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Dissolution of Portlandite in Pure Water: Part 2 Atomistic Kinetic Monte Carlo (KMC) Approach

Izadifar, Mohammadreza ; Ukrainczyk, Neven ; Salah Uddin, Khondakar Mohammad ; Middendorf, Bernhard ; Koenders, Eduardus (2022):
Dissolution of Portlandite in Pure Water: Part 2 Atomistic Kinetic Monte Carlo (KMC) Approach. (Publisher's Version)
In: Materials, 15 (4), MDPI, e-ISSN 1996-1944,
DOI: 10.26083/tuprints-00021020,
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Item Type: Article
Origin: Secondary publication DeepGreen
Status: Publisher's Version
Title: Dissolution of Portlandite in Pure Water: Part 2 Atomistic Kinetic Monte Carlo (KMC) Approach
Language: English
Abstract:

Portlandite, as a most soluble cement hydration reaction product, affects mechanical and durability properties of cementitious materials. In the present work, an atomistic kinetic Monte Carlo (KMC) upscaling approach is implemented in MATLAB code in order to investigate the dissolution time and morphology changes of a hexagonal platelet portlandite crystal. First, the atomistic rate constants of individual Ca dissolution events are computed by a transition state theory equation based on inputs of the computed activation energies (ΔG*) obtained through the metadynamics computational method (Part 1 of paper). Four different facets (100 or 1¯00 , 010 or 01¯0, 1¯10 or 11¯0, and 001 or 001¯) are considered, resulting in a total of 16 different atomistic event scenarios. Results of the upscaled KMC simulations demonstrate that dissolution process initially takes place from edges, sides, and facets of 010 or 01¯0 of the crystal morphology. The steady-state dissolution rate for the most reactive facets (010 or 01¯0) was computed to be 1.0443 mol/(s cm²); however, 0.0032 mol/(s cm²) for 1¯10 or 11¯0, 2.672 × 10⁻⁷ mol/(s cm²) for 001 or 001¯, and 0.31 × 10⁻¹⁶ mol/(s cm²) for 100 or 1¯00 were represented in a decreasing order for less reactive facets. Obtained upscaled dissolution rates between each facet resulted in a huge (16 orders of magnitude) difference, reflecting the importance of crystallographic orientation of the exposed facets.

Journal or Publication Title: Materials
Volume of the journal: 15
Issue Number: 4
Publisher: MDPI
Collation: 17 Seiten
Uncontrolled Keywords: portlandite, calcium hydroxide, atomistic kinetic Monte Carlo, upscaling approach, dissolution rate
Classification DDC: 500 Naturwissenschaften und Mathematik > 540 Chemie
600 Technik, Medizin, angewandte Wissenschaften > 620 Ingenieurwissenschaften
Divisions: 13 Department of Civil and Environmental Engineering Sciences > Institute of Construction and Building Materials
Date Deposited: 11 Apr 2022 11:19
Last Modified: 11 Apr 2022 11:20
DOI: 10.26083/tuprints-00021020
Corresponding Links:
URN: urn:nbn:de:tuda-tuprints-210206
Additional Information:

Part 1: urn:nbn:de:tuda-tuprints-210215

SWORD Depositor: Deep Green
URI: https://tuprints.ulb.tu-darmstadt.de/id/eprint/21020
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