NISTIR 6968 

User's Guide to the Virtual Cement 

and Concrete Testing Laboratory 

n ribution 

I I 

J (jlI- bl 3D Patticie 

Microstructure_ 

Version 1.1 

\ 

Jeffrey W. Bullard 

I 

-\ - L 

- tocorrelation 

functions from 

2-D image of 

actual cement 

3-0 cement with 

clinker phases, gypsum, 

and additives / 

b 

. ' Prediction of hydrated ...... 

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.. ..... microstructuti pius .... 

..... .::. .. varlous propertles .... ...... ....... . . ~. ... ... ...... .. 

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thermal condition, 

kinetic coefficients 

. 

. 

. 

Set point 

Degree of hydration 

Chemical shrinkage 

Compressive Strength 

Adiabatic Heat Signature 

Transport Properties 

lntetfacial Transltlon Zone 

.. 

.. ...... 

. . '. 1 .... .. 

.. 

National Inrtituto of Standards and Technology 

Technology Administration, U.S. Departmenl of Commerce 

NTSTIR 6968 

User’s Guide to the Virtual Cement 

and Concrete Testing Laboratory 

Version I. 1 

Jeffrey W. Bullard 

Building and F-ire Research l~ahoruton~ 

;Yalional Institute qf Stcmdard.7 and Technolorn 

March 2003 

(1,s. DEPARTMENI’ OF COMMERCE 

Donald L. Evans, Secretary 

TECI1NOLOC.Y ADMIYISTRATION 

Phillip J. Bond, [!rider Secretary of Commesce for Technology 

Arden L. Rement. .Jr.. Director 

NATIONAI, INSI.ITllTE OF STANDARDS AND TECHIVO1,OGY 

USCT'S Giiiili> tii tlic 

Virtual Cement arid Coricrek Testiiig Laboratory 

Viwiiiii I. 1 

ABSTRAC'T 

... 

111 
Contents 

Abstract ... 111 

List ... of Figures Vlll 

1 Introduction 1 

2 Descriptions of Menu Selections 2 

2.1 Databascs subrrienr~ .................................... 2 

2.2 Birild Microstructure ~itbr~ic:~iii .............................. 3 

2.2.1 Create a PSD fik ................................. 3 

2.2.2 Gcrierat. e initial rriicrost. ructure .......................... 7 

2.23 Dist. rilintc cement. p1i;lsc:s ............................. 11 

2.2.4 Filter to distribrrte only t. wo cerricrit phases ................... 14 

2.2.5 Ailjust. tht: hydrairlic ndius of one phase .................... 16 

2.2.6 Distribirt. t. fly ash phase, s ............................. 17 

2.3 Hydrat. ion srib~ncmi .................................... 20 

23.1 Specify a t.crriperat. urt. sclic~iliilr: (ciiririg) ..................... 20 

2.3.2 Specify slag cliaract. t.ristics ............................ 21 

23.3 Spccifj, alkali charact. eristics ........................... 21 

4 Hydrat. o a :I-D rnicrostrirct. ~rc. .......................... 21 

23.5 Dcsc:riptiori of ont. put file IULIIICS arid t. hcir cvridcrits ............... 29 

2.4 Aridysis sutxncnu ..................................... 30 

2.4.1 Phase st.at. istics .................................. 30 

2.4.2 ITZ characteristics ................................. 32 

2.4.3 Connectivity (F'c~'c~~hti~)ri) ............................. :(2 

2.4.4 Rcsldts of hydration siniuladion .......................... 32 

2.4.5 Rcsults of sulfatr: at.t. ack ............................. 34 

2.4.6 R.osirlts of clast. ic rnodiili (xl(.iiht. ion ....................... 34 

2.4.7 R.csirlts of DC coridiict. ivity calciilat. ion ..................... 34 

" 

.... 
:I Summary 40 

4 Acknowledgnierits 40 

I3 Appendix B 46 
References 

vii 

47 
List of Figures 

I 

2 

:I 

4 

.5 

(i 

.. 

i 

8 

0 

IO 

11 

12 

l:i 

I .1 

I5 

I fi 

I7 

IX 

I9 

20 

'I 

:> 

:j 

:+ 

I 

I 

fi 

X 

X 

!I 

IO 

I' 

I :i 

II 

I 5 

I fi 
22 

23 

24 

25 

26 

27 

28 

2!1 

30 

3 1 

32 

3:3 

34 

3 5 

Bottom port,iori of t,hc socond of fivo forms for laiinc:liing t,hc VCCTL hydr;rt,iori rnodcl. 24 

