1 

Virtual Cement and Concrete Testing Laboratory

Educational Version 2.0 User Guide

Jeffrey W. Bullard*

Materials and Construction Research Division 

National Institute of Standards and Technology 

Gaithersburg, Maryland USA 20899-8615

This document serves as the user’s guide for the educational version of the 

Virtual Cement and Concrete Testing Laboratory (VCCTL) software, version 2.0. 

Using the VCCTL software, a user may create 3D microstructures of cement paste 

made with clinker, calcium sulfate, fly ash, slag, limestone, and other materials. 

Hydration of these microstructures can be simulated under a variety of curing 

conditions, and the resulting hardened material can be analyzed for a number of 

properties including linear elastic moduli, compressive strength, and relative 

diffusion coefficients. A 3D packing of fine and coarse aggregates in mortar and 

concrete materials also can be created. The VCCTL software uses a relational 

database and plotting capabilities to facilitate viewing important characteristics of 

cement powders, supplementary cementitious materials, fillers, and aggregates. 

Finally, version 2.0 of the software gives the user control of the execution of his or 

her simulations.

Keywords: Building technology, cement hydration, computer modeling, 

concrete testing, microstructure, simulation, virtual laboratory

* Email address: jeffrey.bullard@nist.gov

NISTIR 7707

September 24, 2010

3

1 INTRODUCTION ............................................................................................... 5

1.1 DISCLAIMER..................................................................................................... 5

1.2 INTENT AND USE.............................................................................................. 6

2 INSTALLATION................................................................................................. 6

2.1 SOFTWARE PREREQUISITES.............................................................................. 6

2.2 TERMS OF USE AGREEMENT ............................................................................ 7

2.3 INSTALLATION FOLDER.................................................................................... 7

2.4 READY TO INSTALL.......................................................................................... 8

2.5 FINISHING THE INSTALLATION ......................................................................... 8

3 LAUNCHING AND CLOSING A SESSION ................................................... 9

3.1 CLOSING EVCCTL .......................................................................................... 9

4 REGISTERING AND LOGGING ON............................................................ 10

5 THE MAIN PAGE............................................................................................. 11

5.1 ANNOUNCEMENTS AND TUTORIALS............................................................... 11

5.2 THE MENU BAR ............................................................................................. 12

6 LAB MATERIALS............................................................................................ 13

6.1 CEMENTS ....................................................................................................... 13

View a cement ..................................................................................................... 13

6.2 SLAGS ............................................................................................................ 18

6.3 FLY ASHES..................................................................................................... 19

6.4 FILLERS.......................................................................................................... 20

6.5 AGGREGATES................................................................................................. 21

7 MIX..................................................................................................................... 22

7.1 PREPARE MIX ................................................................................................ 23

Specifying the solid cementitious binder............................................................. 23

Specifying the mix proportions ........................................................................... 24

Specifying simulation parameters....................................................................... 26

Saving the mix ..................................................................................................... 29

7.2 HYDRATE MIX ............................................................................................... 30
Thermal conditions ............................................................................................. 30

Aging ................................................................................................................... 31

Saturation conditions.......................................................................................... 32

Simulation parameters........................................................................................ 32

Executing the hydration simulation .................................................................... 33

8 MEASUREMENTS........................................................................................... 34

8.1 PLOT HYDRATED PROPERTIES ....................................................................... 34

8.2 MEASURE CEMENT/CONCRETE PROPERTIES .................................................. 36

Elastic Properties Results................................................................................... 38

Transport Properties Results.............................................................................. 39

9 MY OPERATIONS ........................................................................................... 40

Queued operations.............................................................................................. 40

Running operations............................................................................................. 41

Finished operations............................................................................................. 41

Canceled operations ........................................................................................... 42

10 MY FILES....................................................................................................... 42

10.1 MICROSTRUCTURE OPERATIONS................................................................. 43

10.2 DISPLAYING MICROSTRUCTURE IMAGES .................................................... 45

10.3 AGGREGATE OPERATIONS .......................................................................... 47

10.4 HYDRATION OPERATIONS........................................................................... 48

10.5 MECHANICAL PROPERTIES OPERATIONS ..................................................... 50

10.6 TRANSPORT PROPERTIES OPERATIONS ........................................................ 51

11 LOGOUT ........................................................................................................ 52

12 APPENDIX I................................................................................................... 53

13 APPENDIX II................................................................................................. 55

14 BIBLIOGRAPHY .......................................................................................... 57
5

1 Introduction

This user’s guide provides guidance for using the Virtual Cement and Concrete 

Testing Laboratory software, Educational Version 2.0 (eVCCTL 2.0). This virtual 

laboratory software consists of a graphical user interface and the underlying 

computer models and programs that allow users to create, hydrate, and estimate the 

performance of 3D cement-based microstructures from a desktop computer. The 

primary intent of this version is educational, especially to supplement the classroom 

experience of students studying civil engineering materials technology and 

materials science.

The main underlying programs for the eVCCTL software have been described 

previously [Bentz 1997, Bentz 2005, Garboczi 1998], and a large number of 

applications of these models has been published [Bentz and Haecker 1999, Bentz 

and Garboczi 1999, Bentz and Jensen 2000, Bentz and Feng, 2000, Bentz and 

Conway 2001, Bentz and Garboczi 1991, Bullard and Stutzman 2006, Bullard and 

Garboczi 2006]. This user guide therefore provides a detailed description of the 

user interface and a few examples of using eVCCTL for educational purposes.

1.1 Disclaimer

This software was developed at the National Institute of Standards and 

Technology (NIST) by employees of the Federal Government in the course of their 

official duties. Pursuant to Title 17 Section 105 of the United States Code this 

software is not subject to copyright protection and is in the public domain. The 

eVCCTL is an experimental system. NIST assumes no responsibility whatsoever for 

its use by other parties, and makes no guarantees, expressed or implied, about its 

quality, reliability, or any other characteristic. We would appreciate 

acknowledgment, such as an appropriate citation in a publication, if the software is 

used.

The U.S. Department of Commerce makes no warranty, expressed or implied, to 

users of eVCCTL and associated computer programs, and accepts no responsibility 

for its use. Users of eVCCTL 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 eVCCTL is intended for educational use only and is 

intended only to supplement the informed judgment of the user. The software 

package contains computer models which may or may not have predictive value 

when applied to a specific set of factual circumstances. Lack of accurate predictions 

by the models could lead to erroneous conclusions with regard to materials 

selection and design. All results should be evaluated by an informed user.
1.2 Intent and Use

The algorithms, procedures, and computer programs described in this guide 

constitute a prototype system for a virtual laboratory for the testing of cement and 

concrete. 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. eVCCTL is intended for use by persons competent in the 

field of cement-based materials and having some familiarity with computers

2 Installation

2.1 Software Prerequisites

The following requirements must be met for successful installation and running 

of this distribution of eVCCTL:

Microsoft Windows XP computer1

A minimum of 2 GB RAM and minimum hard disk space of 20 GB for long-term 

use of the software. Multiprocessor architectures with expanded shared memory, 

such as 16 GB, are commonly available and are recommended for the simultaneous 

execution of multiple simulations without loss of performance. 

(Service Pack 3). Other versions of Windows, 

such as Windows Vista or Window 7, may or may not be compatible with eVCCTL. 

Distributions are available for Linux operating systems; please contact the author 

for details.

Java Development Kit (JDK) 1.6, Update 20, or a more recent update. Go to 

http://www.oracle.com/technetwork/java/javase/downloads/jdk6-jsp136632.html to download the latest release of the JDK and follow the installation 

instructions given there.

Mozilla Firefox web browser, Version 3.0. Not required for installation, but 

other non-standard web browsers, such as Microsoft’s Internet Explorer, give 

erratic results when running the software.

To install eVCCTL, drag the evcctl-2.0-installer-windows.exe icon to 

the Desktop. Once it has been copied to the Desktop, double-click on the installation 

icon. A series of windows will guide you through the installation process as follows.

 

1 Certain commercial equipment and/or materials are identified in this report in order to 

adequately specify the experimental procedure. In no case does such identification imply 

recommendation or endorsement by the National Institute of Standards and Technology, nor does it 

imply that the equipment and/or materials used are necessarily the best available for the purpose.
Installation

7

2.2 Terms of Use Agreement

This dialog requires you to acknowledge the software disclaimer. If you accept 

the disclaimer agreement, you proceed with the installation by pressing the “Next” 

button. Otherwise, you will not be able to install and use the eVCCTL software.

2.3 Installation Folder

You may install eVCCTL in any location on your computer, provided that you 

have the adequate read/write permissions. The default path and folder is 

C:\Program Files\vcctl. You may accept that default or change it to another 

location. However, THE FINAL FOLDER ON THE PATH MUST BE NAMED vcctl

IN ALL LOWERCASE LETTERS. The software will not work properly if it is not 

installed in a folder named vcctl.
Installation

8

2.4 Ready to Install

The next dialog indicates that the software is ready to install. Clicking the 

“Next” button will begin the installation.

 

The last step of the installation is to unpack a rather large data folder. This step can 

consume several minutes, during which time it will appear that nothing is 

happening. Please be patient while the data folder unpacks.

2.5 Finishing the Installation

When the final step is completed, a final dialog box will appear. Just click on the 

“Finish” button to close this dialog box.
Launching and Closing

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3 Launching and Closing a Session

Before running eVCCTL for the first time, it is helpful to make Mozilla Firefox 

your default web browser. To do this, open Mozilla Firefox. If it is not already your 

default browser, a dialog box should appear asking you if you want to make it your 

default browser. Click “Yes” and then close the browser after it opens.

If the installation was successful, then eVCCTL can be launched from the 

Desktop by double-clicking on the Desktop icon labeled eVCCTL 2.0:

A Java console window will appear on the desktop, with a lot of information 

scrolling through it:

You must never close this console window while eVCCTL is running. Under 

ordinary circumstances, you may ignore this console window entirely. You may 

even minimize the window to your desktop tray if desired, but do not close it.

