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



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


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.
Journal of Physical Chemistry C


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


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 April 21, 2024)
Created May 16, 2010, Updated February 19, 2017