NIST Special Publication 1173 

Virtual Cement and Concrete 

Testing Laboratory 

Version 9.5 User Guide 

Jeffrey W. Bullard 

Materials and Structural Systems Division 

Engineering Laboratory 

http://dx.doi.org/10.6028/NIST.SP.1173 

May 2014 

U.S. Department of Commerce 

Penny Pritzker, Secretary 

National Institute of Standards and Technology 

Patrick D. Gallagher, Under Secretary of Commerce for Standards and Technology and Director 
 

 

 

 

 

Certain commercial entities, equipment, or materials may be identified in this 

document in order to describe an experimental procedure or concept adequately. 

Such identification is not intended to imply recommendation or endorsement by the 

National Institute of Standards and Technology, nor is it intended to imply that the 

entities, materials, or equipment are necessarily the best available for the purpose. 

National Institute of Standards and Technology Special Publication 1173 

Natl. Inst. Stand. Technol. Spec. Publ. 1173, 60 pages (May 2014) 

http://dx.doi.org/10.6028/NIST.SP.1173 

CODEN: NSPUE2 
Virtual Cement and Concrete Testing Laboratory
 

Version 9.5 User Guide
 

Jeffrey W. Bullard1 

Materials and Structural Systems Division 

National Institute of Standards and Technology 

Gaithersburg, Maryland USA 20899-8615 

This document serves as the user ’s guide for the Virtual Cement and Concrete Testing Laboratory (VCCTL) software, version 9.5. Using the VCCTL software, a user may create 3D microstructures of cement paste made with portland cement 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. 

Keywords: Building technology, cement hydration, computer modeling, concrete testing, microstructure, simulation, virtual laboratory 

1Email: jeffrey.bullard@nist.gov

iii 
Contents 

1 Introduction 1
 

1.1 Disclaimer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
 

1.2 Intent and Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
 

1.3 Notation Conventions . . . . . . . . . . . . . . . . . . . . . . . . 2
 

2 Installation 2
 

2.1 Software Prerequisites . . . . . . . . . . . . . . . . . . . . . . . . 2
 

2.2 Terms of Use Agreement . . . . . . . . . . . . . . . . . . . . . . . 3
 

2.3 Installation Folder . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
 

2.4 Ready to Install . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
 

2.5 Finishing the Installation . . . . . . . . . . . . . . . . . . . . . . . 4
 

3 Launching and Closing a Session 5
 

3.1 Closing VCCTL . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
 

4 Logging On 6
 

5 The Main Page 6
 

5.1 Announcements and Tutorials . . . . . . . . . . . . . . . . . . . . 6
 

5.2 The Menu Bar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
 

6 Lab Materials 8
 

6.1 Cements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
 

6.2 Slags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
 

6.3 Fly Ashes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
 

6.4 Fillers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
 

6.5 Aggregates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
 

7 Mix 16
 

7.1 A Note on the Operating Principles of VCCTL Programs . . . . 16
 

7.2 Prepare Mix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
 

7.3 Hydrate Mix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
 

8 Measurements 26
 

8.1 Plot Hydrated Properties . . . . . . . . . . . . . . . . . . . . . . . 27
 

8.2 Measure Cement/Concrete Properties . . . . . . . . . . . . . . . 29
 

9 My Operations 33
 

9.1 Queued Operations . . . . . . . . . . . . . . . . . . . . . . . . . . 33
 

9.2 Running Operations . . . . . . . . . . . . . . . . . . . . . . . . . 34
 

9.3 Finished Operations . . . . . . . . . . . . . . . . . . . . . . . . . 34
 

9.4 Cancelled Operations . . . . . . . . . . . . . . . . . . . . . . . . . 35
 

iv 
10 My Files 35
 

10.1 Microstructure Files . . . . . . . . . . . . . . . . . . . . . . . . . . 35
 

10.2 Displaying microstructure images . . . . . . . . . . . . . . . . . 38
 

10.3 Aggregate Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
 

10.4 Hydration Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
 

10.5 Mechanical Properties Files . . . . . . . . . . . . . . . . . . . . . 44
 

10.6 Transport Properties Files . . . . . . . . . . . . . . . . . . . . . . 45
 

11 Logout 46
 

Appendix A Preparing and Uploading New Cement Data 47
 

A.1 Getting Ready . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
 

A.2 Running processImageJ . . . . . . . . . . . . . . . . . . . . . . . 48
 

A.3 What To Do Next . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
 

Appendix B Integer ID Numbers of VCCTL Phases 50
 

Appendix C Contents of Hydration Results File 51
 

References 53
 

v 
1 INTRODUCTION 

1 Introduction 

This document provides guidance for using the Virtual Cement and Concrete 

Testing Laboratory software, version 9.5. 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 VCCTL software have been described previously [1,2,15], and a large number of applications of these models 

has been published [3–5,7–9,12,13]. This user guide therefore is mostly focused 

on providing a detailed description of the user interface. 