WARNING: You must never close the Java console window during an active 

session of eVCCTL. Doing so will cause eVCCTL to terminate immediately and, in 

some cases, a portion of the database that keeps track of your running operations 

may also become corrupted. It is safest to simply minimize the console window to 

your desktop tray and leave it there while you are using eVCCTL.

A few moments after the Java console window appears, your default web 

browser should open to the main login page of eVCCTL. Again, if this is not Mozilla 

Firefox, then you could observe unexpected or erratic behavior.

3.1 Closing eVCCTL

To properly shut down eVCCTL, follow these steps:
Launching and Closing

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1. Wait for all running operations to finish. Alternatively, you could cancel all 

the running operations if needed (this will be described in detail below).

2. Close the web browser

3. Open the Java console window and press Ctrl-C. After a brief pause, you 

will be asked, “Terminate batch job (Y/N)?”. Type “y” and press the 

Enter button. The Java console window will close.

4 Registering and Logging On

eVCCTL is a standalone desktop application, but it allows for some form of data 

privacy among multiple users on the same computer. For this reason, a session 

begins with logging on with a user name and password.

The first time you launch a session, you will not have a user name or password, 

so you must register with the database by clicking on the “Register!” link. This link 

will take you to a registration form shown below:

Enter your desired user name in the first box. If the user name is valid and has not 

been taken by someone else, you will see a green checkmark as shown. Otherwise, a 

red X will appear and you will be prompted to choose another name.

Next, enter your desired password. You must confirm the password in the 

adjacent text field, and if the two text fields agree, you will again see a green 

checkmark as shown.

Finally, enter your e-mail address in the bottom text box and confirm the 

address in the adjacent text box. E-mail addresses are not currently used by the 
Logging On

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application, but may be used in a future release to remotely notify users of 

completed operations, errors, or other important events.

When all the information has been entered properly (i.e., green checkmarks 

everywhere) then click the “Submit my registration” button. You will then be taken 

back to the login page, where you can enter your new user name and password.

5 The Main Page

A successful login will open the main page of the application. There are two 

parts to this page: (1) a section for announcements and streaming video tutorials, 

(2) a running Menu Bar in gray near the top.

5.1 Announcements and Tutorials

This section briefly introduces you to the major features of the eVCCTL 

application and also features a “Lab Tour”. The lab tour consists of a series of 

streaming video tutorials designed to step you through each of the major features 

and acquaint you with the procedures for running and monitoring different 

operations. Note that the lab tour requires (1) an internet connection and (2) a 

QuickTime plugin or other compatible streaming video plugin for your browser. 

Downloading and installing Apple’s free QuickTime player should automatically 

update your browser with the plugin.

The tutorials and this user guide are designed to be used together. One should 

view the tutorials first, then consult this guide for further details.
Menu Bar

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5.2 The Menu Bar

The menu bar is a persistent feature on all pages of the eVCCTL application, and 

enables you to quickly navigate from one part of the lab to another. The menu items 

are:

Home: The main page

Lab Materials: A multi-part page enabling you to examine the different 

materials stored in the eVCCTL database

Mix: A two-part page where you can make and hydrate virtual mixes of cement 

paste, mortar, or concrete

Measurements: A two-part page enabling you to plot the changes in properties 

of a material as it hydrates, or to calculate the linear elastic properties, compressive 

strength, and transport properties of your mix.

My Operations: Enables you to view the state of your requested operations 

(queued, running, finished, or canceled)

My Files: A listing of all your operations, complete with the ability to view any 

file in any operation or to export any file for further analysis by another application.

Logout: Provides a way to logout of the system or switch users.

Each of these menu items will be described in detail in the following sections.

Announcements 

and Tutorials

Menu Bar
Lab Materials

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6 Lab Materials

Click on the “Lab Materials” tab on the main menu, and you will be taken to a 

page that has a submenu with five tabs:

Each tab takes you to a page that enables you to view the properties of the 

relevant material component in the eVCCTL database.

6.1 Cements

This page enables you to view the inventory of cements stored in the eVCCTL 

database, along with a number of their physical and chemical properties. There are 

two sections to this page: (1) View a cement, and (2) View a cement data file. 

NOTE: Frequently you will see a small question mark icon, , near a feature on 

page. This is a tool-tip icon; clicking on it will open a blue textbox that gives brief 

information about the feature in question.

View a cement

The top section of the page has (1) a pull-down menu to select the cement that 

you want to view, (2) a view of a false-color scanning electron microscope (SEM) 

image of the cement which has been color-coded to reveal the spatial distribution of 

the mineral phases, (3) an text box with additional information about the cement, 

and (4) a collection of quantitative data on the cement, under the heading “Cement 

data” that is initially collapsed and hidden when the page opens.

Selecting a different cement in the pull-down menu will update each of these fields 

to display the relevant data for that cement. The characterization techniques used 

to generate these data have been described in detail in previous publications [Bentz 

and Stutzman 1994, Bentz and Stutzman 1999].

Segmented SEM image

This section shows a single image field from a scanning electron micrograph 

that has been colored to indicate the locations of the various cementitious mineral 

phases in the cement powder. A key to the color mappings is provided with each 

image.
Lab Materials

14

Information text box

The text box immediately below the image displays information about the 

cement, including a brief description, the original source of the cementitious sample, 

the date when the cement was either received or analyzed, and the fineness 

measured either by the air permeability test (Blaine, ASTM C204 [ASTM 2008]) or 

by laser diffraction from a dilute suspension of cement powder particles in 

isopropyl alcohol.

Cement data

This section is initially “collapsed” when the page opens. It can be displayed by 

clicking on the small grey triangle next to the “Cement data” subheading.

The fully displayed section contains a number of read-only text boxes and a 

couple of pull down menus that are described in the following list.
Lab Materials

15

PSD: This is a pull-down menu pointing to the file that contains the information 

on the particle size distribution (PSD) of the cement. In this educational version of 

VCCTL, selecting a different item on this menu has no effect on the cement. The 

only way to modify the PSD of a cement is to modify the file associated with the 

cement (e.g., cement140 psd as shown in the figure). Please refer to the next 

section, View a cement data file, for more information on how to modify the PSD of 

a cement.

Alkali: This is a pull-down menu pointing to the file that contains the 

information on the alkali content of the cement, including the total equivalent K2O 

and Na2O content as well as the readily-soluble fraction of each. In this educational 

version of VCCTL, selecting a different item on this menu has no effect on the 

cement. The only way to modify the alkali content of a cement is to modify the file 

associated with the cement (e.g., alkalicem140 as shown in the figure). Please 

refer to the next section, View a cement data file, for more information on how to 

modify the alkali content of a cement.

PFC: PFC is an acronym for Phase Fractions in Clinker. The data are displayed 

as either four or six rows of two columns each. The first row is for alite (C3S2

 

2 Where it is convenient and unlikely to cause confusion, conventional cement chemistry 

notation is used in this guide. C = CaO, S = SiO2, A = Al2O3, F = Fe2O3, H = H2O

), the 
Lab Materials

16

second row for belite (C2S), the third row for tricalcium aluminate (C3A), and the 

fourth row for tetracalcium aluminoferrite (C4AF). If a fifth and sixth row are 

present, they represent arcanite (K2SO4) and thenardite (Na2SO4), respectively. The 

left column indicates the volume fraction of the associated phase, on a total clinker 

volume basis, and the right column indicates the surface area fraction of the 

associated phase, on a total clinker surface area basis. The sum of each column 

should be 1.0.

X-ray Diffraction Data: This field displays the results of a quantitative X-ray 

powder diffraction analysis of the cement using Rietveld refinement. The data are 

not used by the eVCCTL software, but are merely present to provide additional 

information to the user.

Sil, C3S, C4AF, C3A, Na2SO4, K2SO4, Alu: These fields display the kernels for the 

two-point correlation function calculated for the combined silicates, C3S, C4AF, C3A, 

Na2SO4, K2SO4, and combined aluminates, respectively. These data ares used to 

distribute the clinker phases among the cement particles that are created when a 

mix is requested. One or more of these fields may be blank.

In the educational version of VCCTL, none of these cement data may be 

permanently changed in the database. The text boxes are read-only and may not be 

modified. However, certain properties of a cement may be temporarily modified at 

the time when a mix is made (see Section 7.1 for more information).

Mass fractions of sulfates

Three calcium sulfate carriers are recognized in eVCCTL: gypsum (calcium 

sulfate dihydrate), bassanite (hemihydrate), and calcium sulfate anhydrite. This 

section shows the mass fractions of each of these carriers found in the cement, on a 

total solids basis. In eVCCTL, these values may not be permanently modified in the 

database. However, they may be temporarily changed at the time when a mix is 

made (see Section 7.1 for more information).

View a cement data file

This section is also collapsed when the page first opens. It can be displayed by 

clicking on the small grey triangle next to the heading “View a cement data file”.
Lab Materials

17

There are a number of different auxiliary data files that are used by eVCCTL to 

make mixes or simulate the hydration of materials, and this section enables the user 

to view and modify some of those data files. The left text box contains the actual 

data, and the right text box contains information on the formatting of the data file. 

Each type of data file is described in the following list:

psd: These files contain information on the particle size distribution of the 

cement powder. The left column is the equivalent spherical diameter in 

micrometers (i.e., the diameter of a sphere having the same volume as the 

irregularly shaped particle), and the right column is the volume fraction of particles 

having an equivalent spherical diameter between that row and the following row. 

