Hydration of tricalcium silicate in the presence of synthetic calcium–silicate–hydrate

Abstract

Hydration of tricalcium silicate in the presence of synthetic calciumsilicate-hydrate Alizadeh, Rouhollah; Raki, Laila; Makar, Jon M.; Beaudoin, James J.; Moudrakovski, Igor http://www.nrc-cnrc.gc.ca/irc H ydra t ion of t ric a lc ium silic a t e in t he pre se nc e of synt he t ic c a lc iumsilic a t e -hydra t e NRCC-51324Alizadeh, R.; Raki, L.; Makar, J.M.; Beaudoin, J.J.; Moudrakovski, I. September 2009A version of this document is published in / Une version de ce document se trouve dans:Journal of Materials Chemistry, v. 19, no. 33, September 9, 2009, pp. 1-19, DOI: 10.1039 /B910216GThe material in this document is covered by the provisions of the Copyright Act, by Canadian laws, policies, regulations and international agreements. Such provisions serve to identify the information source and, in specific instances, to prohibit reproduction of materials without written permission. For more information visit http://laws.justice.gc.ca/en/showtdm/cs/C-42Les renseignements dans ce document sont protégés par la Loi sur le droit d'auteur, par les lois, les politiques et les règlements du Canada et des accords internationaux. Ces dispositions permettent d'identifier la source de l'information et, dans certains cas, d'interdire la copie de documents sans permission écrite. Pour obtenir de plus amples renseignements : http://lois.justice.gc.ca/fr/showtdm/cs/C-42 AbstractThe early age hydration of tricalcium silicate, the main chemical compound in Portland cement, was studied in the presence of synthetic calcium silicate hydrate (C-S-H) addition having C/S ratios=0.8 and 1.2. Isothermal conduction calorimetry, scanning electron microscopy, differential scanning calorimetry and 29 Si MAS NMR were employed in order to investigate events occurring during various stages of the hydration. The results that were analyzed using novel methods in cement chemistry showed that the addition of seeds of synthetic C-S-H significantly accelerated the hydration of C 3 S. The extent of the acceleration was dependant on the amount and chemical composition of the C-S-H seeds. It was suggested that the synthetic C-S-H significantly increased the rate and degree of dissolution of the C 3 S particles.It was also found that the nucleation and silicate polymerization of the C-S-H that formed during the hydration of the C 3 S phase was promoted. Direct evidence of the seeding effect was provided. The properties of the resulting C-S-H hydration products seemed to be dependant on the lime to silica ratio of the synthetic C-S-H. It was suggested that the silicate polymerization and chemical composition of the hydration products of silicate phases may be manipulated through C-S-H seeding. As the chemical and mechanicalproperties of C-S-H are largely controlled by its C/S ratio, this method should provide a unique tool for tailoring the nanostructure of the hydration products of Portland cement through the addition of selective C-S-H seeds for optimum engineering and durability performance.Keywords: Tricalcium Silicate (C 3 S), Calcium Silicate Hy...

Discussion of “Dissolution theory applied to the induction period in alite hydration”

“…A direct comparison between the image presented by Juillard et al [1] in their Figure 7 and the images in Makar, Esseghaier and Chan [2] is difficult to make due to potential differences in the C 3 S material used in each case. However, the results with and without synthetic C S H in Alizadeh, et al [7] are directly comparable to each other and it is apparent that a much higher degree of pitting was present in the samples with synthetic C S H throughout the hydration process. This would also argue against dislocation driven dissolution, as increased dissolution activity under that mechanism should be expected to primarily produce deeper pits, not a higher number of surface pits.…”

“…There are two special cases where the pits do appear to form before the onset of the main hydration reactions: where alite is exposed to excessive water as in Juilland et al's[1] Figure 7 and earlier work by Ménétrier, et al [6], and in the presence of synthetic C S Hs (Figure 1), which have extremely high surface areas [7]. The early formation of pits in the former cases suggests that ion concentration in the mix water does indeed limit the dissolution of alite surfaces, but in the latter case the effect is likely due to initial reactions on the high surface area synthetic C S H itself during the first few minutes of exposure to water.…”

Calorimetric study of the early stages of the nanosilica - tricalcium silicate hydration. Effect of temperature

“…Calorimetric readings were taken at three curing temperatures (25,40 and 65 °C) with a Thermometric TAM Air analyser fitted with eight calorimetric channels having twin chambers, with each channel able to operate separately. The sample was placed in one of the chambers and water (used as a reference in accordance with the literature (9, 10)) in sufficient amounts to have the same heat capacity as the paste studied in the other.…”

Nano-optimized Construction Materials by Nano-seeding and Crystallization Control

“…Many scientists have already attempted to enhance the mechanical properties by seeding concrete [Duriez, 1956]. Despite the fact that literature is rich in interesting articles related to this topic [Alizadeh, 2009;Thomas, 2009], not a single product based on a seeding material has come to the market.…”