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 

VCCTL 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 VCCTL and associated computer programs, and accepts no 

responsibility for its use. Users of VCCTL 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 VCCTL is intended for educational use only and is 

intended only to supplement the informed judgment of the user. The software package contains computer models that 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 un1 
2 INSTALLATION 

derstood and considered by the user. VCCTL is intended for use by persons 

competent in the field of cement-based materials and having some familiarity 

with computers. 

1.3 Notation Conventions 

Throughout this guide, the following text conventions will be used: 

•	 italicized text will indicate 

–	 words on a VCCTL window or computer terminal window (for example, the Save button); 

–	 key combinations Ctrl-C to indicate the keyboard combination of 

Control plus C). 

•	 Courier font will be used to indicate 

–	 a file name: mycement.img or disrealnew.exe; 

–	 the location of a folder or file: C:\Users\user\vcctl; 

–	 web addresses: http://oracle.com

•	 Bold text will indicate an important note or warning that the user must 

heed (for example, Never close the command window during a VCCTL 

session). 

•	 All capital letters will be used to denote variables in file names or user 

names for which the user must supply the correct value. For example, 

PATH_TO_VCCTL_INSTALL_DIRECTORY, the user is expected to substitute 

the correct path, such as C:\Users\bullard\Desktop\vcctl. 

2 Installation 

2.1 Software Prerequisites 

The following requirements must be met for successful installation and running of this distribution of VCCTL: 

•	 A personal computer running Microsoft Windows 72 either natively or 

as a virtual machine. Other versions of Windows, such as XP, Vista, or 

Windows 8, may or may not be compatible with VCCTL. 

2Certain 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. 

2 
2 INSTALLATION 

•	 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 or more, are commonly available and 

are recommended for the simultaneous execution of multiple simulations 

without loss of performance. 

•	 Java SE Development Kit (JDK) 7, Update 51, or a more recent update. 

Go to http://www.oracle.com/technetwork/java/javase/downloads/

jdk7-downloads-1880260.html to download the latest release of the JDK 

and follow the installation instructions given there. 

•	 Mozilla Firefox, Google Chrome, or Apple Safari web browser. Not required for installation, but Microsoft’s Internet Explorer sometimes produces erratic results when running the software. 

To install VCCTL, drag the vcctl-9.5-installer-windows.exe icon to the Desktop. Once there, double-click on the installation icon. A series of windows will 

guide you through the installation process. 

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 VCCTL 

software. 

2.3 Installation Folder 

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

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

located in your user folder. 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. 

3 
2 INSTALLATION 

2.4 Ready to Install 

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

Next button to 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. Close this box 

by clicking on the Finish button. 

4 
3 LAUNCHING AND CLOSING A SESSION 

3 Launching and Closing a Session 

Before running VCCTL 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 close the browser after it opens. If the installation was successful, VCCTL can be launched from the Desktop 

by double-clicking on the Desktop icon labeled VCCTL 9.5. 

A Java console window will appear on the desktop, with a lot of information scrolling through it: 

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

session of VCCTL. Doing so will cause VCCTL 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 VCCTL. 

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

browser should open to the main login page of VCCTL. Again, if your default 

web browser is Microsoft Internet Explorer, you may observe unexpected or 

erratic behavior in the software. To avoid this, you can either make some other 

web browser your default browser, or you can copy the URL for VCCTL’s login 

page into another web browser. 

3.1 Closing VCCTL 

To properly shut down VCCTL, follow these steps: 

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. 

5 
5 THE MAIN PAGE 

4 Logging On 

VCCTL is a standalone desktop application, but it allows for some 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 enter yourself in the database by clicking on the New User 

link. This link will take you to a 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 (V) as shown. 

Otherwise, a red X (J) 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 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 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 VCCTL application and also features a virtual “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 

6 
5 THE MAIN PAGE 

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. 

5.2 The Menu Bar 

The menu bar is a persistent feature on all pages of the VCCTL 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 VCCTL 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 cancelled) 

•	 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. 

7 
6 LAB MATERIALS 

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

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 as shown below. 

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

relevant material component in the VCCTL database. 

6.1 Cements 

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

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 a 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. a 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 [10, 11]. 

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. 

8 
6 LAB MATERIALS 

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) or by laser 

diffraction from a dilute suspension of cement powder particles in isopropyl 

alcohol. 

New cements can be uploaded into the database in the form of a single 

zipped file archive containing a number of specially formatted files. Details on 

preparing such an archive for upload are provided in Appendix A. 

Cement data 

This section is initially collapsed (hidden) 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. 

PSD: This is a pull-down menu pointing to the file that contains the information on the particle size distribution (PSD) of the cement. This provides a quick 

way to alter the PSD of a cement, but it will only take effect if you press the 

Save or Save As button. An alternative way to modify the PSD of a cement is to 

change the data in that cement’s PSD file. Please refer to the next section, View 

a cement data file, for more information on how to do this. 

9 
6 LAB MATERIALS 

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. This provides a 

quick way to alter the cement’s alkali characteristics, but it will only take effect 

if you press the Save or Save As button. An alternative way to modify the alkali characteristics of a cement is to change the data in that cement’s alkali file. 

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

on how to do this. 

