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Composition and Density of Amorphous Calcium-Silicate-Hydrate in Cement



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


Despite intensive research for over a century, the main binding reaction product of cement hydration, calcium-silicate-hydrate (C-S-H) gel, is not fully understood. By combining absolute-calibrated small-angle and ultrasmall-angle neutron and x-ray scattering data, and by exploiting the neutron isotope effect between hydrogen and deuterium in both water and methanol contrast variation studies, we have determined the mean formula and density for the amorphous solid phase of C-S-H gel in hydrated cement. Also, the nanoscale calcium hydroxide phase that coexists with C-S-H gel has been quantified. The formula and density for solid C-S-H differ from published values for C-S-H, saturated or dried under various conditions. This has implications for how water is associated with C-S-H, how solid C-S-H gel should be defined, and how the chemically active (C-S-H) cement surface area should be quantified.
Nature Materials


C-S-H gel, cement, microstructure characterization, nanoscale structure, small-angle scattering


Allen, A. , Thomas, J. and Jennings, H. (2007), Composition and Density of Amorphous Calcium-Silicate-Hydrate in Cement, Nature Materials, [online], (Accessed June 20, 2024)


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Created January 16, 2007, Updated February 19, 2017