Therefore, these data describe a discrete probability density function (PDF) for the 

particle sizes.

alkali_characteristics: These files contain information on the potassium and 

sodium content of the cement on a total solids basis. This data file has four or six 

rows. The first and second rows are the mass per cent equivalent total Na2O and 

K2O, respectively. The third and fourth rows are the mass per cent readily soluble 

Na2O and K2O, respectively. The fifth and sixth rows, if they are present, are the 

mass per cent Na2O and K2O added as NaOH and KOH to the mix water, respectively.

slag_characteristics: There is only one of this kind of data file in eVCCTL. It 

describes the physical and chemical properties of both the slag and the slag gel 

hydration product. This file can be modified but will have no effect on the 

calculations made by eVCCTL. More information on the meaning of each parameter 

is provided in Section 6.2 on Slags below.

parameter_file: There is only one of this kind of file in eVCCTL. It catalogs the 

values of several dozen empirical parameters that are used by the program that 

simulates hydration of cement pastes. The meaning of each parameter is beyond 

the scope of this guide.

chemical_shrinkage_file: In the full version of VCCTL, users can calibrate the 

time scale for hydration simulations using experimentally determined chemical 

shrinkage data. This file contains the measured data as an example, but this 

calibration feature is disabled in eVCCTL, so changing the file will have no effect on 

the calculations.

calorimetry_file: In the full version of VCCTL, users can calibrate the time scale 

for hydration simulations using experimentally determined isothermal calorimetry 

data. This file contains the measured data as an example, but this calibration feature 

is disabled in eVCCTL, so changing the file will have no effect on the calculations.

Users may alter any of the data files and save them by pressing the “Save” 

button below the text boxes. For example, if a user manually modifies the 

cement140 psd data file and saves the changes, the modified PSD data will be 

used any time that cement140 cement is used to create a mix.

A copy of each original data file is stored in the database, so if a user wishes to 

return to the original data, the “Restore” button can be pressed, followed by the 

“Save” button. NOTE: The user must press the “Save” button after restoring 

original data or the previously modified data will remain.
Lab Materials

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6.2 Slags

The slag material inventory page consists of a pull-down menu to select the slag 

to view (there is only one slag in the eVCCTL database), along with a textbox 

displaying the specific gravity of the slag and a second pull-down menu pointing to 

the file for particle size distribution. Again, in eVCCTL these fields cannot be 

modified or, in the case of the PSD file, can only be modified indirectly by changing 

the contents of the associated PSD file (e.g. cement141 psd) on the Cements page.

A second section, “Slag properties and description” is initially collapsed when 

the page opens, but can be expanded by clicking on the small grey triangle next to 

the heading. This section displays the chemical and physical properties that the 

eVCCTL hydration model needs to be able to simulate the hydration of the slag in a 

blended cement. The properties are self-explanatory, and the tool-tip can be used to 

gain further information on some of them. Notice that some of the properties relate 

to the slag itself, some relate to the slag “hydration product”, and some must be 

specified for both the slag and the hydration product. In eVCCTL, these properties 

cannot be edited, but are displayed primarily for informational purposes.
Lab Materials

19

6.3 Fly Ashes

The fly ash material inventory page consists of a pull-down menu to select the 

fly ash to view (there is only one fly ash in the eVCCTL database), along with a 

textbox displaying the specific gravity of the fly ash and a second pull-down menu 

pointing to the file for particle size distribution. Again, in eVCCTL these fields 

cannot be modified or, in the case of the PSD file, can only be modified indirectly by 

changing the contents of the associated PSD file (e.g. cement141 psd) on the 

Cements page. Unlike slags, however, fly ash materials consist of multiple phases. 

Therefore, another field is displayed to indicate whether the phases are to be 

distributed on a particle basis (i.e. each fly ash particle is a single phase) or on a 

pixel basis (i.e. each particle contains multiple phases distributed randomly pixel by 

pixel). In eVCCTL, the fly ash in the database is set to distribute its phases on a 

particle basis. Although the user can click on the other radio button to choose the 

pixel-based distribution, this has no real effect because the ability to save the 

modified fly ash is disabled in this educational version.

Like the slag inventory page, the fly ash page has a second section, initially 

collapsed when the page opens, for other fly ash properties. In this case, the fly ash 

properties are simply the volume fraction of the various phases comprising the fly 

ash. The seven eligible phases are shown in the accompanying figure. Again, the 

values in the table cannot be edited in eVCCTL but are displayed only for 

informational purposes. The phase distribution shown is similar to a fly ash that 

was characterized in 2004 at NIST [Feng and Garboczi 2004].
Lab Materials

20

6.4 Fillers

Inert fillers have only two properties of interest: specific gravity and particle 

size distribution. The inventory of fillers in eVCCTL consists of three materials, (1) 

α-quartz (SiO2) with a specific gravity of 2.62, (2) corundum (Al2O3) with a specific 

gravity of 4.05, and (3) periclase (MgO) with a specific gravity of 3.78. All three 

inert fillers have cement141 psd to describe their particle size distribution. In

eVCCTL, these properties cannot be changed.
Lab Materials

21

6.5 Aggregates

Coarse and fine aggregates are included in the eVCCTL database for the 

purposes of creating mortar and concrete mixes. Three coarse aggregate sources 

and four fine aggregate sources have been characterized for particle shape, specific 

gravity, and linear elastic moduli. The shape characterization procedure involves 

capturing a 3D image of a packing of the aggregate particles, using X-ray computed 

tomography, and then analyzing the shape of individual particles by spherical 

harmonics. The procedure is described in [Garboczi 2002].

The aggregate materials inventory consists of one section for coarse aggregates 

and one for fine aggregates. Both sections are collapsed when the page first appears 

and can be opened by clicking on the small grey triangle next to the respective 

headings. Each section is identical except for the materials it displays, so the 

accompanying figures will illustrate the features for the fine aggregates only.

When the coarse or fine aggregate section is expanded, there is a pull-down 

menu to choose which aggregate source to examine. Below that is a section showing 

a color photograph of a small sample of the aggregate and an accompanying table 

that summarizes the gross shape data for the aggregate such as the distribution of 

ratios of length to width (L/W) and width to thickness (W/T)3

 

3 In aggregate terminology, the length is the greatest linear dimension of an aggregate particle, 

the width is the greatest linear dimension in any direction perpendicular to the length axis, and the 

thickness is the greatest linear dimension the direction that is simultaneously perpendicular to both 

the length and the width.

. In the table, the 

mean and range of L/T and W/T are provided, and below that a table showing the 

distribution of particles with given L/T and W/T. These data come from the 

spherical harmonic analysis, but it is useful to remember that the spherical 
Lab Materials

22

harmonic data in the database contain much more information about particle shape, 

enough to reproduce the 3D shape of a given particle of any size and rotational 

orientation in space.

Below the image and shape data, some physical properties of the aggregate are 

displayed, including the specific gravity, bulk modulus (in GPa) and shear modulus 

(in GPa). These fields cannot be edited by the user, but are displayed for 

informational purposes and so the user can see the values used for input in the 

calculations involving these materials. Finally, a text box displays other information 

about the aggregate, including a descriptive name, the source and intended use of 

the aggregate and, in some cases, the basic mineralogical content.

7 Mix

With some knowledge of the types of materials and their properties that are 

stored in the eVCCTL database, we turn now to the part of the software that enables 

one to create mixes and cure them. This part of the software is accessed through the 

“Mix” tab on the main menu bar, and has a submenu for accessing two pages, one for 

creating a mix and one for simulating its hydration.

A Note on the Operating Principles of VCCTL Programs: Before describing 

these parts of the software, it is useful to understand the underlying operating 

principles of the programs that create the mixes and simulate hydration. VCCTL 

software (both eVCCTL and the full VCCTL version) are based on a “digital image” 

approach to representing microstructure. In this approach, microstructures are 

mapped onto a regular 3D grid of cubic volume elements, often called pixels or 

voxels. For cement pastes, each voxel is 1 μm on a side, but for larger scale packings 

of fine or coarse aggregates the voxel size depends on the smallest particle that will 

be placed. When a cement paste microstructure is created on this voxel grid, each 

voxel is occupied by exactly one “phase” (e.g., C3S, slag, saturated porosity, etc.). In 

this way, the programs that lie behind the VCCTL user interface are able to 

accurately reproduce microstructures that capture the desired phase assemblage, 

water/cement ratio, particle size and shape distribution, and surface areas.
Prepare Mix

23

Simulating hydration of these initial microstructures involves rule-based 

interactions among the voxels in the microstructure. The rules are designed to 

mimic the various chemical reactions and mass transport that occur during 

hydration. As a result, the 3D digital image microstructure is incrementally changed 

to simulate microstructure development. This process introduces new hydration 

product phases such as C-S-H gel, CH, ettringite, and several others.

The full details of the operating principles for the digital image approach can be 

found in other publications [Bentz 1997, Bentz 2005]. A discussion of 

computational tools that have been developed to analyze the properties of digital 

image microstructures can be found in [Garboczi and Bentz 1999]. Some of the 

artifacts and limitations of digital image approaches are described in [Garboczi and 

Bentz 2001].

7.1 Prepare Mix

This page is used to create an initial 3D cement microstructure consisting of 

particles of cement clinker, calcium sulfate carriers, and other selected compounds 

in water, as well as simulated packings of fine and coarse aggregates when the paste 

is acting as the binder in a mortar or concrete. There are three main steps involved 

in creating the mix: (1) specifying the solid cementitious binder properties, (2) 

specifying the mix proportions of the solid portion of the binder with water and 

aggregate, and (3) specifying the system size and other miscellaneous simulation 

parameters. Each of these steps is now described.

Specifying the solid cementitious binder

The principal component of the binder is one of the portland cements, which 

may be selected from among those in the database using the pull-down menu 

selector. Once the cement is selected, the volume fractions and surface area 

fractions of the clinker minerals may be modified for the mix if desired by expanding

the section “Modify phase distribution of the clinker”. The default values displayed 

in the tables are those stored in the database for the corresponding cement when it 

was characterized as already described. The table keeps a running sum of the two 

columns, which should both add to 1.0. If the user modifies the values in the 

columns in such a way that one or both columns do not sum to 1.0, the columns will 

be re-normalized to 1.0 when the mix is created.

