Microstructure and Transport Properties of Porous Building Materials. Part 2. Three-Dimensional X-Ray Tomographic Studies.
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.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899