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Kenneth A. Snyder

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Mailing Address

Kenneth A. Snyder, Ph.D.
Materials and Structural Systems Division
Engineering Laboratory
National Institute of Standards and Technology
100 Bureau Drive
Gaithersburg, MD  20899-8615   USA

You can download a pdf version of my Curriculum Vitae. (Last updated April 2014)

Dr. Snyder joined the Inorganic Building Materials Group in 1990 to study transport and reaction in random porous media. Studies of the diffusive transport of ionic species in cement paste pore solution have relied on characterizing the physical chemistry of transport and the thermodynamics of chemical reactions. The primary purpose of these studies is to develop reliable predictive models for the performance assessment of concrete structures exposed to the environment. Much of what has been learned has been incorporated into the 4SIGHT computer model that was sponsored by the Nuclear Regulatory Commission (NRC) for the assessment of underground concrete structures. Future applications may include assessment of grouts for isolating wastes incidental to reprocessing (WIR).

Through a comprehensive approach that incorporates the physical chemistry of concentrated electrolyte solutions, the diffusive transport of ionic species can be characterized by a single transport coefficient, the formation factor, regardless of the number of different ionic species present. To estimate the formation factor, Dr. Snyder is currently working toward a new test method that uses a single bulk conductivity measurement and pore solution expression, in conjunction with a predictive model for the electrical conductivity of concentrated multi-species electrolytes, also developed by Dr. Snyder.

Recently, Dr. Snyder has been leading an intramural Advanced Technology Program (ATP) project to develop the C-S-H Molecular Modeling Toolbox that includes computational tools and data for the molecular characterization of amorphous calcium silicate hydrate (C-S-H), the binding component of concrete. The conceptual approach has been to start with crystalline materials related to cements research (tobermorite, jennite, ettringite, etc.), develop molecular dynamics (MD) descriptions, calculate hydrogen atom dynamics at room temperature, and compare those dynamics to quasi-elastic neutron scattering (QENS) measurements. The tools in the web site (see below) include a free Parrinello-Rahman molecular modeling (PRMD) program written in FORTRAN-90, tools for manipulating crystallographic information files (CIF), and molecular dynamics descriptions of minerals relevant to cements research.

A research interest that originated prior to work at NIST is the stereological and statistical properties of entrained air voids in concrete. Relevant publications are given below, along with an experimental study of the time dependent freeze thaw susceptibility of low water:cement ratio concretes.

Dr. Snyder is a member of the following professional societies:
      American Physical Society (APS)
      American Society for Testing and Materials (ASTM)
      International Union of Testing and Research Laboratories for Materials and Structures (RILEM)

Transport Research - Experimental Projects

Research was conducted to investigate the viability of the Rapid Chloride Test (RCT) (see ASTM C 1202) as a tool for determining concrete conductivity. The results of the RCT were compared to impedance spectroscopy measurements. The results have been published in the Journal of Research of the National Institute of Standards and Technology has just published the paper, featuring the paper on the cover of the issue. A pdf version of the paper can be downloaded from the J. Res. NIST web site.

Transport Research - Standard Reference Material

Work is currently underway to characterize the properties of materials that are candidates for the establishment of a standard reference material (SRM) for transport measurements such as diffusion, migration (electrically driven diffusion), ion binding/sorption isotherms, and permeability. If your research program could benefit from the establishment of an SRM for transport measurements, please send me an email to that effect:

Here is an SEM micrograph of the ceramic microstructure. Click on the image to see a larger (215kb) version:

ceramic SEM micrograph

Air Void Stereology and Spacing

A chapter entitled, “The Stereological and Statistical Properties of Entrained Air Voids in Concrete: A Mathematical Basis For Air Void System Characterization,” has been published in Materials Science of Concrete VI, J. Skalny and S. Mindess, eds. The chapter collects information relevant to the characterization of entrained air voids in concrete: quantitative stereology; ASTM C 457 uncertainty analysis; inversion formulae for transforming among one-dimensional, two-dimensional, and three-dimensional data; estimating sphere diameter moments; thin section analysis; air void spacing; and the protected paste volume.

The book is published by the American Ceramic Society ( and can be purchased on the ACerS website.

ASTM C 09.65 (Petrography) - ASTM C 457 Uncertainty Calculation

Dr. Snyder is a member of ASTM Subcommittee C 09.65 (Petrography), and is the chairman of its Task Group that is developing a statistical precision statement for ASTM C 457 (Air Void Analysis of Hardened Concrete). Initially, this precision statement will be an optional portion of the test, but will be eventually included into the standard method. The Task Group will achieve its goal by simply assembling together the results of previous publications. There are three articles which contain most of the relevant material, and the fourth reference given below is a review chapter:

J.E. Hilliard and J.W. Cahn, "An evaluation of procedures in quantitative metallography for volume fraction analysis," Transactions of the Metallurgical Society of AIME 221, 344-352 (April 1961).