The chosen cement also has default values for the mass fractions of the calcium 

sulfate carriers (dihydrate, hemihydrate, and anhydrite) which can be reviewed and 

modified by expanding the section headed “Modify calcium sulfate amounts in the 

cement”. Remember that the displayed values are given on a total solid cement 

basis, and that all values are displayed as fractions, not percentages.
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The last part of specifying the solid binder is to select the type and quantity of 

any supplementary cementitious materials (SCMs) or fillers. The categories for 

these materials are (1) fly ash, (2) slag, (3) inert filler, (4) silica fume, (4) limestone 

(CaCO3), and (5) free lime (CaO). For fly ash, slag, and inert filler, the materials may 

be selected from the accompanying pull-down menu selector from those available in 

the database, as already described in Section 6. For silica fume, limestone, and free 

lime, the composition and specific gravity are assumed fixed, and the user is asked 

only to specify the particle size distribution by selecting the file for the PSD from one 

of those in the database. Recall that the PSDs associated with each file can be 

viewed on the Lab Materials page as described in Section 6.1. Once the material and 

characteristics are selected, the user may specify either the mass fraction or volume 

fraction that the material will occupy on a total solid binder basis. This is equivalent 

to specifying a replacement level for each component. Note that the total fraction of 

cement in the binder is reduced as the fractions of these other materials is 

increased. Note, if the mass fraction is specified, then the volume fraction will be 

automatically calculated and displayed based on the specific gravities of all the 

components. Similarly, specifying the volume fraction will cause the mass fraction 

to be automatically calculated and displayed.

Specifying the mix proportions

When the solid portion of the binder is specified, the next section can be used to 

specify the water/binder mass ratio (w/b) using the pull-down menu selector. The 

options for the w/b value cover the range normally used for concrete and also 

include the value 0.485, the latter which is used for ASTM C109 mortar cube 

compressive strength specimens [ASTM 2008]. Read-only text fields for viewing the 
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25

mass fractions and volume fractions of solid binder and water corresponding to the 

selected w/b ratio.

This section also includes the option to add coarse or fine aggregate to the mix 

to create a mortar or concrete. To add aggregate, click on the checkbox next to the 

coarse or fine aggregate. When this is done, the text boxes for the mass fraction and 

volume fraction, initially disables, become enabled and the user can type in the 

desired mass fraction or volume fraction, on a total mortar or concrete basis.

In addition, when one of the aggregate checkboxes is selected, a new section 

appears below it, intially collapsed, called “Change properties”. Expanding this 

section enables the user to specify the aggregate source, specific gravity, and 

grading (or size distribution).
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Notice that changing the specific gravity of the aggregate causes the volume 

fractions of the aggregate, binder, and water all to change in response. Finally, 

aggregate grading is displayed in tabular form using the customary sieve 

designations to indicate the size bins that are used. The user may specify the 

grading by typing in the mass fraction of aggregate retained in each sieve. The sum 

of the mass fractions in the table should be 1.0, but it will be normalized to 1.0 if not. 

eVCCTL comes with one pre-selected fine aggregate grading that corresponds to the 

grading specified in the ASTM C 109 mortar cube compressive strength test [ASTM 

2008]. The coarse aggregate section also comes with a default aggregate grading, 

but the default grading does not correspond to any particular test.

Note: In the full version of VCCTL, the aggregate grading specified manually by 

the user can be saved in the database for easy retrieval in subsequent mixes, but in 

eVCCTL this feature has been disabled.

Specifying simulation parameters

After the mix proportions are specified, the user may optionally select or modify 

any of several simulation parameters, each of which is now described.

Random number generator seed: When the virtual microstructures are 

created, random numbers are used to randomly select the positions of particles as 

they are added, to stochastically distribute the clinker phases within the constraints 
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27

of the two-point correlation functions, and a variety of other tasks. The random 

number generator used in the VCCTL programs require an initial “seed” value, 

which must be a negative integer. Under ordinary circumstances, the seed value 

will be chosen automatically, but the user may also specify a particular seed value, if 

desired, by checking the box and typing a negative integer in the text box. If a nonnegative integer number is typed in the box, it will be ignored.

Real particle shapes: Check this box if you want the cement particles in the 

microstructure to have realistic shapes. As already described, the 3D shapes of 

aggregate particles have been characterized by spherical harmonic analysis and 

stored in the VCCTL database to recreate realistic aggregate packings. A nearly 

identical procedure has been used to characterize the particle shapes of several 

different portland cement powders, except that X-ray microtomography is required 

to obtain sufficient spatial resolution to characterize the particles using spherical 

harmonics [Garboczi and Bullard 2004]. To obtain realistic cement particle shapes 

in the microstructure, mark the check box and select the shape set from the pulldown menu selector. Note that requesting realistic particle shapes will require 

significantly more time to create the microstructure, sometimes two or three times 

as long.

Note: If the real particle shape checkbox is not selected, then the cement 

particles all will be digitized spheres.

System size for the binder: The number of voxels in each linear dimension of 

the 3D grid can be chosen by the user, the default value being 100 in each direction. 

As already mentioned, each cubic voxel in the cement paste is 1 μm on a side, so the 

number of voxels in each dimension is numerically equal to the linear dimension. 

Note that larger values of the linear dimensions will require significantly more time 

to create the microstructure; the time required to create a microstructure scales 

linearly with the number of voxels in the grid, which can be calculated according 

to the equation

where , , and are the numbers of voxels in the cement paste in the x, y, 

and z directions of the grid.

System size for the concrete: This section appears only if fine or coarse 

aggregate is being added to create a mortar or concrete. The default values for the 
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linear dimensions and resolution are determined by the grading specified by the 

user. However, these values may be changed subject to the following constraints:

The minimum linear dimension of the concrete system must be at least twice as 

big as the opening of the coarsest sieve that retains any aggregate.

The resolution chosen from the pull-down menu selector must be no more than 

half the opening of the finest sieve that retains any aggregate.

These constraints are used to ensure that each aggregate particle in the grading 

fits into the box and can be approximately visualized in the packing. If either of 

these constraints is violated, an alert box will appear with a message describing 

which constraint was violated. Clicking the “OK” button on the dialog box dismisses 

it and also causes the offending dimension or resolution to be reset to an acceptable 

value that satisfies the constraints.

Note: Even when coarse or fine aggregates are included in the mix, the 3D 

aggregate packing is not created by default. To override this behavior and force the 

aggregate packing to be created, the checkbox next to “Create the 3D aggregate 

packing” must be checked.

Note: Creating a virtual aggregate packing often takes significant 

computational resources because the shapes are created individually from the 

spherical harmonic coefficients stored in the database. As with the cement paste 

system, the time required to create a 3D aggregate packing will scale linearly with 

the number of voxels in the aggregate packing, which can be calculated 

according to the equation:

where , , and are the linear dimensions of the grid in mm, and is the 

resolution in mm/voxel.

Note: If fine or coarse aggregates are included in the mix, then a flat “slab” of 

aggregate will be inserted parallel to the yz plane in the center of the cement paste 

microstructure, regardless of whether or not an aggregate packing is requested. 

This aggregate slab is inserted to simulate the packing limitations of cement 

particles near an aggregate surface, the phenomena leading to the interfacial 

transition zone (ITZ) in mortar and concrete. The properties of the ITZ are 

important in determining the mechanical properties and transport properties of 

mortar and concrete [Bentz and Garboczi 1999b], so it is important that the ITZ be 

recreated in the virtual cement paste microstructure so that its properties can be 

subsequently computed and incorporated into calculations of mortar and concrete 

properties. 
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Saving the mix

The last steps in creating a mix are to give the mix a unique name (i.e. one that 

does not already exist in the database) and execute the mix creation program. Type 

a name for the mix in the text box provided. Names can include upper case or lower 

case letters, numbers, or spaces. After typing the proposed name and clicking 

anywhere outside the text box, the software will validate the name. A green 

checkmark next to the name indicates that it is valid.

On the other hand, a red X indicates that the name has already been used for an 

existing mix.

Once a valid name has been chosen, click on the “Create the mix” button to begin 

creating the mix. The status of the mix operation can be checked on the “My 

Operations” page, as described in detail in Section 9.
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7.2 Hydrate Mix

The NIST cement hydration model [Bentz 1997, Bentz 2005] operates directly 

on 3D digital images of cement paste microstructures created as described earlier. 

Execution of the model requires a starting microstructure, information about the 

curing conditions (thermal conditions and moisture state), and the frequency at 

which to output various data for later analysis.

To begin hydrating a mix, first select the mix name from the pull-down menu 

selector. This is the name chosen when the mix was created. In addition, at this 

point you may specify the apparent activation energies of the three major “net” 

hydration processes that can occur: (1) cement hydration, (2) pozzolanic reactions, 

including fly ash hydration and silica fume reactions and (3) slag hydration. The 

default values that are provided reflect sensible values based on a survey of the 

literature (for example, see ASTM C 1074 [ASTM 2008]). The section for modifying 

the activation energies is collapsed when the page first opens, but may be expanded 

by clicking on the small grey triangle next to the heading “Reaction activation 

energies”.

Thermal conditions

The thermal condition of the hydrating material may be (1) isothermal, (2) 

semi-adiabatic, or (3) adiabatic.
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Isothermal: The material is in diathermal contact with a constant-temperature 

reservoir and heat transfer is sufficiently rapid to maintain the material at the 

temperature of the reservoir. The default value is 25 °C.

Semi-adiabatic: Heat generated by hydration reactions is transferred to a 

surrounding reservoir that is at a fixed temperature, but the transfer rate is slow 

enough that some of the generated heat causes the material temperature to 

increase. If this option is selected, then not only the initial temperature of the 

material must be specified (default 25 °C), but also the temperature of the 

surrounding reservoir (default 25 °C) and the effective heat transfer coefficient, in 

units of W/K (default 10.0).

