A revised package of computer programs for simulating cement hydration and cement paste microstructure development in three dimensions has been developed. A three-dimensional representation of microstructure is necessary for the computation of percolation and physical properties for comparison to experiment. While previous publications have focused on the validation of the computer model [1] and various extensions [2,3], the purpose of this report is to provide a detailed documentation of the latest version of the computer codes so that other researchers may employ them in studying problems specific to their own interests. It is strongly suggested that potential users of these models also obtain copies of references [1,2,3] and the original user's manual [4] to obtain a better understanding of the technical basis underlying the computer programs documented herein. A NISTIR and a Ph. D. thesis dealing specifically with the incorporation of fly ash into the NIST 3-D cement hydration model are also available [5,6]. The recent use of the model for simulating the microstructure and durability of high-performance cement matrices is described in another Ph. D. thesis [7].
The steps required for going from a two-dimensional image to a simulation of
three-dimensional microstructure development, along with the corresponding
computer program names, are provided in Table 1. The
first two of these steps can now be replaced by accessing the cement images
database available over the internet at
http://ciks.cbt.nist.gov/bentz/phpct/database/images. All of these
programs will be described in detail in sections 2 through 5 of this user's
manual. The computer codes are available via anonymous ftp as part of the
Computer Integrated Knowledge System for High-Performance Concrete (HYPERCON)
[8] being developed in the Building and Fire
Research Laboratory at the National Institute of Standards and Technology.
They may be accessed in the
pub/bfrl/bentz/CEMHYD3D/version20 subdirectory from ftp.nist.gov
(129.6.13.25), by logging in as user "anonymous" and providing your
e-mail address as the password. A postscript version of this manual
is also available at ftp.nist.gov in
the
pub/bfrl/bentz/CEMHYD3D/version20/manual subdirectory .
The U.S. Department of Commerce makes no warranty, expressed or implied, to users of CEMHYD3D and associated computer programs, and accepts no responsibility for its use. Users of CEMHYD3D assume sole responsibility under Federal law for determining the appropriateness of its use in any particular application; for any conclusions drawn from the results of its use; and for any actions taken or not taken as a result of analyses performed using these tools.
Users are warned that CEMHYD3D is intended for use only by those
competent in the field of cement-based materials and is intended
only to supplement the informed judgment of the qualified user.
The software package is a computer model which may or may not have
predictive value when applied to a specific set of factual circumstances.
Lack of accurate predictions by the model could lead to erroreous
conclusions with regard to materials selection and design. All results
should be evaluated by an informed user.
The algorithms, procedures, and computer programs described in this report constitute a methodology for modelling the microstructural development and performance properties of cement-based materials. They have been compiled from the best knowledge and understanding currently available, but have important limitations that must be understood and considered by the user. The program is intended for use by persons competent in the field of cement-based materials and with some familiarity with computers. It is intended as an aid in the materials selection, optimization, and design process.