Preprint Article Version 2 This version is not peer-reviewed

Water Adsorption on the β-Dicalcium Silicate Surface from DFT Simulations

Version 1 : Received: 5 April 2018 / Approved: 6 April 2018 / Online: 6 April 2018 (15:24:22 CEST)
Version 2 : Received: 1 August 2018 / Approved: 2 August 2018 / Online: 2 August 2018 (08:46:23 CEST)

How to cite: Wang, Q.; Manzano, H.; López-Arbeloa, I.; Shen, X. Water Adsorption on the β-Dicalcium Silicate Surface from DFT Simulations. Preprints 2018, 2018040080 (doi: 10.20944/preprints201804.0080.v2). Wang, Q.; Manzano, H.; López-Arbeloa, I.; Shen, X. Water Adsorption on the β-Dicalcium Silicate Surface from DFT Simulations. Preprints 2018, 2018040080 (doi: 10.20944/preprints201804.0080.v2).

Abstract

β-dicalcium silicate (β-Ca2SiO4, or β-C2S in cement chemistry notation) is one of the most important minerals in cement. An improvement of its hydration rate would be the key point for developing environmentally friendly cements with lower energy consumption and CO2 emissions. However, there is a lack of fundamental understanding on the water/β-C2S surface interactions. In this work we aim to evaluate the water adsorption on three β-C2S surfaces at the atomic scale using density functional theory (DFT) calculations. Our results indicate that thermodynamically favorable water adsorption takes place in several surface sites, with a broad range of adsorption energies (−0.78 to −1.48 eV), depending on the particular mineral surface and adsorption site. To clarify the key factor governing the adsorption, the electronic properties of water at the surface were analyzed. The partial density of states (DOS), charge analysis, and electron density difference analyses suggest a dual interaction of water with β-C2S (100) surface: a nucleophilic interaction of the water oxygen lone pair with surface calcium atoms, and an electrophilic interaction (hydrogen bond) of one water hydrogen with surface oxygen atoms. Despite the elucidation of the adsorption mechanism, no correlation was found between the electronic structure and the adsorption energies.

Subject Areas

Belite; hydration; Density Functional Theory; water adsorption; calcium silicate

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