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Microstructure and Transport Properties of Porous Building Materials. Part 2. Three-Dimensional X-Ray Tomographic Studies.


pdf icon Microstructure and Transport Properties of Porous Building Materials. Part 2. Three-Dimensional X-Ray Tomographic Studies. (992 K)
Bentz, D. P.; Quenard, D. A.; Kunzel, H. M.; Baruchel, J.; Peyrin, F.; Martys, N. S.; Garboczi, E. J.

Materials and Structures, Vol. 33, No. 227, 147-153, April 2000.

Keywords:

building materials; transport properties; porous materials; diffusivity; air permeability; microscopy; digital imaging; computer models; image processing; microstructural characterization; permeability; vapor diffusivity; x ray microtomography

Abstract:

Three-dimensional X-ray microtomography is used to obtain three-dimensional images of the microstructure of two types of brick. The images arc processed to remove the noise (random and circular pattern) and then threshold to match the porosity determined experimentally. The 3-D binary imagcs are then analyzed to estimate their vapor diffusivity and air permeability to compare to experimental data published in part one of this report. Care must be taken in obtaining the tomographic images at a resolution that both enables isolation and quantification of the pores of interest and provides a representative elementary volume for the transport property calculations. In general, the agreement between computed and measured properties is reasonable, suggesting that X-ray microtomography can provide valuable information on the characteristics and properties of the pore networks developed in these porous building materials. A preliminary evaluation indicates that the Katz-Thompson relationship between permeability, diffusivity, and pore size is valid for these materials.