Adiabatic: The material is perfectly insulated from its environment, so all the 

heat generated by hydration reactions is used to increase the temperature of the 

material. If this option is chosen, only the initial temperature of the material must 

be specified. The default value is again 25 °C.

Aging

This section is used to specify the total length of time that the material should 

be hydrated. The time is specified by entering the desired number of days in the 

text box provided or, alternatively, by specifying a maximum degree of hydration at 

which the simulation will terminate.

The other required element is the “time conversion factor”, which has units of 

h/cycle2. The NIST hydration model proceeds in repeated “cycles” of dissolution, 

diffusion, and reaction. These cycles have no intrinsic time scale, so one must define 

an assumed relationship between time (in hours) and computational cycles. In the 

current version of eVCCTL, hydration time, t, in hours is related to the number of 

computational cycles, n, according to the parabolic relation
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where β is a time conversion factor that must be specified. The default value of 3.5 × 

10-4 is a value that works reasonably well for a number of cements, but which is not 

optimized to any particular cement. To optimize the time conversion parameter, a 

calibration of the model against some experimental measure of the degree of 

hydration, chemical shrinkage, or isothermal heat release should be made.

Note: The parabolic relation employed for the time scale is not used for any 

fundamental reason, but only because it often provides a reasonable fit to 

experimental measurements of the progress of hydration with time, provided that 

the time conversion factor is calibrated sufficiently well.

Saturation conditions

The two moisture condition options are saturated or sealed. The saturated 

condition means that the cement paste is in contact with a reservoir of excess water. 

As free water in the capillary pores is consumed by the hydration reactions, it is 

immediately replaced by water from the reservoir. Note, however, that once the 

capillary porosity reaches its percolation threshold and becomes disconnected, 

water replacement is no longer possible even under saturated conditions. The 

sealed condition means that free water consumed during hydration is not replaced. 

Instead, the capillary pores are progressively emptied of water, starting in those 

pore regions with the largest effective diameters.

Simulation parameters

This section is collapsed when the page first opens because it will not usually be 

of interest. It can be expanded by clicking on the small grey triangle next to the 

heading. The only simulation parameter that can be modified in eVCCTL is the value 

of the seed for the random number generator. See the discussion on random 

number seeds in Section 7.1 for a description.

Data output

This section is collapsed when the page first opens. It can be expanded by 

clicking on the small grey triangle next to the heading. This section can be used to 

specify how frequently (in hours of simulated age) the hydration model will output 

certain properties to data files.

Evaluate percolation of porosity ... Percolation properties like this one tend to 

consume significant computational time to calculate because the calculations 
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involve nested iterations over most or all of the system voxels. Therefore, it is 

recommended that percolation properties not be evaluated any more often than 

necessary. The percolation state of the capillary porosity determines the point at 

which water can no longer be absorbed from an external source to maintain 

saturated conditions. Once the hydration model detects that the pore space is 

depercolated, this calculation will no longer be made no matter what value is typed 

into the text box. The default value is 1.0 h.

Evaluate percolation of total solids ... This property provides an indication of 

initial setting time, so it should be evaluated fairly frequently to obtain a reasonable 

assessment of setting time of a material. The default value is 0.5 h.

Output hydrating microstructure ... The state of the entire 3D microstructure 

can be saved at regular intervals during the hydration process. Subsequent 

calculations of the linear elastic moduli, compressive strength, and transport 

properties of the material at a particular state of hydration can only be made if the 

microstructure is available at that state. The default value is 72.0 h.

Executing the hydration simulation

To execute the simulated hydration operation, provide a unique name for the 

operation in the box next to “File name” at the bottom of the page. The default name 

is the name of the mix with the prefix “HydrationOf-“ prepended. The default name 

can be modified, but must be unique. The software validates the name before and 

will indicate a green ✓ (okay) or a red � (invalid) next to the name. Once a valid 

name is selected, click on the “Hydrate the mix” button to launch the operation. The 

status of the hydration operation can be checked on the “My Operations” page, as 

described in detail in Section 9.

Note: One or more hydration operations for a particular mix can be requested 

and launched even before the mix operation has been completed. If the mix 

operation is still running when the hydration request is made, a message will appear 

saying,

“The mix you want to hydrate is not ready now. The hydration will begin as 

soon as the mix preparation is finished”.

In other words, the hydration operation is queued to run as soon as the mix 

operation completes and a starting microstructure is available.
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8 Measurements

In eVCCTL, there are 61 properties that are continuously tracked during a 

hydration operation, and all of them are stored in a data file that can be accessed for 

online plotting or exporting to a spreadsheet for further analysis. See Appendix II

for a listing of all the available “hydrated properties”. In addition, the linear elastic 

moduli, compressive strength and transport properties of cement pastes, mortars, 

or concretes can be calculated on hydrated microstructures. The Measurements 

page provides access to all these virtual measurement capabilities.

Clicking on the “Measurements” tab of the main menu bar opens a page with a 

submenu having two options: (1) Plot Hydrated Properties, and (2) Measure 

Cement/Concrete Properties.

8.1 Plot Hydrated Properties

This page provides a flexible inline plotting capability for plotting the evolving 

properties of a hydrating material. To create a plot, first select the desired x-axis 

property from the pull-down menu selector. The default x-axis is “Time”, in 

hours,but any other hydrated property can be selected as well.

With the x-axis selected any number of properties can be simultaneously 

plotted on the y-axis, including multiple properties from a single hydration 

simulation, or a comparison of the same properties for different hydration 

simulations. To create a plot, first select a hydration operation on the left pull-down 

menu selector (under the heading “Hydration Name”), and then select the desired 

property to plot in the right pull-down menu selector (under the heading 

“Property”). Doing so will immediately create the xy plot in the “Plot result” section.
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The plot is accompanied by a legend indicating both the hydration operation 

and the property, separated by a colon.

Click the “+” button next to the first property in the “Set axes” section to plot a 

second property on the same plot. This will create a second row with the same pull 

down menus repeated. The example shown below plots both the degree of 

hydration and total capillary porosity against time for the same hydration operation. 

Notice that the legend is updated to display the information for each curve in the 

plot.

Note: When plotting multiple properties on the same graph, the properties 

must all have commensurate units. For example, both the degree of hydration and 

the total porosity are dimensionless quantities, so they can be plotted together. 

However, the degree of hydration and isothermal heat release have different units, 

so they cannot be plotted simultaneously. The pull-down menu selectors 

automatically exclude incommensurate properties.

You can also compare properties from different hydration operations to analyze 

differences in the behavior of the two systems. The following example adds to the 

example just given by plotting the degree of hydration for another hydration 

operation. Notice that the second hydration operation, “HydrationOf-ASTMC109-

02” only ran for 24 hours.

Plotted curves can also be removed from the graph by clicking on the “-“ button 

next to the corresponding row in the “Set axes” section.

Note: Under some conditions, the generated plot may not automatically rescale 

its axes in an optimal way. This can be corrected by simply clicking once anywhere 

within the region of the plot itself.

It is also possible to zoom in on a narrow range of the x-axis. To do so, place the 

mouse within the plot field at the beginning x value. Hold the mouse button down 

and drag to the ending x value. Releasing the mouse will automatically generate the 

rescaled plot. Again, to go back to the optimal scaling needed to show all the data, 

just click once within the plot region.
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Finally, a high-resolution plot can be created in separate pop-up window by 

clicking on the “High resolution version” link below the legend. The same zooming 

features apply to the high-resolution plot as for the regular plot.

Note: When a hydration operation is running, its progress can be monitored by 

going to this plotting page. The default plot, which has time on the x-axis, will show 

how much simulation time has been reached, even if the operation has not 

completed.

8.2 Measure Cement/Concrete Properties

Clicking on this subtab opens a page for calculating the linear elastic properties, 

compressive strength, and the effective diffusivity of cement pastes, mortars, or 

concretes that have been hydrated. The desired hydration operation can be chosen 

from the pull-down menu selector. When this is done, a listing of the available 

hydration times for this operation appears under the heading “Properties”.

Recall that, when a hydration operation is requested, you have the option to 

select the time intervals at which to output the partially hydrated 3D 

microstructures. For example, if you chose 72.0 h for this interval, then 
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microstructures were saved at approximately 72 h, 144 h, 216 h, etc. These are the 

same times that now appear in the list on this page, as individually collapsed 

sections, any of which can be expanded by clicking on the small grey triangles next 

to the headings.

When one of these individual sections is expanded, it reveals two buttons, one 

to calculate the elastic properties (effective linear elastic moduli) and one to 

calculate the transport properties (effective diffusivity). Clicking on these buttons 

launches the finite element models that calculate these properties on the digital 

image [Garboczi 1998].

The finite element calculations take significant computational time to complete, 

about 20 minutes to 30 minutes for a typical 100 x 100 x 100 grid. Once the 

calculations begin, the relevant section of this page will display several boxes that 

will eventually contain the results of the calculations. While the calculations are 

ongoing, however, these boxes will display the message “Measuring...”. The data 

that are displayed in these boxes when the calculations are completed is described 

now.
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Elastic Properties Results

There are three text boxes to display the elastic properties results:

• A summary of the effective elastic properties of the cement paste, 

including the bulk modulus, K in GPa, shear modulus, G in GPa, Young’s 

modulus, E in GPa, and Poisson ratio, ν. If the material is a mortar or 

concrete, this box will also display the effective elastic properties of the 

mortar or concrete. These latter properties are calculated with 

Differential Effective Medium Theory (D-EMT) [Garboczi and Berryman 

2001], and include the effective K, G, E, and ν. The D-EMT model takes 

the cement paste elastic properties, aggregate elastic properties, and the 

properties of the ITZ (also gleaned from the finite element calculations 

on the cement paste near the aggregate surface, as described below), as 

well as the volume fractions of the paste, aggregates, and air voids. In 

addition to these properties, a mortar or concrete will also have the 

estimated compressive strength displayed in the box, in MPa, which is 

estimated from the empirical relationship between Young’s Modulus and 

compressive strength described by Neville [Neville 1995].