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 (C3S)3 , 

the second row for belite (β-C2S), the third row for total 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 VCCTL software, but are merely present to provide additional information to the user. Changing the data in this box will have no effect 

on a cement’s properties in VCCTL simulations, even if you save the changes. 

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

the autocorrelation function calculated for the combined silicates, C3S, C4AF, 

C3A, Na2SO4, K2SO4, and combined aluminates, respectively. These data are 

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. 

3Where 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 

10 
6 LAB MATERIALS 

Mass fractions of sulfates Three calcium sulfate carriers are recognized: 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. These values may be modified in the 

database by changing them and then pressing the Save button. 

Edit or create 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. 

Several auxiliary data files are used by VCCTL 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. 

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 VCCTL. It describes the physical and chemical properties of both the slag and the slag gel 

hydration product. More information on the meaning of each parameter is 

provided in Section 6.2 on Slags below. 

parameters: There is only one of this kind of file in VCCTL as distributed, but 

users can create others by modifying this one and saving under a different 

11 
6 LAB MATERIALS 

name. 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. Exercise extreme caution 

when modifying the parameter file, and only do so if completely familiar with 

the hydration model. Contact the author for more information about modifying the parameter file. 

chemical shrinkage data: Users can calibrate the time scale for hydration simulations using experimentally determined chemical shrinkage data. This file 

contains the measured data as an example. Users can import other chemical 

shrinkage data by copying and pasting into the box, preserving the format, 

and then saving as a new data file. 

calorimetry data : Users can calibrate the time scale for hydration simulations 

using experimentally determined isothermal calorimetry data. This file contains the measured data as an example. Users can import other calorimetry 

data by copying and pasting into the box, preserving the format, and then saving as a new data file. Users may alter any of the data files and save them by 

pressing the Save or Save As 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. However, the safer and recommended practice is to save the modified 

PSD data as a new file called cement140mod psd, and then use the new file 

to created a modified cement material, thereby preserving all the properties of 

the original cement140 cement. 

6.2 Slags 

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

slag to view, 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. 

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 VCCTL 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. 

12 
6 LAB MATERIALS 

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 database distributed with 

VCCTL), 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. 

Unlike slags, 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). 

The fly ash in the database is set by default to distribute its phases on a particle 

basis. Clicking the other radio button will cause fly ash phases to be distributed 

within each particle pixel-by-pixel. 

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. 

The phase distribution shown is similar to a fly ash that was characterized in 

2004 at NIST [14]. 

13 
6 LAB MATERIALS 

6.4 Fillers 

Inert fillers have only two properties in the current version of VCCTL: specific gravity and particle size distribution. The inventory of fillers in VCCTL 

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 use the cement141 psd file by default to describe their 

particle size distribution. 

6.5 Aggregates 

Coarse and fine aggregates are included in the VCCTL 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 [16]. 

14 
6 LAB MATERIALS 

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) . 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 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). Any of these properties can be changed by the user and 

saved for the given aggregate (Save button) or saved as a different aggregate 

source (Save As button). 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. 

Uploading entirely new aggregate sources, including all the shape data and 

statistics, can be accomplished using the Upload data from a ZIP file field. As 

implied by the name, all the properties of the aggregate must be stored in text 

files with special names, and all the files must be compressed into a single 

ZIP archive to be uploaded correctly. However, the amount of data and the 

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formatting requirements for this feature are extensive, so those interested in 

using this feature are encouraged to contact the author for instructions on how 

to prepare the archive for uploading. 

7 Mix 

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

stored in the VCCTL 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. 

7.1 A Note on the Operating Principles of VCCTL Programs 

An understanding of the underlying operating principles of VCCTL’s microstrucure models will clarify the meaning of some of the parameters and options on 

these pages. VCCTL models are based on a digital-image representation of 3D 

microstructure. That is, 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. 

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 [1, 2]. A discussion of computational tools 

that have been developed to analyze the properties of digital image microstructures can be found in Ref. [18]. Some of the artifacts and limitations of digital 

image approaches are described in Ref. [17]. 

7.2 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 

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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. 

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. 

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 

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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. 

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 that is normally used 

for concrete and also include the value 0.485, the latter of which is used for 

ASTM C109 mortar cube compressive strength specimens. Text fields are also 

available for viewing the mass fractions and volume fractions of solid binder 

and water correponding to the selected w/b ratio. Modifying either a volume 

fraction or a mass fraction will automatically update the other fields. 

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 disabled, are 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 

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

grading (or size distribution). 

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. VCCTL comes with one pre-selected fine aggregate grading that corresponds to the grading specified in the ASTM C 109 mortar cube compressive 

strength test. The coarse aggregate section also comes with a default aggregate 

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

Note: The aggregate grading specified manually by the user can be saved 

in the database for easy retrieval in subsequent mixes. 

Specifying simulation parameters 

After the mix proportions are specified, the user may optionally select or modify any of several simulation parameters. 

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 

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

number generator used in the VCCTL programs require an initial value, called 

a “seed” 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 any integer other 

than zero in the text box; a value of zero will cause VCCTL to automatically 

generate a non-zero pseudo-random integer as the seed. 