K.A. Snyder, K.C. Hover, and K. Natesaiyer, "An investigation of the minimum expected uncertainty in the linear traverse technique," Cement, Concrete, and Aggregates 13, 3-10 (Summer 1991).

R. Pleau and M. Pigeon, "Precision statement for ASTM C 457 practice for microscopical determination of air-void content and other parameters of the air-void system in hardened concrete," Cement, Concrete, and Aggregates 14, 118-126 (Winter 1992).

K.A. Snyder, K. Natesaiyer, and K.C. Hover, "The Stereological and Statistical Properties of Entrained Air Voids in Concrete: A Mathematical Basis For Air Void System Characterization," Materials Science of Concrete VI, J. Skalny and S. Mindess, eds., pp. 129-214, 2001. Purchase Book from the American Ceramic Society.

4SIGHT Program

A computer program was developed at NIST to facilitate assessment of concrete underground low-level waste disposal sites. The program estimates the vault permeability, diffusivity, and service life by using a transport model that incorporates the effects of leaching, corrosion, and sulfate attack. The program was written for the personal computer using the DOS operating system. An executable file, and supporting files, can be obtained from the NIST Anonymous FTP Site.

Recent Publications


D.P. Bentz, M.A. Peltz, K.A. Snyder, and J.M. Davis, "VERDiCT: Viscosity Enhancers Reducing Diffusion in Concrete Technology," Concrete International 31(1), 31–36, 2009.


D.P. Bentz, C.-J. Haecker, M.A. Peltz, and K.A. Snyder, "X-ray absorption studies of drying of cementitious tile adhesive mortars," Cement and Concrete Composites 30, 361–373, 2008

D.P. Bentz, K.A. Snyder, L.C. Cass, and M.A. Peltz, "Doubling the service life of concrete. I: Reducing ion mobility using nanoscale viscosity modifiers," Cement and Concrete Composites 30, 674–678, 2008.


K.A. Snyder and T.R. Kirkpatrick, "Energy transport along Fermi-Pasta-Ulam chains containing binary isotopic disorder: Zero temperature systems," Phys. Rev. B 73, 134204, 2006.

K.A. Snyder (Editor), C. Langton, B. Clark, C. Ferraris, and J. Dawson, "Engineered Infills for Concrete Barriers," NISTIR 7311, National Institute of Standards and Technology, Gaithersburg, MD, April 2006. Download PDF

K.A. Snyder, Z.Q. Lu, and J. Philip, "Long-term monitoring strategy for concrete-based structures using nonlinear Kalman filtering," J. Phys. IV (France) 136, 191-200, 2006.


K.A. Snyder, "Reply to the discussion by C. Shi of the paper "Estimating the electrical conductivity of cement paste pore solution from OH, K+, and Na+ concentrations," Cement and Concrete Research 35 (2), pp. 421-422 (2005) (PDF Version).

E. Samson, J. Marchand, K.A. Snyder, and J.J. Beaudoin, "Modeling ion and fluid transport in unsaturated cement systems in isothermal conditions," Cement and Concrete Research 35 (1), 141-153, 2005.

K.A. Snyder and J.W. Bullard, "Effect of Continued Hydration on the Transport Properties of Cracks Through Portland Cement Pastes in a Saturated Environment: A Microstructural Model Study," NISTIR 7265, National Institute of Standards and Technology, August 2005.


K.A. Snyder and T.R. Kirkpatrick, “Wave localization in binary isotopically disordered one-dimensional harmonic chains with impurities having arbitrary cross section and concentration” Phys. Rev. B 70, 104201, 2004.

Also published on the archive server.

K.A. Snyder and D.P. Bentz, “Suspended hydration and loss of freezable water in cement pastes exposed to 90% relative humidity,” Cement and Concrete Research 34 (11), 2045–2056, 2004. (PDF Version)

X. Feng, E.J. Garboczi, J.W. Bullard, D.P. Bentz, K.A. Snyder, P.E. Stutzman, and T.O. Mason, Final Report for: EPA: IAG No. DW-13-93903501-0 Expanding a tool for predicting chloride diffusivity in concrete so it can be used by manufacturers to evaluate the durability of concrete made with blended cements. Part I: Characterizing blended cement materials. National Institute of Standards and Technology Internal Report 7135; 37 p. August 2004. (PDF Version)


E. Samson, J. Marchand, and K.A. Snyder, "Calculation of ionic diffusion coefficients on the basis of migration test results," Materials and Structures 36 (257), 156–165, 2003. (PDF Version)

K.A. Snyder, X. Feng, B.D. Keen, and T.O. Mason, "Estimating the electrical conductivity of cement paste pore solutions from OH-, K+ and Na+ concentrations", Cement and Concrete Research 33, 793-798, 2003. (PDF Version)

K.A. Snyder, "Condition Assessment of Concrete Nuclear Structures Considered for Entombment," NISTIR 7026, National Institute of Standards and Technology, July 2003.


