A reaction-diffusion model for simulating 3-D microstructure development of cement paste

Title: A reaction-diffusion model for simulating 3-D microstructure development of cement paste
Author(s): J.W. Bullard
Paper category : conference
Book title: International RILEM Symposium on Concrete Modelling - ConMod '08
Editor(s): E. Schlangen and G. De Schutter
Print-ISBN: 978-2-35158-060-8
e-ISBN: 978-2-35158-076-9
Publisher: RILEM Publications SARL
Publication year: 2008
Pages: 377 - 384
Total Pages: 8
Nb references: 18
Language: English

Abstract: The early-age hydration of cement paste is governed by a number of coupled chemical reactions, all of which are mediated by dissolved species in the pore solution. To capture the fundamental kinetic aspects of hydration, a model is required that can accurately simulate the rate processes of electrolyte diffusion, dissociation, nucleation, and crystal growth.
Moreover, such a model needs to be directly linked to the three-dimensional (3-D) microstructure development of the paste. If properly formulated, a suitable model should be able to simulate any one of a number of plausible hydration mechanisms, by which comparison to experimental data can be used to gain insight into the actual chemical kinetics.
Such information can aid in development of tailored chemical admixtures for controlling the progress of hydration. This paper will describe a new 3-D reaction-transport model, called HydratiCA, that has been formulated for just such purposes. The model is based on cellular automaton algorithms for diffusion and chemical reactions that may be shown to converge numerically to the generalized diffusion equation for nonideal solutions and the standard rate equations for coupled elementary reactions, respectively. Examples will be shown of how the model can be used to assess the plausibility of alternate hypotheses for the onset of the acceleration stage of hydration of tricalcium silicate and for the early-age hydration kinetics of tricalcium aluminate/calcium sulfate pastes.

Online publication: 2009-06-15
Publication type : full_text
Public price (Euros): 0.00

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