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7 MIX 

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 [20]. Realistic cement particle shapes will be placed in the 

microstructure by marking the check box and selecting the shape set from the 

pull-down menu selector. Note that requesting realistic particle shapes will 

require significantly more time to create the microstructure, sometimes two 

or three times as long. If the real particle shape checkbox is not selected, all 

the cement particles will all be digitized spheres. Even if real particle shapes 

are requested, fly ash particles will remain spherical to be consistent with their 

usual morphology. 

Flocculation: Choosing this option will cause the particles placed in the box to 

be displaced in random directions, locking with any other particles with which 

they come in contact during the process. The degree of flocculation is the fraction of particles that you wish to have connected into a single agglomerate. 

A value of 0.0 will cause no flocculation, whereas a value of 1.0 will ensure 

that every particle in the system is attached to a single agglomerated structure. 

Intermediate values between 0 and 1 will cause a number of disconnected agglomerates to form, with the number of agglomerates decreasing, and their 

average size increasing, as the degree of flocculation approaches 1.0. 

Dispersion: Checking this box will ensure that every particle is separated from 

every other particle in the system by a distance of one or two voxels, thereby 

simulating the influence of a strong dispersing agent. 

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 ?m 

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 (Ncp) in the grid, 

which can be calculated according to the equation 

Ncp = Nx Ny Nz 

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7 MIX 

where Nx, Ny, and Nz 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 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 force the creation of an 

aggregate packing, check the next to Create the 3D aggregate packing. 

Note: Creating a virtual aggregate packing often requires 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 (Nap) in the aggregate packing, which can be calculated 

according to the equation 

Lx Ly Lz Nap = λ3 

where Lx, Ly, and Lz are the linear dimensions of the grid in mm, and λ is the 

resolution in mm/voxel. 

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

boundary plane, parallel to the yz-plane, is inserted in the middle of the microstructure, regardless of whether or not an aggregate packing is requested. 

The plane cannot be seen, but cement particles are forbidden to intersect it, 

a condition that simulates interfacial transition zone (ITZ) in mortar and concrete arising from the packing limitations of cement particles near an aggregate 

surface. The properties of the ITZ are important in determining the mechanical 

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properties and transport properties of mortar and concrete [6], 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. 

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 (V) next to the name indicates that it is valid. 

A red X (J) 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. 

7.3 Hydrate Mix 

The NIST cement hydration model [1, 2] operates directly on 3D digital images of cement particle 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. You may 

also specify the apparent activation energies of the three major net hydration 

processes that can occur, which are (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). 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. 

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Thermal conditions 

The thermal condition of the hydrating material may be (1) isothermal, (2) semiadiabatic, or (3) adiabatic. 

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 0.0, which is the adiabatic condition). 

If the material being hydrated is a mortar or concrete, a section will be 

present to specify the aggregate’s initial temperature and its heat transfer coefficient with the binder. This feature can be useful to simulate the influence of 

chilled aggregate on a hot day. However, the feature has no effect if isothermal 

conditions are chosen. 

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. 

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Hydration time 

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. The NIST hydration 

model proceeds in repeated cycles, each of which has a dissolution step, a 

diffusion step to transport dissolved components through the solution, and 

a reaction step. 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 VCCTL, hydration time (t) in hours is related to the number 

of computational cycles (n), according to the parabolic relation 

2 t = βn

where β is the time conversion factor that must be specified, in units of h/cycle2 . 

The default value of 3.5 × 10−4 works reasonably well for a number of cements 

but is not optimized to any particular cement. To optimize the time conversion 

factor, a calibration of the simulation 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 has been calibrated adequately. 

Note: The choice of time conversion factor has no influence on the calculations other than to dilate or contract the time scale for the simulation. 

Using experimental data to simulate kinetics 

Cement hydration kinetics at early times can be calibrated directly using experimental data as an alternative to the time conversion factor. If the cement 

paste has been characterized by continuous chemical shrinkage measurements 

at any isothermal temperature at or near the desired curing temperature4, the 

user can upload the relevant experimental data in the appropriate format on 

the Lab Materials page, check the appropriate radio button in this section, and 

select the appropriate data file from the pull-down menu. See Section 6.1 for 

further details about importing experimental data. 

4The temperature at which the experimental data were obtained must be isothermal and should 

be within ±20 ◦C of the desired curing temperature, or else VCCTL’s method of using an Arrhenius 

correction to the temperature may become less accurate. 

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If one of these options is chosen, the VCCTL model will track the simulated 

progress of hydration in terms of the simulated chemical shrinkage or the heat 

signature, and will make comparison to the available experimental data to determine elapsed time for any degree of hydration. If the simulation reaches a 

time beyond which the experimental data terminate, the models will attempt a 

quadratic extrapolation to later times. 

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 VCCTL is 

the value of the seed for the random number generator. 

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 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. 

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8 MEASUREMENTS 

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. 

Output hydration movie: If this box is checked, the model will output the microstructural state of a 2D slice at time intervals specified by the user. These 

data are then used to create a movie of the progress of hydration that can be 

viewed on the My Files page. Note that the default time interval of 0.0 h will 

result in no movie being created. See Section 10.2 for more information about 

the available options when viewing images and movies. 

