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Search Publications by: Edward Garboczi (Fed)

Displaying 151 - 175 of 208

Estimation of the Degree of Hydration of Blended Cement Pastes by a Scanning Electron Microscope Point-Counting Procedure

October 1, 2004

Author(s)

X Feng, Edward J. Garboczi, Paul E. Stutzman, T Mason

A scanning electron microscope (SEM) point-counting technique was employed to study the hydration of plain portland cement pastes and blended cement pastes containing fly ash or slag. For plain portland cement pastes, the results for the degree of cement

Shape Analysis of a Reference Cement

October 1, 2004

Author(s)

Edward J. Garboczi, Jeffrey W. Bullard

Recently, techniques for acquiring, analyzing, and using 3-D shape information for aggregates (sand, gravel) have been developed and demonstrated. These mathematical techniques, based on spherical harmonic coefficient analysis, have been applied to x-ray

Ultrasonic Evaluation Methods Applicable to Polymer Concrete Composites.

December 1, 2003

Author(s)

A Garbacz, Edward Garboczi

User Manual for Finite Element and Finite Difference Programs: A Parallel Version of NISTIR 6269 and NISTIR 6997

June 1, 2003

Author(s)

Robert B. Bohn, Edward J. Garboczi

This document contains the descriptions, algorithms, user information and listings of the parallel Fortran90/MPI versions of the suite of programs found in NISTIR 6269, Finite Element and Finite Difference Programs for Computing the Linear Electric and

Ultrasonic Evaluation Methods Applicable to Polymer Concrete Composites

April 1, 2003

Author(s)

A Garbacz, Edward Garboczi

Polymer composites (PC) appear as useful materials for repair and protection of building structures, as well as for manufacturing pre-cast elements. In the case of pre-cast elements as well as repair materials, the usefulness and durability of polymer

Impedance/Dielectric Spectroscopy of Electroceramics in the Nanograin Regime

December 3, 2002

Author(s)

N Kidner, Z J. Homrighaus, B J. Ingram, T Mason, Edward Garboczi

In the microcrystalline regime, the behavior of grain boundary-controlled electroceramics is well described by the brick layer model (BLM). In the nanocrystalline regime, however, grain boundary layers can represent a significant volume fraction of the

Computation of Linear Elastic Properties From Microtomographic Images: Methodology and Agreement Between Theory and Experiment

October 1, 2002

Author(s)

C H. Arns, M A. Knackstedt, W V. Pinczewski, Edward Garboczi

Elastic property-porosity relationships are derived directly from microtomographic images. This is illustrated for a suite of 4 samples of Fontainebleau sandstone with porosities ranging from 7.5 % to 22 %. A finite element method is used to derive the

Frequency-Dependent Electrical Mixing Law Behavior in Spherical Particle Composites

October 1, 2002

Author(s)

M A. Campo, L Y. Woo, T Mason, Edward Garboczi

The electrical properties of cement-based composites with mono-size conductive (steel) or insulating (glass) spherical inclusions were investigated by combined 2-point impedance spectroscopy and 4-point DC resistance measurements. The matrix was ordinary

Smart and Designer Structural Material Systems

October 1, 2002

Author(s)

K P. Chong, Edward Garboczi

An efficient civil infrastructure system is essential to every country's productivity and quality of life. Basic research and development in smart structures and designer materials has shown great potential for enhancing the functionality, serviceability

Three-Dimensional Mathematical Analysis of Particle Shape Using X-Ray Tomography And Spherical Harmonics: Application To Aggregates Used In Concrete

October 1, 2002

Author(s)

Edward J. Garboczi

The properties of composites made by placing inclusions in a matrix are often controlled by the shape and size of the particles used. Mathematically characterizing the shape of particles in three dimensions is not a particularly easy task, especially when

Computation of Linear Elastic Properties from Microtomographic Images: Methodology and Match to Theory and Experiment.

September 30, 2002

Author(s)

Edward J. Garboczi, C H. Arns, M A. Knackstedt, W V. Pinczewski

Elastic property-porosity relationships are derived directly from microtomographic images. This is illustrated for a suite of 4 samples of Fontainebleau sandstone with porosities ranging from 7.5% to 22%. A finite element method is used to derive the

Computation of the Linear Elastic Properties of Random Porous Materials With a Wide Variety of Microstructure

May 1, 2002

Author(s)

A P. Roberts, Edward Garboczi

A finite-element method is used to study the elastic properties of random three-dimensional porous materials with highly interconnected pores. We show that the Young's modulus, E, is practically independent of the Poisson's ratio of the solid phase, υs

E-Concrete? Believe It!