• The second box shows the relative contribution to the elastic properties 

of each phase in the microstructure. For each phase in turn, the 

following data are provided: (1) the volume fraction of the phase, (2) the 

mean value, over all the voxels of the given phase, of the bulk modulus 
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calculated using the linear elastic relation between the local stress and 

the macroscopically applied strain, (3) the fraction that this value is of 

the total effective bulk modulus of the material; (4) and (5) are the same 

quantities calculated for the shear modulus; (6) and (7) are the same 

quantities calculated for the Young’s modulus.

• The third box contains information about the variation of the elastic 

properties of the cement paste as a function of distance perpendicular to 

the aggregate surface. The data appear in five columns, identified here 

as (1) distance from the aggregate in μm, (2) K for the paste (GPa), (3) G 

for the paste (GPa), (4) E for the paste (GPa), and (5) ν for the paste. 

These data are calculated directly from the finite element model results 

and are used to determine the elastic properties of the ITZ. The ITZ 

properties are determined by averaging these data over thicknes of the 

ITZ, which is approximately equal to the median particle size of the 

starting cement powder [Bentz and Garboczi 1999b].

Transport Properties Results

Calculated transport properties are all displayed in one box, and consist of the 

relative diffusion coefficient in the x, y, and z directions. Here the relative diffusion 

coefficient is defined as the effective diffusion coefficient of mobile solution species 

in the material, divided by the diffusion coefficient of the same species in pure pore 

solution of the same composition. In addition, the average relative diffusion 

coefficient over all three dimensions and the formation factor are displayed in the 

text box. The formation factor is the inverse of the average relative diffusion 

coefficient as defined here.
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Following the value of the formation factor, the text box displays phase-specific 

information similar to that displayed for elastic properties above. . For each phase 

in turn, the following data are provided: (1) the volume fraction of the phase, (2) the 

relative conductivity of the phase, that is, the conductivity of mobile species through 

the phase itself divided by the conductivity of the same species through pure pore 

solution of the same composition; saturated porosity has a relative conductivity of 

1.0 by definition, and solid dense phases have a relative conductivity of 0.0, (3) the 

fraction that this phase contributes to the overall effective conductivity of the 

composite materials in each orthogonal direction.

9 My Operations

The “My Operations” page is the central location for checking the status of a 

user’s operations. This guide has already discussed all of the major operations that 

can be executed in eVCCTL, but now is a good time to list all the types in summary.

Microstructure: Creation of a cement paste microstructure

Aggregate: Creation of a mortar or concrete aggregate packing

Hydration: Simulating the hydration of a cement paste

Elastic-moduli: Calculation of elastic moduli of a cement paste, mortar, or 

concrete

Transport-factor: Calculation of relative diffusion coefficients and formation 

factor

On the “My Operations” page, each operation for a user is listed in one of four 

sections, depending on their status: queued, running, finished, or canceled.

Queued operations

When an operation is requested on one of the eVCCTL pages, it is given an entry 

in the database and is placed in a queue waiting to be run. Some operations will 

leave the queue and begin running almost immediately, but some others, such as 

hydration operations waiting for their microstructure to be created, will remain in 

the queue for some time. While in the queue, a new directory is created to store the 
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results, and an input file is created for the C program that will process the input and 

generate the results. On the “My Operations” page, operations in the queue appear 

in a yellow table at the top of the page, with information about the type of operation 

(see the previously enumerated list for types) and the time of the request displayed.

At the right of the entry is a link to delete the operation from the queue. 

Clicking on the “Delete” link will remove the operation request from the database 

and delete the directory associated with the operation.s

Running operations

While an operation is running, it appears in a green table in this section. The 

name of the operation appears as a link. If the name is clicked, the “My Files” page is 

opened to the operation in question so the user can examine the files that have been 

generated for the operation. See Section 10 for more detail on the “My Files” page. 

In addition to the name, the operation type and the time started are displayed.

At the right of the entry is a link to cancel the operation. Clicking on the 

“Cancel” link will terminate the C program that is running the operation, and the 

operation will be moved to the “Canceled operations” section of the page. The input 

and output files associated with the operation will remain intact.

Finished operations

When the C program responsible for running an operation has finished (either 

successfully or unsuccessfully), the operation is moved from the “Running 

operations” section to this section. It appears as an entry in a blue table. As before, 

the name of the operation appears as a link that redirects the page to the operation’s 

entry in the “My Files” page. In addition to the name, the operation type is 

displayed, as well as the time the operation started and finished.

At the right of each entry is a link to delete the finished operation. Clicking on 

the “Delete” link will remove the operation’s listing from the database. All input and 

output files associated with the operation also will be removed from the computer.

Note: The deletion of an operation cannot be undone, so use this feature with 

caution.
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Canceled operations

If a running operation is canceled, its entry appears in this pink table. In 

eVCCTL, the operation cannot be restarted, but it can be deleted. Clicking on the 

“Delete” link at the right of the entry will remove the operation’s listing from the 

database and will also remove all input and output files associated with the 

operation from the computer. The deletion of a canceled operation cannot be 

undone.

10 My Files

Other than the “Measurements” page, the “My Files” page is the main location 

for viewing the progress and results of an operation. The input and output files 

associated with an operation can be viewed here or optionally exported to the 

computer’s Desktop for further examination.

The “My Files” page has five sections, one for each type of operation (see the 

enumerated list at the beginning of Section 9 for a listing of the operation types). 

Each of these sections displays the name of every operation of that type that is 

recorded in the database, regardless of whether the operation is queued, running, 

finished, or canceled. Deleted operations do not appear.

The name of a given operation is actually the heading of a collapsed field that 

can be expanded by clicking on the small grey triangle next to the operation name. 

Expanding a section reveals a three-column table listing all the input and output 

files associated with the operation, along with a short description of the file contents 

and options for viewing or exporting the file. A link appears at the end of each table 

to export all of the files at once in a single compressed archive to your Desktop or 

Downloads folder.
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10.1 Microstructure Operations

Finished microstructure operations have seven or eight associated files, each of 

which is briefly described here.

Grading: A text file containing the aggregate grading specified when creating a 

mortar or concrete. This entry will not be present for cement pastes. The contents 

of this file, and any other simple text file, can be displayed in a scrolling text box by 

clicking on the “Show” link at the right of the entry. It consists of three columns: (1) 

the common name of the sieve, (2) the sieve opening size (in mm), and (3) the mass 

fraction of aggregate retained in the sieve. The text box can be hidden again by 

clicking on the “Hide” link. Of course, this or any other file on the “My Files” page 

can be exported to the Desktop or Downloads folder by clicking on the “Export” link.
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One-pixel bias numbers: Cement paste microstructures in eVCCTL have a 

resolution of 1 μm, but a large number of cement particles are smaller than this 

minimum feature size. To include these particles in the virtual microstructure, they 

are represented as 1 μm clusters of smaller particles. These clusters should have a 

higher surface area and, consequently, a greater rate of reaction with water than a 

single particle of the same size. The one-pixel bias numbers, calculated from 

knowledge of the cement particle size distribution in the submicrometer range, are 

included in this file as a triplet of numbers, one number on each row, for each phase 

in the initial microstructure. The triplet is formatted as follows:

The first number in the triplet is always 0, for reasons having to do the the 

legacy versions of the software.

The second number in the triplet is the bias value, a decimal number typically 

near 1.0, but which may be significantly greater than 1.0 for fine cements, or slightly 

less than 1.0 for coarse cements.

The third number in the triplet is the integer identification number of the phase. 

Appendix I lists the identification numbers for the phases.

Microstructure image: This file contains a listing of the phase occupying each 

voxel in the 3D virtual microstructure. The file has a five-line header with selfdescriptive entries, followed by the integer phase identification number for each 

voxel in the grid, with one voxel per row. Ordinarily, the text version of this file will 

hold little interest to the user. Therefore, clicking on the “Show” link will cause a 

thumbnail color image of a 2D slice from the microstructure to display. Please refer 

to Section 10.2 for more information on working with these images.

Input to genmic: This is the input file read by the C program (genmic) that 

creates the virtual microstructure. It is difficult to read because it is not annotated 

in any way. More sense can be made of the input file by viewing it in conjunction 

with the output file, the latter which provides a running commentary on the types of 

input being read.

Output from genmic: This is the output file produced by the C program 

(genmic) as it runs, especially describing the nature of the input values that are 

read. Note: Ordinarily, the output file will be of little interest, but it can provide 

important clues to the cause of any failure of the program to execute properly. If 

genmic fails for some reason, an error message will typically appear near the end 

of the output file.

Particle SH coefficients: A listing of the coefficients in the spherical harmonic 

(SH) expansion describing the shape of each particle in the microstructure. This file 

probably is of no interest to users of eVCCTL.

Particle image file: This file is a complement to the microstructure image file. 

Whereas the microstructure image associates a unique phase identification number 

to each voxel, the particle image file associates a particle number to each voxel. 

Specifically, a voxel is assigned a number n if the phase at that voxel belongs to the 

nth particle in the microstructure. Porosity is assigned the number zero, and 

particles comprised of only one voxel also are assigned zero. This file is used 
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internally by the C program responsible for hydration operations (disrealnew) 

and should hold no interest for users of eVCCTL.

Cement phase statistics: A tabular display of the number of voxels assigned to 

each phase in the final microstructure, along with the corresponding mass fraction, 

volume fraction, and surface area fraction of that phase in the virtual 

microstructure. This file consists of two sections. The first eight lines of the file 

display the phase statistics on a total clinker solid basis. This section can be used to 

determine how closely the final microstructure reproduces the clinker phase 

fractions and w/b ratio that were requested when the operation was launched. The 

remaining part of the file lists four values for each phase

• The number of voxels assigned to that phase

• The number of voxel faces of that phase that are adjacent to porosity; this is 

the digitized analog of the surface area.