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 V (okay) or a red J (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. 

8 Measurements 

In VCCTL, 63 properties 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 C for 

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8 MEASUREMENTS 

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 property to use for the x-axis 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 plot in the Plot result area. 

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8 MEASUREMENTS 

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 

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8 MEASUREMENTS 

for another hydration operation. Notice that the second hydration operation, 

HydrationOf-ASTMC109-02, only ran for 24 h. 

Plotted curves can 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. 

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. 

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8 MEASUREMENTS 

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, 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 (relative diffusivity and formation factor). 

Clicking on these buttons launches the finite element models that calculate 

these properties on the digital image [15]. 

The finite element calculations take significant computational time to complete, about 20 min to 30 min for a typical 100 × 100 × 100 system. 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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8 MEASUREMENTS 

Elastic properties results 

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

•	 The first box provides 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) [19], 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 [21]. 

•	 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 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. the mean value (defined as in (2)) of the shear modulus 

5. the fraction that this value of shear modulus is of the total effective 

shear modulus 

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8 MEASUREMENTS 

6. the mean value (defined as in (2)) of Young’s modulus 

7. the fraction that this value of Young’s modulus is of the total effective 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 as 

1. distance from the aggregate surface (μm) 

2.	 K for the paste (GPa) 

3.	 G for the paste (GPa) 

4.	 E for the paste (GPa) 

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 thickness of the ITZ, which is approximately equal to the median particle size of the starting cement powder [6]. 

Transport properties results 

Calculated transport properties are 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 having 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. 

Following the value of the formation factor, the text box displays phasespecific information similar to that displayed for elastic properties above. For 

each phase in turn, the following data are provided: 

•	 the volume fraction of the phase 

•	 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 

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9 MY OPERATIONS 

porosity has a relative conductivity of 1.0 by definition, and solid dense 

phases have a relative conductivity of 0.0 

•	 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 VCCTL, 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 cancelled. 

9.1 Queued Operations 

When an operation is requested on one of the VCCTL 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 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. 

33 
9 MY OPERATIONS 

At the right of the entry is a link to delete the operation from the queue. Clicking the Delete link will remove the operation request from the database and 

delete the directory associated with that operation. 

9.2 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 the Cancel 

link will terminate the C program that is running the operation, and the operation will be moved to the Cancelled operations section of the page. The input 

and output files associated with the operation will remain intact, and any data 

generated up to the point of cancellation can be viewed on the My Files page. 

9.3 Finished Operations 

When the C program 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 

the Delete link will delete all input and output files generated by the operation 

and will remove the operation’s listing from the database. 

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

with caution. 

34 
10 MY FILES 

9.4 Cancelled Operations 

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

10.1 Microstructure Files 

Finished microstructure operations have either seven or eight associated files, 

each of which is briefly described here. 

35 
10 MY FILES 

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) 

3. the mass fraction of aggregate retained in the sieve 

The text box can be hidden again by clicking on the Hide link. Again, 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. 

One-pixel bias numbers: Cement paste microstructures in VCCTL 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 with 

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 B 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 

self-descriptive entries, followed by the integer phase identification number 

for each voxel in the grid, with one voxel per row. Ordinarily, the text version 

36 
10 MY FILES 

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. This file ordinarily 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 most users. 

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 internally by the C program responsible for hydration operations 

(disrealnew) and should hold no interest for most users. 

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, in this 

order: 

1. number of voxels assigned to that phase 

2. number of voxel faces of that phase that are adjacent to porosity; this is 

the digitized analog of the surface area. 

3. volume fraction of the phase in the microstructure, on a total volume 

basis (solids plus porosity) 

37 
10 MY FILES 

4. 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. VCCTL 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. 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. 

38 
10 MY FILES 

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 a square 

of M × M image pixels corresponding to each voxel in the original image slice. 

Note: the magnification value must be a positive integer. 

Depth Perception: Selecting yes from the pull-down menu will reveal the microstructure just below the surface of the current slice, much as if the porosity 

were filled with a murky liquid. 

39 
10 MY FILES 

Backscattered Electron Contrast: Selecting yes from the pull-down menu will display a gray-scale image of the microstructure in which the relative brightness 

of each phase corresponds approximately to what would be observed in a 

backscattered electron image of a polished section using a scanning electron 

microscope. 

Once the viewing options are selected, click 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. 

Underneath the displayed image is a key showing the colors assigned to 

each phase in the microstructure. The color key is identical to that used to 

view cements on the Lab Materials page, described in Section 6.1. 

10.3 Aggregate Files 

Finished aggregate packing operations have seven associated files, each of which 

is briefly described here. 

40 
10 MY FILES 

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 interest to most users. 

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 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 VCCTL users. 

10.4 Hydration Files 

Finished hydration operations often have a dozen or more associated files. 

41 
10 MY 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 ten 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 have 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 (◦C). 

•	 y is 0 if isothermal conditions were specified, or is 1 if adiabatic or semiadiabatic conditions were specified. 

42 
10 MY FILES 

•	 z is 0 if hydrating under saturated conditions, or is 1 if hydrating under 

sealed conditions. 

