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Effect of silica particle size on the formation of calcium silicate hydrate using thermal analysis

Maddalena, Riccardo 2019. Effect of silica particle size on the formation of calcium silicate hydrate using thermal analysis. Thermochimica Acta 672 , pp. 142-149. 10.1016/j.tca.2018.09.003

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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 nanosilica 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 nanosilica 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 are 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.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Engineering
Publisher: Elsevier
ISSN: 0040-6031
Date of First Compliant Deposit: 28 November 2018
Date of Acceptance: 2 September 2018
Last Modified: 26 Feb 2019 15:24
URI: http://orca.cf.ac.uk/id/eprint/117167

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