Top port,ion of tlir: third of fivc forms for lairri(:hirig the VCCTL hydrat,iori modd . . 25 

Plot of (ic:grcc of hydrat,ion (0) vc:rsiis riinribt:r of hydrat,ion cycles for CCRL Ccnicrit 

140 hwing w/i: = 0.40. Cnririg was sinnr1atr:d at 25 "C uridcr satiir;tted coriditions. . 2,5 

Bot,toni portion of t,hc t,hird of fivc forrris for launching t,he VCCTL hydration rnodel. 27 

Fourth of five forms for lainicliirig thr VCCTL hydration niodcl (t,op portion). , . . . 28 

Fifth of fivc forms for laiiricliing tlic VCCTL hydrat,iori ~~iodd. . . . . . . . . , . . . 20 

Thc! Analysis siibnit:mi stktions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . :31 

Pliasc statistics table gc:ncrat,c:d iisirig t,lic Phase statistics sribrri~mi. . . . . . . . . 31 

Evalnat,ion of pt:rc:olat,ion iisirig the Connectivity (Percolation) sirbrrmnii item. . 32 

Pull-down memis t,o sclc 

expcrimr:ntd data. . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . :13 

Top portion of t,ahlc for plott,irig liydr;tt,ion propcrt,ic:s. . . . . . . . . . . . . . . . . . 33 

Display of a 2-D slicc from a :<-D microstrirct,irrt:. . . . . . . . . . . . . . . . . . . . . 35 

Form for mt,r:ring rnixt,iirc: pararn(tc:r dat,a iwed t,o estimate t,hr: c:hlorido-ion diffusion 

coc:fficient of concrete. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 

Examplc: of an oiitgrit, gag(: gcxieratcd when tho chloridr:-ion diffiisiori cocfficiont of 

c:oncrt:t,c is cstimated based OIL niixt,iirr pafimictcrs. . . . . . . . . . . . . . . . . . . . 38 

Form for launching a. sinniht,ion of lcdiirig of onc or niorc phascs froni a cement, 

pastc niicrostrnctiirc. . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . 39 

PSD form for crvating c:xarnplc: crrricrit PSD filo. 43 

F'SD form for creitt,irig exarnplt: finned silica PSD filc. . . . . . . . . . . . . . . . . . . 44 

Valiics for sulfate additions basd on ~xample mix desigri. . . . . . . . . . . . . . . . 44 

a 1iydratc:d systcrri for either plott,ing propr:rtics or cntcring 

. . . . . . . . . . . . . . . . . . . . 

ix 
1 Introdiiction 

DISCLAIMER 

INTENT AND USE 

I 
2 Descriptions of Menu Selections 

Y 

EnwQ H & 

n "'=v.& at w,) - - M 

- E 

- - m 

(ubh.Isw...l. 

-m= 

Figure 1: Main menu for the Vlrtual Cement and Concrete 

Testlng Laboratory 

Upon entering the Virtual Cement and Concrete Testing Laboratory (VCCTL) system, 

the page shown in Figure 1 is displayed. 

The page consists of three frames. The top 

and bottom frames, which are tinted, are 

always displayed and contain links to common websites such as the National Institute 

of Standards and Technology (NIST) home 

page (upper right image). the Building and 

Fire Research Laboratory (BFRL) home 

page (upper left image), and the VCCTL 

main menu (upper middle image). The center frame (with white background) is the 

VCCTL Main Menu. 

The main menu in earlier versions of 

VCCTL was composed of a list of descrip 

tive actions. In Version 1.1, the main menu 

is subdivided into functional submenus, 

e.g.databases, build microstructure, hydration, etc., that reflect the order in which 

users commonly execute actions. Each of 

the submenus are discussed in the following 

subsections. 

2.1 Databases submenu 

Cement database For users of the VCCTL who do not have access to a scanning electron 

microscope (SEM) with X-ray imaging capabilities, a database of cement images has been created. 

With each installation of the software, a core set of fully characterized cements is stored in the 

database. Currently, this database contains 2-D images, quantitative image analysis results, and 

measured particle size distributions (PSDs) for 26 different cements produced in four different 

countries, as shown in Figure 2. The characterization process has been described in detail for 

two of the Cement and Concrete Reference Laboratory (CCRL) cements in a previously published 

report [6]. Typically, the PSD and quantitative phase analysis information will be used as input 

to construct a starting 3-D microstructure for a specific cement (see the Build Microstructure 

submenu section). 