As an example, a hydrated image name of MyMic.img.289.20h.25.000 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 of the hydration operation, and TT, y, and z

have the same meaning as before. 

Clicking the Show link for any of the hydration images 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. 

Hydration movie: A file of this type (with extension .mov) will be present if and 

only if the relevant option was selected when the hydration simulation was 

launched. Clicking the Show link will display a thumbnail animation of the 

progress of hydration of a 2D slice from the microstructure. Clicking on the 

thumbnail will produce a larger image that can be viewed at different magnifications and different viewing speeds. 

Pore size distribution: A file with extension poredist is created with every image file. Clicking on the Show link will display a bar chart representation of 

the capillary pore size distribution of the simulated microstructure, plotted as 

a differential distribution. Unlike images, the thumbnail image cannot be expanded and manipulated. 

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 most users, because any or all the images can be exported to 

the Desktop or Downloads folder by clicking on the Export link. 

43 
10 MY FILES 

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 about 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 63 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 and then import it 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 VCCTL. The meaning of each of the 63 columns in the 

hydration results file is provided in Appendix C. 

10.5 Mechanical Properties Files 

Finished mechanical properties operations have five associated files, each of 

which is briefly described here. 

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. 

44 
10 MY FILES 

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 Files 

Finished transport properties operations have four associated files, each of 

which is briefly described here. 

Phase contributions: This file is displayed in the second text box on the Measurements page when a transport property operation is finished. Its format is 

described in Section 8.2. 

Input to transport: 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 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 transport: 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 

[Garboczi98] at the end of each iteration. Ordinarily, this file will hold no interest for the user. 

45 
11 LOGOUT 

Transport factor results: This file is displayed in the first 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 VCCTL 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 VCCTL and close the browser, as explained 

in Section 3, you must also 

•	 wait for all running operations to finish, or cancel all running operations, 

•	 close the web browser, and then 

•	 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. 

46 
A PREPARING AND UPLOADING NEW CEMENT DATA 

Appendices 

A Preparing and Uploading New Cement Data 

VCCTL comes packaged with an executable file called processImageJ.exe

that can be run from the command line to package the data for a new cement 

into the kinds of data files that ultimately will be needed to create the zipped 

archive needed to upload the cement into VCCTL. This program is designed 

to take just the segmented and indexed image file and create nearly all the files 

necessary to upload a cement into VCCTL 9. The program runs from the command line in an interactive way, prompting the user for responses that it needs 

to create the text files. 

A.1 Getting Ready 

1. Make sure that the processImageJ.exe executable file is somewhere in 

your PATH environment, or else be prepared to type in the full path name 

to it when you want to run it. 

2. You must have ImageMagick installed on your computer. It can be downloaded freely at 

http://www.imagemagick.org/script/binary-releases.php#windows

Just download and run the executable from the website to begin the installation, and choose all the defaults during the installation. 

3. Create a folder and put your segmented, indexed image file in the folder. 

Note: the indexed image file must have the extension .txt. 

4. For the purposes of these instructions, we will call the folder NewCement, 

and we will call the image file NewCementIndexedImage.txt. 

5. Decide the name you want this cement to have in VCCTL. For the purposes of these instructions, we will use the name MyNewCement

6. To make the best use of this program, you should have the following data 

ready when you run it, because the program will prompt you for these 

data. You don’t need to have them, but you will have to go back and 

modify the individual files later if not. 

(a) The spatial resolution of the image, in units of μm/pixel. This is 

important because it sets the scale for all the correlation function 

kernels that will get created. Prior experience indicates that an incorrect scaling will not dramatically affect VCCTL results, but it can 

affect the fidelity with which VCCTL microstructures will mimic the 

real microstructure. 

47 
A PREPARING AND UPLOADING NEW CEMENT DATA 

(b) The mass fraction (not percentage) of gypsum, hemihydrate, and 

anhydrite in the cement, on a total solids basis. 

(c) Na2O % by mass 

(d) K2O % by mass 

(e) Readily soluble Na2O % by mass (less than or equal to total Na2O % 

by mass) 

(f) Readily soluble K2O % by mass (less than or equal to total K2O % 

by mass) 

(g) Percent of total Na2O added as NaOH to mix water (usually zero) 

(h) Percent of total K2O added as NaOH to mix water (usually zero) 

(i) A descriptive name for the cement (several words) 

(j) Several words describing the source of the cement. 

(k) Several words indicating the date when cement was characterized 

(e.g., April 2014) 

(l) Surface area of the cement, in units of m2/kg 

(m) How the surface area was measured (e.g., Blaine, BET, particle size 

distribution) 

(n) Knowledge of the indexing of the image (i.e., which phase is associated with which index in the image file). 

A.2 Running processImageJ 

1. Drag the NewCement folder to your Desktop. 

2. Open a command window. 

3. Type cd Desktop\NewCement. 

4. Type FULL_PATH_TO_VCCTL_FOLDER\bin\processImageJ.exe and press 

Enter, where FULL_PATH_TO_VCCTL_FOLDER is the location of the VCCTL 

install folder 

5. Answer each of the questions in turn, based on the information compiled in the previous section. The necessary files will be created in the 

NewCement directory. 