K.A. Snyder and J. Philip, "Concrete Degradation Modeling in the Evaluation of Entombment as a Decommissioning Option", SPECTRUM 2002, Reno, 2002. (PDF Version)

K.A. Snyder, "Estimating the 95-th percentile of the paste-void spacing distribution in hardened cement paste containing air entrainment," Frost Damage in Concrete, 1999 Minneapolis Workshop (RILEM), Ed. D.J. Janssen, M.J. Setzer, and M.B. Snyder, pp. 75-86, 2002. (PDF Version)

J. Marchand, E. Samson, K.A. Snyder, and J.J. Beaudoin, "Modeling ion transport mechanisms in unsaturated porous media," in Encyclopedia of Surface and Colloid Science, pp. 3466-3471, Marcel Dekker, 2002.


K.A. Snyder, "The relationship between the formation factor and the diffusion coefficient of porous materials saturated with concentrated electrolytes: Theoretical and experimental considerations," Concrete Science and Engineering, 3 (12), 216-224, (2001). (PDF Version)

K.A. Snyder and J. Marchand, "Effect of speciation on the apparent diffusion coefficient in nonreactive porous systems," Cement and Concrete Research, 31 (12), 1837-1845, (2001). (PDF Version)

K.A. Snyder, "Validation and Modification of the 4SIGHT Computer Program," NISTIR 6747, National Institute of Standards and Technology, May 2001.


R. Barbarulo, J. Marchand, K.A. Snyder, S. Prene, "Dimensional analysis of ionic transport problems in hydrated cement systems. Part 1. Theoretical considerations," Cement and Concrete Research 30, 1955-1960, 2000. (PDF Version)

K.A. Snyder, C. Ferraris, N.S. Martys, and E.J. Garboczi, "Using impedance spectroscopy to assess the viability of the rapid chloride test for determining concrete conductivity," Journal of Research of the National Institute of Standards and Technology 105 497-509, 2000. (PDF Version)

K.A. Snyder, "Effect of drying shrinkage cracks and flexural cracks on concrete bulk permeability," NISTIR 6519, National Institute of Standards and Technology, May 2000. (PDF Version)


K.A. Snyder and T.R. Kirkpatrick, "Influence of Anderson localization on the mode decay of excited nonlinear systems," Annalen der Physik (Leipzig) 8, SI-241-244, 1999. ( - 150Kb)

M. Simon, K.A. Snyder, and G.J. Frohnsdorff, "Advances in Concrete Mixture Optimisation. Keynote Paper," Concrete Durability and Repair Technology Conference. Proceedings. September 8-10, 1999, Scotland, UK, Thomas Telford Publishing, London, England, R.K. Dhir, M.J. McCarthy, Editors, 21-32, 1999. (PDF Version)

D.P. Bentz and K.A. Snyder, "Protected paste volume in concrete: Extension to internal curing using saturated lightweight fine aggregate," Cement and Concrete Research 29, 1863-1867, 1999 (PDF Version).

D.P. Bentz, E.J. Garboczi, and K.A. Snyder, "A hard core/soft shell microstructural model for studying percolation and transport in three-dimensional composite media," NISTIR 6265, National Institute of Standards and Technology, (Gaithersburg, MD) 1999. (PDF Version)


K.A. Snyder, " A numerical test of air void spacing equations," Advanced Cement Based Materials 8, 28-44, 1998. (PDF Version)


K.A. Snyder, Discussion of "The use of the flow length concept to assess the efficiency of air entrainment with regards to frost durability: Part I--Description of the test method," by R. Pleau and M. Pigeon, Cement, Concrete, and Aggregates 19, 116-119, 1997. (PDF Version)

M.J. Simon, E.S. Lagergren, and K.A. Snyder, "Concrete mixture optimization using statistical mixture design methods," Proceedings of the PCI/FHWA International Symposium on High Performance Concrete, Edited by L.S. Johal, New Orleans, pp. 230-244, October 1997. (PDF Version)

