Relationships between Composition and Density of Tobermorite, Jennite, and Nanoscale CaO-SiO2-H2O

Published

May 16, 2010

Author(s)

Andrew J. Allen, Jeffrey Thomas, Hamlin M. Jennings

Abstract

Relationships between composition, mass density, and atomic packing density for CaO{SiO2{H2O (C{S{H) gel, the main hydration product of ce- ment, and its mineral analogues tobermorite and jennite, are examined. A phase diagram approach is proposed, in which published values for mass density and composition of these phases are converted into continuous phase lines by assuming a xed value for the density of physically bound water contained in the interlayer space. Di erences in the atomic packing density of these phases are then explored by calculating the e ective mass density of CaO or CaO H2O required to transition from one phase line to another. These calculations indicate that tobermorite and jennite have similar atomic packing densities, while that of C{S{H gel is considerably higher. The rel- atively high density of C{S{H gel can be attributed to both its defective atomic structure and to its nanoparticulate morphology. New experimental measurements for the composition and mass density of C{S{H gel in cement paste cured at elevated temperatures, dried and resaturated, and hydrated with silica fume are presented.

Citation

Journal of Physical Chemistry C

Volume

114

Pub Type

Journals

Keywords

calcium-silicate hydrate gel, tobermorite, jennite, density, composition, microstructure characterization

Citation

Allen, A. , Thomas, J. and Jennings, H. (2010), Relationships between Composition and Density of Tobermorite, Jennite, and Nanoscale CaO-SiO2-H2O, Journal of Physical Chemistry C (Accessed December 26, 2024)