A.3 What To Do Next 

1. If you have the cement particle size distribution in the acceptable format, 

give it the same root name as all the other newly created files in the 

NewCement folder, using the extension .psd, and place it in the NewCement

directory. The correct format is an ASCII text files with two columns 

separated by either a tab or space: 

48 
A PREPARING AND UPLOADING NEW CEMENT DATA 

(a) The particle diameter in μm units 

(b) The differential mass fraction (not percent) for each size. 

If you don’t have the particle size distribution ready, you can add it later 

within the VCCTL software. 

2. Optionally, if you have quantitative X-ray diffraction data available in 

ASCII text form (format is unimportant, usually some kind of tabular 

format), give it the same root name as all the other newly created files, 

using the extension .xrd, and place it in the NewCement directory with the 

other files. If you don’t have the particle size distribution ready, you can 

add it later within the VCCTL software. 

3. Collect all the newly created files in a single zip archive. 

4. When you’re ready, you can upload this zip file on the Lab Materials page 

of VCCTL. 

5. After the upload has completed, the segmented image may not appear, 

but the other fields on the Lab Materials page should be updated as expected. Make sure to save the cement using the Save As button, and give 

the cement the same name as the root name of all the files created by 

processImageJ. 

6. The image of the cement should also appear the next time you visit the 

page and examine the new cement. 

49 
B INTEGER ID NUMBERS OF VCCTL PHASES 

B Integer ID Numbers of VCCTL Phases 

This appendix gives the integer identification number and the short display 

name that is used in VCCTL 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 form) C3A 3
 

C4AF C4AF 4
 

K2SO4 (arcanite) K2SO4 5
 

Na2SO4 (thenardite) NA2SO4 6
 

Gypsum (CaSO4 · 2H2O) GYPSUM 7
 

Bassanite (CaSO4 · 0.5H2O) HEMIHYD 8
 

Anhydrite (CaSO4) ANHYDRITE 9
 

Silica fume SFUME 10
 

Inert filler 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 AMSIL 16
 

C3A in fly ash FAC3A 17
 

Portlandite (CH) CH 19
 

C–S–H gel CSH 20
 

Hydrogarnet (C3AH6) C3AH6 21
 

AFt (generic ettringite) ETTR 22
 

AFt with Fe substitution ETTRC4AF 23
 

AFm (generic monosulfate) AFM 24
 

Fe(OH)3 FH3 25


C–S–H gel with low Ca/Si POZZCSH 26
 

C–S–H from slag reactions SLAGCSH 27
 

CaCl2 CACL2 28
 

Friedel’s salt (C3A·CaCl2 · 10H2O) FRIEDEL 29
 

Stratlingite (C  ̈ 2ASH8) STRAT 30
 

Secondary gypsum GYPSUMS 31
 

CaCO3 (generic limestone) CACO3 33
 

Calcium monocarboaluminate AFMC 34
 

Brucite (Mg(OH)2) BRUCITE 35
 

MgSO4 MS 36


Free lime (CaO) FREELIME 37
 

C3A (orthorhombic form) OC3A 38
 

Dried porosity DRIEDP 53
 

Self-desiccated porosity EMPTYP 55
 

50 
C CONTENTS OF HYDRATION RESULTS FILE 

C Contents of Hydration Results File 

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 computational cycle 

2 time(h) hydration time (h) 

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 liberated (> 0 for exothermic, kJ/kg 

of solids) 

6 Temperature(C) system temperature (◦C) 

7 Gsratio paste gel-space ratio (see [22]) 

8 Wno(g/g) non-evaporable water (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 (mL/g of cement) 

11 pH estimated pH of the capillary pore solution 

12 Conductivity estimated DC conductivity of the pore 

solution (S/m) 

13 [Na+](M) estimated Na+ in solution (mol/L) 

14 [K+](M) estimated K+ in solution (mol/L) 

15 [Ca++](M) estimated Ca2+ in solution (mol/L) 

16 [SO4--](M) estimated SO2−

4 in solution (mol/L) 

17 {K+} estimated molal activity of K+ in solution 

18 {Ca++} estimated molal activity of Ca2+ in solution 

19 {OH-} estimated molal activity of OH− in solution 

20 {SO4--} estimated molal activity of SO2−

4 in solution 

21 Vfpore Volume fraction of capillary pores 

51 
C CONTENTS OF HYDRATION RESULTS FILE 

Column Heading Description 

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 columns 22–24 

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 columns 26–28 

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. 

52 
REFERENCES 

References 

[1] Dale P. Bentz. Three-dimensional computer simulation of cement hydration and microstructure development. J. Am. Ceram. Soc., 80(1):3–21, 1997. 

