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Next: Introduction
E.J. Garboczi and D.P. Bentz
National Institute of Standards and Technology
Building Materials Division, 226/B348
Gaithersburg, Maryland 20899
A digital-image-based model of the microstructure of cement
paste, coupled with exact transport algorithms, are used to study
the diffusivity of portland cement paste. The principal
variables considered are water:cement ratio, degree of cement
hydration, and capillary porosity. Computational methods are
described, and diffusivity results are presented, which are found
to agree within experimental error with the available
experimental measurements. Model cement pastes prepared with
different water:cement ratios, and having different degrees of
hydration, are found to have diffusivities that lie on a single
master curve when plotted as a function of capillary porosity.
Concepts from percolation theory are used to quantitatively
explain the dependence of diffusivity on capillary porosity. The
effect of silica fume addition on diffusivity is also examined.
1. Introduction
2. Digital-Image-Based Microstructural Model
3. Percolation Properties of the Pore Space
4. Computational Methods
5. Diffusivity Results
6. Cement Paste Diffusivity Dependence on Pore Structure
7. Summary
References