Effect of silica particle size on the formation of calcium silicate hydrate [C-S-H] using thermal analysis

Maddalena, Riccardo and Hall, Christopher and Hamilton, Andrea (2019) Effect of silica particle size on the formation of calcium silicate hydrate [C-S-H] using thermal analysis. Thermochimica acta, 672. pp. 142-149. ISSN 0040-6031 (https://doi.org/10.1016/j.tca.2018.09.003)

[thumbnail of Maddalena-etal-TA-2018-Effect-of-silica-particle-size-on-the-formation-of-calcium-silicate-hydrate]
Preview
 Text. Filename: Maddalena_etal_TA_2018_Effect_of_silica_particle_size_on_the_formation_of_calcium_silicate_hydrate.pdf
Final Published Version
License: Creative Commons Attribution 4.0 logo
Download (1MB)| Preview

Abstract

Calcium silicate hydrate (C-S-H) is made by mixing calcium hydroxide (portlandite), silica and water at two calcium oxide to silica (C/S) ratios, using nano-silica and silica fume. We investigate how silica particle size influences the rate and extent of formation of C-S-H at room temperature by isothermal calorimetry, thermal analysis, Raman spectroscopy and X-ray diffraction. Rate of reaction increases as silica particle size decreases, and is five times greater with nano-silica than with silica fume. Final composition depends only on initial C/S ratio. Compositions at 28 days are estimated from thermogravimetric and X-ray diffraction data. There is a weak maximum in the reaction rate of nanosilica pastes about 20–30 h after mixing. The overall kinetics is well described by a simple exponential (first-order) reaction model. The early-time reaction rate around the rate maximum is described by an Avrami model.

ORCID iDs

Maddalena, Riccardo ORCID logoORCID: https://orcid.org/0000-0001-6251-3782, Hall, Christopher and Hamilton, Andrea ORCID logoORCID: https://orcid.org/0000-0002-3124-3182;
CORE (COnnecting REpositories)