1, 7.1, 7.3 

[2] Dale P.	 Bentz. CEMHYD3D: A three-dimensional cement hydration 

and microstructure development modeling package. Version 3.0. NISTIR 7232, U.S. Department of Commerce, June 2005. Available at 

http://ciks.cbt.nist.gov/monograph. 1, 7.1, 7.3 

[3] Dale P. Bentz and J. T. Conway.	 Computer modeling of the replacement 

of ‘coarse’ cement particles by inert fillers in low w/c ratio concretes: Hydration and strength. Cem. Concr. Res., 31:503–506, 2002. 1 

[4] Dale P. Bentz, X. Feng, Claus J. Haecker, and Paul E. Stutzman. Analysis 

of CCRL proficiency cements 135 and 136 using CEMHYD3D. NISTIR 

6545, U.S. Department of Commerce, August 2000. Available online at the 

NIST electronic monograph, http://ciks.cbt.nist.gov/monograph, Part I, 

Chapter 4, Section 3. 1 

[5] Dale P. Bentz and Edward J. Garboczi. Simulation studies of the effects of 

mineral admixtures on the cement paste-aggregate interfacial zone. ACI 

Mater. J., 88:518–529, 1991. 1 

[6] Dale P. Bentz and Edward J. Garboczi.	 Computer modelling of interfacial transition zone microstructure and properties. In M. G. Alexander, 

G. Arliguie, G. Ballivy, A. Bentur, and J. Marchand, editors, Engineering 

and Transport Properties of the Interfacial Transition Zone in Cementitious Composites, pages 349–385. RILEM, Paris, FRANCE, 1999. 7.2, 8.2 

[7] Dale P. Bentz, Edward J. Garboczi, Claus J. Haecker, and Ole M. Jensen. 

Effects of cement particle size distribution on performance properties of 

cement-based materials. Cem. Concr. Res., 29(10):1663–1671, 1999. 1 

[8] Dale P. Bentz and Claus J. Haecker. An argument for using coarse cements 

in high performance concretes. Cem. Concr. Res., 29:615–618, 1999. 1 

[9] Dale P. Bentz, Ole M. Jensen, K. K. Hansen, J. F. Olesen, H. Stang, and 

Claus J. Haecker. Influence of cement particle size distribution on early 

age autogenous strains and stresses in cement-based materials. J. Am. 

Ceram. Soc., 84(1):129–135, 2000. 1 

[10] Dale P. Bentz and Paul E. Stutzman.	 SEM analysis and computer modelling of hydration of Portland cement particles. In S. M. DeHayes and 

D. Stark, editors, Petrography of Cementitious Materials, pages 60–73. American Society for Testing and Materials, Philadelphia, PA, 1994. 6.1 

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[11] Dale P.	 Bentz, Paul E. Stutzman, Claus J. Haecker, and S. Remond. 

SEM/X-ray imaging of cement-based materials. In H. S. Pietersen, J. A. 

Larbia, and H. H. A. Janssen, editors, Proceedings of the 7th Euroseminar on 

Microscopy Applied to building Materials, pages 457–466. Delft University of 

Technology, 1999. 6.1 

[12] Jeffrey W. Bullard and Edward J. Garboczi. A model investigation of the 

influence of particle shape on portland cement hydration. Cem. Concr. Res., 

36(6):1007–1015, 2006. 1 

[13] Jeffrey W. Bullard and Paul E. Stutzman. Analysis of CCRL Portland cement proficiency samples number 151 and number 152 using the virtual 

cement and concrete reference laboratory. Cem. Concr. Res., 36:1548–1555, 

2006. 1 

[14] X. Feng, Edward J. Garboczi, Dale P.	 Bentz, Paul E. Stutzman, and 

Thomas O. Mason. Estimation of the degree of hydration of blended cement pastes by a scanning electron microscope point-counting procedure. 

Cem. Concr. Res., 34(10):1787–1793, 2004. 6.3 

[15] Edward J. Garboczi.	 Finite element and finite difference programs for 

computing the linear electric and elastic properties of digital images of 

random materials. NISTIR 6269, U.S. Department of Commerce, December 1998. 1, 8.2 

[16] Edward J. Garboczi. Three-dimensional mathematical analysis of particle 

shape using X-ray tomography and spherical harmonics: Application to 

aggregates used in concrete. Cem. Concr. Res., 32(10):1621–1638, 2002. 6.5 

[17] Edward J. Garboczi and Dale P. Bentz. The effect of statistical fluctuation, 

finite size error, and digital resolution on the phase percolation and transport properties of the NIST cement hydration model. Cem. Concr. Res., 

31:1501–1514, 2001. 7.1 

[18] Edward J. Garboczi, Dale P. Bentz, and Nicos S. Martys. Digital images 

and computer modelling. In P-z. Wong, editor, Methods in the Physics of 

Porous Media, number 35 in Experimental methods in the Physical Sciences, pages 1–41. Academic Press, San Diego, CA, 1999. 7.1 

[19] Edward J. Garboczi and James G. Berryman.	 Elastic moduli of a material containing composite inclusions: Effective medium theory and finite 

element computations. Mech. Mater., 3e:455–470, 2001. 8.2 

[20] Edward J. Garboczi and Jeffrey W. Bullard. Shape analysis of a reference 

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[21] A. M. Neville. Properties of Concrete. Prentice-Hall, Harlow, England, 1995. 

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55