open access

https://hdl.handle.net/2115/89294

Electrostatic properties of C-S-H and C-A-S-H for predicting calcium and chloride adsorption

英語

Surface complexation model

2021-08

Elsevier

Cement & concrete composites

121

104109

The adsorption capacity of cement hydrates considerably affects the ionic ingress into cementitious materials. In this study, the surface electrostatic properties of calcium silicate hydrate (C-S-H) and calcium aluminosilicate hydrate (C-A-S-H) were determined to understand the effects of the properties on calcium and chloride adsorption. The density of the surface functional groups was determined by analysing the structure of C-S-H and CASH through Al-27 and Si-29 MAS NMR. The surface sites of SiOH and AlOH are available in CASH whereas C-S-H has SiOH groups for ionic adsorption. We found that the incorporation of aluminium decreases the number of total adsorption sites in C-A-S-H. Furthermore, the site density increased with Ca/(Si + Al). To understand the C-A-S-H/solution interface, a triple-layer surface complexation model was developed and the associated equilibrium constants for depmtonation, calcium, and chloride adsorption were determined by fitting the experimental data of potentiometric titration and zeta potential measurement results. The estimated surface complexation modelling parameters were verified by predicting the experimental data of calcium and chloride adsorption on C-S-H and C-A-S-H.

学術雑誌論文

Accepted Manuscript

Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International

© <2021>. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/

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