundmass particles and shells of gapped phenograins show a slightly differentc S‐H gel composition. Some of these, despite being morphologically homogeneous, show compositions falling along tie lines to the other recognized phases. This is attributed to extensive occurrence of intimate mixtures of C‐S‐H gel with the other components below the scale of SEM observation. Ionic substitutions appear to be minor except for the monosulfate and ettringite components in such mixtures. These show a variable but usually high deficiency in the sulfate content.