• The volume fraction of the phase in the microstructure, on a total volume basis 

(solids plus porosity)

• The mass fraction of the phase in the microstructure, on a total mass basis 

(solids plus porosity) 

10.2 Displaying Microstructure Images

As already described, microstructure images are displayed as color 2D slices of 

the 3D microstructure. eVCCTL provides the ability to view the microstructure at 

different magnifications and from different perspectives, so we now devote 

attention to explaining these features.

Clicking on the “Show” link for any microstructure image file displays a 

thumbnail image of a 2D cross section from the 3D virtual microstructure. Note that 

it may take several seconds for this image to display because it is being created at 

the time of the “Show” request.

The thumbnail is a color image, with each color corresponding to a different 

phase in the mix. A red vertical stripe through the center of the image represents a 

flat “slab” of aggregate, which is necessary for simulating the packing effects in the 

ITZ, as mentioned in an earlier section. The aggregate slab will be present only if 

coarse or fine aggregate was requested in the mix.

Once the thumbnail is displayed, it can be clicked with the mouse to open 

another page for more detailed examination and manipulation of the image.
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Plane to view: Choose one of three orthogonal directions from which to 

view the microstructure. The viewing planes are defined by the two Cartesian 

coordinate axes they contain (e.g., the yz plane is the plane observed when viewing 

along the x-axis).

Slice to view: Changing this value enables the user to view the image at 

different locations along the axis of viewing. Valid values are in the interval [0,Lx-1], 

where Lx is the number of voxels in the direction being viewed. Values outside the 

valid interval are converted to the nearest value in the valid interval. For example, a 

slice value of -7 would be converted to 0.

Magnification: A positive integer value of M displays the image with M x M 

image pixels corresponding to each voxel in the microstructure. Note: the 

magnification value must be a positive integer. A non-integer value will throw an 

error. 

Once the viewing options are selected, click on the “Get image” button or just 

press the Enter key on the keyboard to view the new image. Images previously 

viewed while this page has been open can be accessed by clicking the “Back” button 

on your browser. Continued clicking of the browser’s “Back” button will return to 

the “My Files” page.

Underneath the displayed image is a key showing the colors assigned to each 

phase in the microstructure. The color key is quite similar to that used to view 

cements on the “Lab Materials” page, described in Section 6.1.
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10.3 Aggregate Operations

Finished aggregate packing operations have seven associated files, each of 

which is briefly described here.

Input to genaggpack: This is the input file read by the C program 

(genaggpack) that creates the virtual microstructure. It is difficult to read 

because it is not annotated in any way. More sense can be made of the input file by 

viewing it in conjunction with the output file, the latter which provides a running 

commentary on the types of input being read.

Output from genaggpack: This is the output file produced by the C program 

(genaggpack) as it runs, especially describing the nature of the input values that 

are read. Note: Ordinarily, the output file will be of little interest, but it can provide 

important clues to the cause of any failure of the program to execute properly. If 

genaggpack fails for some reason, an error message will typically appear near the 

end of the output file.

Microstructure image: This file contains a listing of the phase occupying each 

voxel in the 3D virtual microstructure. In contrast to cement paste microstructures, 

an aggregate packing has either two or three phases present. Porosity and 

aggregate are always present. In addition, if the resolution of the packing is 

sufficiently fine that the ITZ can be resolved, it will appear as a separate phase for 

easy visualization. Clicking on the “Show” link will cause a thumbnail color image of 

a 2D slice from the microstructure to display. Please refer to Section 10.2 for more 

information on working with these images.

Particle SH coefficients: A listing of the coefficients in the spherical harmonic 

(SH) expansion describing the shape of each particle in the packing. This file is of no 

immediate interest to users of eVCCTL.

Phase statistics: A tabular display of the number of voxels assigned to each 

phase in the final packing. There is one line for porosity, one line for aggregate, and 
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one line for ITZ. A value of zero for ITZ does not mean that there is no ITZ in the 

mortar or concrete, but instead means that the virtual packing was created at too 

coarse a resolution to include the ITZ in the image.

Besides these five files, a “oneimage.input” file and a “oneimage.output” file are 

also present in the table. These are used in the auxiliary program to render the 

aggregate packing image, and are of no interest to eVCCTL users. 

10.4 Hydration Operations

Finished hydration operations often have a dozen or more associated files.

Cement alkali characteristics: Contains information on both the total and the 

readily-soluble potassium and sodium in the cement. The format and viewing of 

this file were discussed in Section 6.1.

Fly ash alkali characteristics: This file is required even if the material does 

not contain any fly ash. Its format is identical to that for the cement alkali 

characteristics file.

Hydration image: There will likely be 10 or more of this type of file in the list. 

Each one is a saved 3D microstructure at a different time during hydration. The 

actual number of this type of file depends on the time interval that was specified 

between successive outputs and on the total simulated time. For example, if a user 

requests hydration for 28 d (672 h) with microstructure output every 72 h, there 

will be 10 hydration images (72 h, 144 h, 216 h, 288 h, 360 h, 432 h, 504 h, 576 h, 

648 h, and a final microstructure at 672 h when the run finishes). All but the final 

hydration image files has the following pattern for its name

MicrostructureName.img.xxx.xxh.TT.0yz

where

• MicrostructureName is the name given to the initial microstructure 

(i.e. the microstructure operation name)

• xxx.xxh is the number of hours (to the nearest 0.01 h) of hydration to 

which this image corresponds. Note: The exact time at which the 

microstructure is output is as close to the desired time interval as 

possible, but the elapsed time of each hydration cycle is not constant and 

so output at the exact time interval requested is rarely possible.

• TT is the initial temperature used for the hydration operation, in degrees 

Celsius

• y is 0 if isothermal conditions were specified, or is 1 if adiabatic or semiadiabatic conditions were specified

• z is 0 if hydrating under saturated conditions, or is 1 if hydrating under 

sealed conditions.
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As an example, a hydrated image name of MyMic.img.289.20h.25.001

means the original microstructure is named MyMic.img, the microstructure was 

output at 289.20 h of hydration time, the initial temperature was 25  ̊C, and 

isothermal and saturated conditions were used.

The exception to this naming pattern is the final image that is written when the 

hydration operation terminates. This final image has the pattern

HydrationName.img.TT.0yz

where

• HydrationName is the name given to the hydration operation when it 

was launched. It should be the same as the heading for the table

• TT is the initial temperature used for the hydration operation, in degrees 

Celsius

• y is 0 if isothermal conditions were specified, or is 1 if adiabatic or semiadiabatic conditions were specified

• z is 0 if hydrating under saturated conditions, or is 1 if hydrating under 

sealed conditions.
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For any of the hydration images, clicking on the “Show” link will cause a 

thumbnail color image of a 2D slice from the microstructure to display. Please refer 

to Section 10.2 for more information on working with these images.

Input to disrealnew: This is the input file read by the C program 

(disrealnew) that performs the virtual hydration operation. It is difficult to read 

because it is not annotated in any way. More sense can be made of the input file by 

viewing it in conjunction with the output file, the latter which provides a running 

commentary on the types of input being read.

Output from disrealnew: This is the output file produced by the C program 

(disrealnew) as it runs, especially describing the nature of the input values that 

are read. Note: Ordinarily, the output file will be of little interest, but it can provide 

important clues to the cause of any failure of the program to execute properly. If 

disrealnew fails for some reason, an error message will typically appear near the 

end of the output file.

Image_index.txt: This is a two-column text file. The left column gives the times 

at which the hydration images were output, and the right column contains the full 

path name to the hydration image in question. Ordinarily, this file will be of no 

interest to the user, because any or all the images can be exported to the Desktop or 

Downloads folder by clicking on the “Export” link. 

Parameters file: A listing of the several dozen parameters used by the C 

program (disrealnew) in its execution. These parameters cannot be modified by the 

user.

Slag characteristics: Contains information the physical and chemical 

characteristics of the slag, and the slag hydration products, used in the 

microstructure. This file must be input to the hydration operation even if no slag is 

present in the microstructure. The format and viewing of this file were discussed in 

Section 6.2.

Hydration Results: A large tabular display of the values of the 61 hydration 

properties at each computational cycle. This file has 63 columns and several 

hundred rows, making it difficult to view in the small text box that is provided when 

the “Show” button is clicked. It is much more convenient to Export the file to the 

Desktop and then import the table into a spreadsheet application. Also, recall that 

any one or more of the properties in this file can be simultaneously plotted on the 

Measurements page of eVCCTL.

The meaning of each of the 63 columns in the hydration results file is provided 

in Appendix II.

10.5 Mechanical properties operations

Finished mechanical properties operations have five associated files, each of 

which is briefly described here.
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Input to elastic: This is the input file read by the C program (elastic) that 

performs both the finite element calculations of the effective elastic moduli of 

cement paste and, for mortar or concrete, the effective medium theory calculations 

of the effective moduli and compressive strength of the material. This file has only a 

few lines, but it is not easy to understand because it is not annotated. More sense 

can be made of the input file by viewing it in conjunction with the output file, the 

latter which provides a running commentary on the types of input being read.

Output from elastic: This is the output file produced by the C program 

(elastic) as it runs, especially describing the nature of the input values that are 

read. Note: Ordinarily, the output file will be of little interest, but it can provide 

important clues to the cause of any failure of the program to execute properly. If 

elastic fails for some reason, an error message will typically appear near the end 

of the output file.

Effective moduli results: This file is displayed in the first text box on the 

Measurements page when a mechanical property operation is finished. Its format is 

described in Section 8.2.

Phase contributions: This file is displayed in the second text box on the 

Measurements page when a mechanical property operation is finished. Its format is 

described in Section 8.2.

ITZ elastic characteristics: This file is present only if aggregate has been 

included in the mix (i.e., only for a mortar or concrete). It is displayed in the third 

text box on the Measurements page when a mechanical property operation is 

finished. Its format is described in Section 8.2.

