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NISTIR 6485

CEMHYD3D: A Three-Dimensional Cement Hydration
and Microstructure Development Modelling Package.
Version 2.0

Dale P. Bentz

April 2000
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, Maryland 20899

U.S. Department of Commerce

William M. Daley, Secretary

Technology Administration

Dr. Cheryl L. Shavers, Under Secretary of Commerce for Technology
National Institute of Standards and Technology
Raymond G. Kammer, Director


ABSTRACT

This user's manual provides updated documentation and computer program listings for version 2.0 of the three-dimensional cement hydration and microstructure development model (CEMHYD3D) developed at the National Institute of Standards and Technology. Originally documented and distributed in 1997, several substantial enhancements and modifications have been included in the new release. The following topics are covered in this documentation, as they were in the original version: acquisition and processing of two-dimensional scanning electron microscope and x-ray images; creation of a starting three-dimensional microstructure based on a measured particle size distribution for the cement powder and information extracted from the two-dimensional composite image; and execution of the cement hydration and microstructure development program. Additional noteworthy features of the new version of the model include: direct modelling of the induction period during cement hydration; isothermal, adiabatic, or user-programmed temperature curing conditions; a calcium silicate hydrate gel (C-S-H) whose molar stoichiometry and specific gravity (molar volume) vary with temperature; improved pozzolanic reactions between cement and silica fume (fly ash); and the incorporation of various forms of calcium sulfate (dihydrate, hemihydrate, and anhydrite) into the hydration model. In addition, a prototype internet-accessible database containing two-dimensional composite SEM images, quantitative phase analysis results, and measured cement particle size distributions is now available to provide key input information for the three-dimensional modelling process. Documented example datafiles are provided along with the examples given in the guide. Complete program listings are provided in the appendices. This manual and all of the computer programs it describes are freely available for downloading via anonymous ftp from NIST.



Keywords: Building technology, cement hydration, compressive strength, computer modelling, correlation, heat of hydration, image processing, microstructure, simulation.




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