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Hard Core/Soft Shell Microstructural Model for Studying Percolation and Transport in Three-Dimensional Composite Media.

pdf icon Hard Core/Soft Shell Microstructural Model for Studying Percolation and Transport in Three-Dimensional Composite Media. (4175 K)
Bentz, D. P.; Garboczi, E. J.; Snyder, K. A.

NISTIR 6265; 55 p. January 1999.

Available from:

National Technical Information Service (NTIS), Technology Administration, U.S. Department of Commerce, Springfield, VA 22161.
Telephone: 1-800-553-6847 or 703-605-6000;
Fax: 703-605-6900.
Order number: PB99-114647


building technology; computer models; concretes; diffusivity; microstructure; percolation; simulation


This user's manual provides documentation and computer program listings for the three-dimensional hard core/soft shell microstructure model developed at the National Institute of Standards and Technology. The model has been developed to represent the three phase microstructure of a concrete composite consisting of a bulk matrix (cement paste), hard core particles located at random in the bulk (aggregates), and a concentric soft shell surrounding each hard core particle (interfacial transition zone paste). However, this microstructural model is generic in nature and has also been applied to modelling air voids in concrete, macro-defect-free cements, and silica sol gels. Any system consisting of partially overlapping or totally non-overlapping spherical particles can be modelled using the developed computer programs, perhaps with some minor modifications. In addition to generating a representative 3-D microstructure, the programs can also be used to assess the percolation characteristics of the microstructure and estimate a diffusivity (or electrical or thermal conductivity) for the composite media. Complete program listings and example datafiles are provided in the appendices of this documentation and the software is also available for downloading via anonymous ftp. The computer codes are available via anonymous ftp as part of the Computer Integrated Knowledge System for High-Performance Concrete being developed as part of the Partnership for High Performance Concrete Technology program in the Building and Fire Research Laboratory at the NIST. They may be accessed in the /ftp/pub/HCSSMODEL sub-directory from ( by loggin in as user "anonymous" and providing your e-mail address as the password. Postscript and pdf versions of this manual are also available in a subdirectors, /ftp/pub/HCSSMODEL/manual.