Dissolution of Portlandite in Pure Water: Part 1 Molecular Dynamics (MD) Approach |
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| Authors: | Khondakar Mohammad Salah Uddin Mohammadreza Izadifar Neven Ukrainczyk Eduardus Koenders Bernhard Middendorf |
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| Institution: | 1.Department of Structural Materials and Construction Chemistry, University of Kassel, Mönchebergstraße 7, 34125 Kassel, Germany;2.Institute of Construction and Building Materials, Technical University of Darmstadt, Franziska-Braun-Str. 3, 64287 Darmstadt, Germany; (M.I.); (E.K.) |
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| Abstract: | The current contribution proposes a multi-scale bridging modeling approach for the dissolution of crystals to connect the atomistic scale to the (sub-) micro-scale. This is demonstrated in the example of dissolution of portlandite, as a relatively simple benchmarking example for cementitious materials. Moreover, dissolution kinetics is also important for other industrial processes, e.g., acid gas absorption and pH control. In this work, the biased molecular dynamics (metadynamics) coupled with reactive force field is employed to calculate the reaction path as a free energy surface of calcium dissolution at 298 K in water from the different crystal facets of portlandite. It is also explained why the reactivity of the (010), (100), and (10) crystal facet is higher compared to the (001) facet. In addition, the influence of neighboring Ca crystal sites arrangements on the atomistic dissolution rates is explained as necessary scenarios for the upscaling. The calculated rate constants of all atomistic reaction scenarios provided an input catalog ready to be used in an upscaling kinetic Monte Carlo (KMC) approach. |
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| Keywords: | cement hydration dissolution of portlandite free energy surfaces surface properties molecular dynamics simulation reactive force field metadynamics |
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