10.6 Transport properties operations

Finished transport properties operations have four associated files, each of 

which is briefly described here.

Input to dc3d: This is the input file read by the C program (dc3d) that 

performs both the finite difference calculations of the effective relative diffusion 

coefficients and formation factor of the given microstructure image. This file has 
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only a few lines, but it is not easy to understand because it is not annotated. More 

sense can be made of the input file by viewing it in conjunction with the output file, 

the latter which provides a running commentary on the types of input being read.

Output from dc3d: This is the output file produced by the C program (dc3d) 

as it runs, especially describing the nature of the input values that are read. Note: 

Ordinarily, the output file will be of little interest, but it can provide important clues 

to the cause of any failure of the program to execute properly. If dc3d fails for some 

reason, an error message will typically appear near the end of the output file.

Major transport output data: This file contains rather verbose output from 

the dc3d program, including the status of the conjugate gradient relaxation method 

[Garboczi 1998] at the end of each iteration. Ordinarily, this file will hold no interest 

for the user.

Transport factor results: This file is displayed in the text box on the 

Measurements page when a transport property operation is finished. Its format is 

described in Section 8.2.

11 Logout

To gracefully log out of the eVCCTL system, click on the “Logout” tab in the main 

menu bar. This logs you out immediately and also takes you to the original login 

page for the system, where you can switch to a new user.

Note: If you wish to shut down eVCCTL and close the browser, as explained in 

Section 3.1, you must also

• Wait for all running operations to finish, or cancel all running operations

• Close the web browser

• Open the Java console window and press Ctrl-C. After a brief pause, you will 

be asked, “Terminate batch job (Y/N)?”. Type “y” and press the Enter 

button. The Java console window will close.
Appendix I: Phase Identification Numbers

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12 Appendix I

This appendix gives the integer identification number and the short display 

name that is used in eVCCTL for each phase that is recognized in the system.

Phase Name Display Name ID

Saturated porosity POROSITY 0

C3S (alite) C3S 1

C2S (belite) C2S 2

C3A (cubic tricalcium aluminate) C3A 3

C4AF (tetracalcium aluminoferrite) C4AF 4

K2SO4 (arcanite) K2SO4 5

Na2SO4 (thenardite) NA2SO4 6

CaSO4∙2 H2O (gypsum) GYPSUM 7

CaSO4∙0.5 H2O (hemihydrate or bassanite) HEMIHYD 8

CaSO4 (anhydrite) ANHYDRITE 9

Silica fume SFUME 10

Inert filler material INERT 11

Slag SLAG 12

Aggregate INERTAGG 13

Aluminosilicate glass (in fly ash) ASG 14

Calcium aluminosilicate glass (in fly ash) CAS2 15

Amorphous silica (SiO2 in fly ash) AMSIL 16

C3A (in fly ash) FAC3A 17

CH (calcium hydroxide or portlandite) CH 19

C-S-H gel CSH 20

C3AH6 (hydrogarnet) C3AH6 21

AFt (generic ettringite) ETTR 22

AFt formed from C4AF dissolution ETTRC4AF 23

AFm (generic monosulfate) AFM 24

FH3 FH3 25

C-S-H formed from pozzolanic reactions POZZCSH 26

C-S-H formed from slag reactions SLAGCSH 27

CaCl2 CACL2 28

C3A∙CaCl2∙10 H2O (Friedel’s salt) FRIEDEL 29

C2ASH8 (strätlingite) STRAT 30

CaSO4∙2 H2O (secondary gypsum) GYPSUMS 31

CaSO4∙2 H2O (absorbed gypsum; not used) ABSGYPSUM 32
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Phase Name Display Name ID

CaCO3 (calcite or aragonite or limestone) CACO3 33

Calcium monocarboaluminate AFMC 34

Mg(OH)2 (brucite) BRUCITE 35

MgSO4 MS 36

CaO (free lime) FREELIME 37

C3A-o (orthorhombic C3A) OC3A 38

Empty porosity resulting from drying (not 

used)

DRIEDP 53

Empty porosity from self-desiccation EMPTYP 55

Saturated porosity in a microcrack (not used) CRACKP 56
AppendixII: Hydration Data Files

55

13 Appendix II

This appendix provides a brief description of each column in the hydration 

results file (ending in .data; see Section 10.4 for more information)

Column Heading Description

1 Cycle The computational cycle

2 time(h) The hydration time in hours

3 Alpha_mass Degree of hydration on a cement mass basis

4 Alpha_fa_mass Degree of hydration of fly ash on a fly ash mass 

basis

5 Heat(kJ/kg_solid) Heat produced (> 0 for exothermic, kJ/kg of solids)

6 Temperature(C) Temperature of the system in degrees Celsius

7 Gsratio Paste gel-space ratio (see [Taylor 1997[)

8 Wno(g/g) Non-evaporable water content (g water/ g cement), 

on an unignited cement mass basis

9 Wni(g/g) Non-evaporable water content (g water/ g cement), 

on an ignited cement mass 

10 ChemShrink(mL/g) Chemical shrinkage in mL/g of cement

11 pH Estimated pH of the capillary pore solution

12 Conductivity Estimated DC conductivity of the pore solution, in 

S/m

13 [Na+](M) Estimated Na+ concentration in solution, in mol/L

14 [K+](M) Estimated K+ concentration in solution, in mol/L

15 [Ca++](M) Estimated Ca++ concentration in solution, in mol/L

16 [SO4--](M) Estimated SO4-- concentration in solution, in mol/L

17 {K+} Estimated activity of K+ in solution on a molal basis 

(dimensionless)

18 {Ca++} Estimated activity of Ca++ in solution on a molal 

basis (dimensionless)

19 {OH-} Estimated activity of OH- in solution on a molal 

basis (dimensionless)
56

Column Heading Description

20 {SO4--} Estimated activity of SO4-- in solution on a molal 

basis (dimensionless)

21 Vfpore Volume fraction of capillary pores

22 Poreconnx Fraction of capillary pore volume that forms a 

percolated network in the x direction

23 Poreconny Fraction of capillary pore volume that forms a 

percolated network in the y direction

24 Poreconnz Fraction of capillary pore volume that forms a 

percolated network in the z direction

25 Poreconnave Arithmetic mean of the previous three columns

26 Solidconnx Fraction of solids that form a percolated 

network in the x direction

27 Solidconny Fraction of solids that form a percolated 

network in the y direction

28 Solidconnz Fraction of solids that form a percolated 

network in the z direction

29 Solidconnave Arithmetic mean of the previous three columns

30 - 63 Vfxxx Volume fraction of phase xxx on a system 

volume basis, where xxx is the display name of 

the phase given in Appendix I.
Bibliography

57

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[Bentz 2005] D.P. Bentz, “CEMHYD3D: a three-dimensional cement hydration and 

microstructural development modelling package. Version 3.0,” NISTIR 7232, U.S. 

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[Bentz and Conway 2001], D.P. Bentz, J.T. Conway, “Computer modeling of the 

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[Bentz and Feng 2000], D.P. Bentz, X. Feng, C.J. Haecker, P.E. Stutzman, “Analysis of 

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[Bentz and Garboczi 1991] D.P. Bentz, E.J. Garboczi, “Simulation studies of the effects 

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[Bentz and Garboczi 1999] D.P. Bentz, E.J. Garboczi, C.J. Haecker, O.M. Jensen, 

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[Bentz and Garboczi 1999a] D.P. Bentz, E.J. Garboczi, “Effects of cement particle size 

distribution on early age autogenous strains and stresses in cement-based 

materials,” Cem. Concr. Res, 29 (1999) 1663-1671. 

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[Bentz and Garboczi 1999b] D.P. Bentz, E.J. Garboczi, “Computer modelling of the 

interfacial transition zone microstructure and properties,” in: M.G. Alexander, G. 

Arliguie, G. Ballivy, A. Bentur, J. Marchand (Eds.), Engineering and Transport 

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Report No. 20, RILEM Publications, Cachan Cedex, France, 1999, pp. 349-385. 

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[Bentz and Haecker 1999] D.P. Bentz, C.J. Haecker, “An argument for using coarse 

cements in high performance concretes,” Cem. Concr. Res, 29 (1999) 615-618. 

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[Bentz and Jensen 2000] D.P. Bentz, O.M. Jensen, K.K. Hansen, J.F. Olesen, H. Stang, 

C.J. Haecker, “Influence of cement particles size distribution on early age autogenous 

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[Bentz and Stutzman 1994] D.P. Bentz, P.E. Stutzman, “SEM analysis and computer 

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(Eds.), Petrography of Cementitious Materials, American Society for Testing and 

Materials, Philadelphia, PA, 1994, pp. 60-73. http://concrete.nist.gov/monograph, 

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[Bentz and Stutzman 1999] D.P. Bentz, P.E. Stutzman, C.J. Haecker, S. Remond, 

“SEM/X-ray imaging of cement-based materials,” in: H.S. Pietersen, J.A. Larbiz, H.H.A. 

Janssen (Eds.), Proceedings of the 7th Euroseminar on Microscopy Applied to 

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[Bullard and Stutzman 2006] J.W. Bullard, P.E. Stutzman, “Analysis of CCRL 

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[Feng and Garboczi 2004] X. Feng, E.J. Garboczi, D.P. Bentz, P.E. Stutzman, T.O. 

Mason, “Estimation of the degree of hydration of blended cement pastes by a 

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[Garboczi 1998] E.J. Garboczi, “Finite Element and Finite Difference Programs for 

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[Garboczi and Bentz 2001] E.J. Garboczi, D.P. Bentz, “The effect of statistical 

fluctuation, finite size error, and digital resolution on the phase percolation and 

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(2001) 1501-1514. http://concrete.nist.gov/monograph, Part I, Chapter 5, Section 

1.

[Garboczi and Berryman 2001] E.J. Garboczi, J.G. Berryman, “Elastic moduli of a 

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