D. P. Bentz, K. A. Snyder, and P. E. Stutzman, "Microstructural modelling of self-desiccation during hydration," Self-Desiccation and Its Importance in Concrete Technology, Edited by B. Persson and G. Fagerlund, Proceedings of an International Research Seminar in Lund, pp. 132-140, June 1997. (PDF Version)

D. P. Bentz, K. A. Snyder, and P. E. Stutzman, " Hydration of Portland cement: The effects of curing conditions," Proceedings of the 10th International Congress on the Chemistry of Cement, Volume 2, Edited by H. Justnes, 2ii078 (8 pp.), 1997. (PDF Version)


D. P. Bentz, J. R. Clifton, and K. A. Snyder, "Predicting service life of chloride-exposed steel-reinforced concrete," Concrete International 18, 42-47, (December) 1996. (PDF Version)

K.A. Snyder, Discussion of "Influence of measurement technique on the air-void structure of hardened concrete," by T. Aarre, ACI Materials Journal 93, 512-514, 1996.

K.A. Snyder, J.R. Clifton, and J. Pommersheim, "A computer program to facilitate performance assessment of underground low-level waste concrete vaults," Scientific Basis for Nuclear Waste Management XIX, Materials Research Society Proceedings 412, pp. 491-498, 1996. PDF Version)


E.J. Garboczi, K.A. Snyder, J.F. Douglas, and M.F. Thorpe, "Geometrical percolation threshold of overlapping ellipsoids," Phys. Rev. E 52 (1), 819 (1995). (PDF Version)

K.A. Snyder and J.R. Clifton, "4SIGHT Manual: A Computer Program for Modelling Degradation of Underground Low Level Waste Concrete Vaults", NISTIR 5612, National Institute of Standards and Technology, (Gaithersburg, MD) 1995. (PDF Version)

D.P. Bentz, J.T.G. Hwang, C. Hagwood, E.J. Garboczi, K.A. Snyder, N. Buenfeld and K.L. Scrivener, " Interfacial zone percolation in concrete: Effects of interfacial zone thickness and aggregate shape," in Microstructure of Cement-Based Systems/Bonding and Interfaces in Cementitious Materials, edited by S. Diamond et. al. (Materials Research Society Vol. 370, Pittsburgh, 1995), pp 437-442. (PDF Version)

J.R. Clifton, J.M. Pommersheim, and K.A. Snyder, "Long-Term Performance of Engineered Concrete Barriers," NISTIR 5690, National Institute of Standards and Technology, (Gaithersburg, MD) 1995. (PDF Version)


K.A. Snyder and J.R. Clifton, "Measures of Air Void Spacing," Wiss. Z. Hochsch. Archit. Bauwes. (Weimar), 40, 155-157, 1994.

K.A. Snyder, J.R. Clifton, and L.I. Knab, "Freeze-Thaw Susceptibility of High Performance Concrete," Wiss. Z. Hochsch. Archit. Bauwes. (Weimar), 40, 139-142, 1994.

D.N. Winslow, M.D. Cohen, D.P. Bentz, K.A. Snyder, and E.J. Garboczi, "Percolation and pore structure in mortars and concrete," Cement and Concrete Research, 24, 25-37, 1994.

K. Natesaiyer, M. Simon, and K. Snyder, "Discussion on `Mean Spacing of Air Voids in Hardened Concrete,' by E.K. Attiogbe," ACI Mater. J. 91 (1), 123 (1994).

Recent Talks

"Relationship between formation factor and diffusion coefficient: Theory and Experiment," United Engineering Foundation, Advances in Cement and Concrete, Mont-Tremblant, Quebec, Canada, 24 Aug 2000.

"Estimating the 95-th Percentile of the Paste-Void Spacing Distribution in Hardened Cement Paste Containing Air Entrainment," Minneapolis Workshop on Frost Damage in Concrete, University of Minnesota, 28 June 1999.

" 'Spacings' in Binary and Ternary Composites," Department of Civil and Environmental Engineering, University of New Hampshire - 27 April 1999.

"The Particle-Particle and the Matrix-Particle Spacing Distributions for Non-Overlapping Spheres: Analytical and Numerical Results," Ecole Polytechnique Federale de Lausanne, Laboratory de Materiaux de Construction (Lausanne, Switzerland) - Oct. 1, 1997.

"The stereology of air voids in concrete," 7th ACBM Modeling Workshop, NIST (Gaithersburg, MD) - July 1996.

"A computer program to facilitate performance assessment of underground low-level waste concrete vaults," Materials Research Society Meeting (Boston, MA) - November 1995.



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