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Application of Digital-Image-Based Models to Microstructure, Transport Properties, and Degradation of Cement-Based Materials.


pdf icon Application of Digital-Image-Based Models to Microstructure, Transport Properties, and Degradation of Cement-Based Materials. (1228 K)
Bentz, D. P.; Garboczi, E. J.; Martys, N. S.

Modelling of Microstructure and Its Potential for Studying Transport Properties and Durability. 1996, Kluwer Academic Publishers, Jennings, H., Editor(s), 167-185 pp, 1996.

Keywords:

building technology; cements; cement based materials; computer models; microstructure; transport properties; degradation

Abstract:

As multi-phase composites, cement-based materials have physical properties that are strongly influenced by the volume fractions and topologies of the individual phases. Because of their inherent random nature, these materials often defy a simple geometrical description. The use of digital-image-based models allows one to realistically represent this class of materials, as resultant microstructures can be quickly quantified with respect to the volume fraction and interconnectivity or percolation of each phase or any combination of phases. In addition, physical properties such as diffusivity and permeability can be conveniently computed using finite-difference or finite-element techniques. These computer modeling techniques will be demonstrated for microstructural models of these materials at two scales: hydrated cement paste at the micrometer level and calcium silicate hydrate gel at the nanometer level. The properties computed for the gel at the nanometer level can be used as input for the micrometer-level model. Examples of the importance of volume fraction and phase topology in determining physical properties will be presented for each of the four major phases of cement paste: anhydrous cement, capillary porosity, calcium silicate hydrate gel, and calcium hydroxide. Results of the models are compared to existing experimental data, and good agreement is observed. These techniques are seen as one critical link in developing sound scientific relationships between the microstructure and the transport properties and durability of cement-based materials.