February 1, 2002

Author(s)

G J. Frohnsdorff, Edward J. Garboczi

In recent years, the complexity of concrete mixture proportioning has increased dramatically. New chemical admixtures, such as high-performance superplasticizers and shrinkage-reducing admixtures, have been introduced into the marketplace. Due to both

Computation of the Linear Elastic Properties of Random Porous Materials With a Wide Variety of Microstructure.

January 1, 2002

Author(s)

Edward J. Garboczi, A P. Roberts

Elastic Properties of Model Random Three-Dimensional Open-Cell Solids

January 1, 2002

Author(s)

A P. Roberts, Edward Garboczi

Most cellular solids are random materials, while practically all theoretical structure-property relations are for periodic models. To generate theoretical results for random models the finite element method (FEM) was used to study the elastic properties of

Intrinsic Conductivity of Short Conductive Fibers in Composites by Impedance Spectroscopy

December 1, 2001

Author(s)

A D. Hixson, L Y. Woo, M A. Campo, T Mason, Edward Garboczi

Electrical property measurements (DC conductivity, impedance spectroscopy) were employed to determine the intrinsic conductivities of short conductive fibers in cement matrix composites. Intrinsic conductivity determines the variation of overall

Intrinsic Viscosity and the Electric Polarizability of Arbitrarily Shaped Objects

December 1, 2001

Author(s)

M Mansfield, Jack F. Douglas, Edward Garboczi

The problem of calculating the electrical polarizability tensor αe of objects of arbitrary shape has been reformulated in terms of path integration and implemented computationally. The method simultaneously yields the electrostatic capacity C and the

Multi-Scale Microstructural Modeling to Predict Chloride Ion Diffusivity for High Performance Concrete

November 1, 2001

Author(s)

Dale P. Bentz, Edward J. Garboczi

As durability issues become increasingly prominent in concrete design, the need to predict the transport properties of a given concrete mixture becomes critical. For many degradation scenarios (corrosion, sulfate attack, etc.), the diffusion coefficient of

The Effect of Statistical Fluctuation, Finite Size Error, and Digital Resolution on the Phase Percolation and Transport Properties of the NIST Cement Hydration Model

October 1, 2001

Author(s)

Edward J. Garboczi, Dale P. Bentz

The National Institute of Standards and Technology (NIST) cement hydration model starts with a three-dimensional digital image of cement particles, and then uses cellular automaton rules to simulate the reaction of cement with water and the development of

Linear Elastic Properties of 2-D and 3-D Models of Porous Materials Made From Elongated Objects

September 1, 2001

Author(s)

S D. Meille, Edward Garboczi

Porous materials are formed in nature and by man by many different processes. The nature of the pore space, which is usually the space left over as the solid backbone forms, is often controlled by the morphology of the solid backbone. In particular

Sorptivity-Based Service Life Predictions for Concrete Pavements

September 1, 2001

Author(s)

Dale P. Bentz, M A. Ehlen, Chiara F. Ferraris, Edward J. Garboczi

The degradation of concrete pavements is often controlled by the transport of a deleterious species (chloride or sulfate ions, or water in the case of freeze/thaw) into the concrete. With this in mind, a three-year research project, funded by the Federal

Analysis of the Impedance Spectra of Short Conductive Fiber-Reinforced Composites

August 1, 2001

Author(s)

J M. Torrents, T Mason, A Peled, S Shah, Edward Garboczi

The presence of small amounts of short conductive fibers in a composite of finite matrix conductivity results in the subdivision of the one matrix impedance arc into two separate low and high frequency arcs in the complex impedance plane. These features

Analysis of the Impedance Spectra of Short Conductive Fiber-Reinforced Composites

August 1, 2001

Author(s)

Edward J. Garboczi, J M. Torrents, T O. Mason, A Peled, S P. Shah

Elastic Moduli of a Material Containing Composite Inclusions: Effective Medium Theory and Finite Element Computations

August 1, 2001

Author(s)

Edward J. Garboczi, J G. Berryman

Concrete is a good example of a composite material in which the inclusions (rocks and sand) are surrounded by a thin shell of altered matrix material and embedded in a normal matrix. Concrete therefore may be viewed as consisting of a matrix material

Electrical Impedance Spectra to Monitor Damage, During Tensile Loading, of Cement Composites

August 1, 2001

Author(s)

A Peled, J M. Torrents, T Mason, S Shah, Edward Garboczi

Conductive fibers can reinforce concrete and monitor damage leading to the development of a smart material. This work studied the correlation between the electrical (DC and AC) and mechanical properties of cement composites reinforced with conductive