Upon entering the cement images database, the user will first be allowed to select a specific 

cement of interest using a fill-in form. Once this form is submitted, a 2-D color processed SEM/Xray image will be returned along with the measured PSD for the chosen cement, as shown in Figure 3 

for CCRL Cement 141, issued by the Cement and Concrete Reference Laboratory in June 2000. 

Below the image, the differential PSD (not shown in Figure 3) is tabulated on a particle diameter 

basis, in terms of both mass and number fractions. The number fractions have been obtained from 

the mass fractions based on the number of pixel elements present in digitized 3-D particles of each 
. &.. ...... ... I m j DUPY i I.lm 1 1.101 . 

j sn ~ 1.m 0.w 1.m j 4 .. 

._ .................... i i.-. 

Is* 1.7lll i 0.1111 1 DYn .. > ................... ! L 

Figure 2: Portion of the form to select a cement from the cement images database. 

specific diameter [l]. For small diameters (3 pixels and 5 pixels), it should be noted that the volume 

of the digitized sphere is significantly greater than that of a true sphere of equivalent diameter. 

Figure 3: First half of page 

CCRL Cement 141, showing 

Figure 3 also indicates the new color 

coding scheme that has been adopted uniformly throughout VCCTL Version 1.1 software. The new colors mimic the approximate colors of the clinker phases when 

lightly etched with hydrofluoric acid and ob 

served by reflected-light optical microscopy. 

The page displayed for each cement also 

contains a link, About this cement, that directs the user to a second page containing ~ 

the quantitative image analysis results for 

the cement, including the names of the computed correlation files which can be used to 

create “equivalent” 3-D microstructures. 

from cements image database for 

the new color scheme. 

2.2 Build Microstructure submenu 

This submenu includes all of the functions required to create fully three-dimensional microstructures of cement paste that are ready for simulations of hydration. One of the unique aspects of 

the VCCTL models is the level of accuracy with which it constructs microstructures based on information from real cement powders. Aspects of microstructure that are faithfully reproduced by 

VCCTL software include the particle size distribution (PSD) of individual components, the volume 

fraction and surface area fraction of clinker compounds, volume fraction of mineral additions, and 

relative flocculation/dispersion of the cement paste. 

2.2.1 Create a PSD file 

This menu selection is used to create and store a particle size distribution (PSD) file which specifies 

the number of cement particles of each diameter to be placed in a starting 3-D microstructure. The 

3 
output file created by this selection can be specified as input to the next submenu item, Generate 

initial microstructure. 

Entering the Create a PSD file submenu takes the user to a form shown in Figure 4, which 

requires the user to select a cement from the local database. Choosing any cement from the cement 

database will load information about the PSD of that cement, i.e., the mass fraction as a function 

of particle diameter. For each cement, these data are stored in the cement images directory, in a 

subdirectory for that cement name, in a text file having a .psd extension. 

PSD Selection 

uw6 ?hs form 

SdCCt apardclc rhcdlrhibuuolltfm Mlonpthosc.Vanab1e mthcIo~IyltuR or relcctthcdclault PSD. 

Figure 4: Form for selecting a cement PSD, system size, and system resolution, 

Once the user submits this form, a second form is displayed. This form (shown in Figures 5 

and 6) is used to actually specify PSD information, which will be written to a file. The components 

of the form are as follows: 

Ps- - ~ - - snt 

.... 

! 

Figure 5: Top portion of the web form for creating a PSD file. 

4 

Figure 6: Bottom portion of the web form for creating a PSD file 

the mass fraction of these larger diameter particles to zero and repeat the automatic calculation by 

respecifying the desired value. Alternatively, if the intended simulations depend on the influence 

of coarse particles, or if the PSD of the cement is weighted heavily toward larger particles, then 

the user may manually decrease the numbers of smaller particles from several classes until the w/c 

ratio is closer to the desired value. This has limited impact if many large particles are required. 

Total number of pixels The user may request an approxlmate total number of solid pixels (not 

particles), and the embedded Javascript code will automatically calculate the numbers of particles 

of each size that most closely approximate that total. Note that the actual pixel total usually 

will not equal the value requested, because only whole numbers of particles of each size class are 

allowed. 

Specifying the total number of pixels often comes in handy when the user is attempting to 

construct a blended cement from several different materials (e.g., flyash, pozzolans, inert fillers 

etc) If the PSD file for the clinker already has been created by specifying w/c ratio, and if the 

total number of cement pixels is therefore known, then PSD files for a subsequent component can 

be made by calculating the number of pixels of that component needed to achieve the desired 

volume fraction of solid and using that value to create the new PSD. A stepby-step example of 

this procedure for creating a blended cement microstructure is provided in Appendix A. 

Name of the particle file The data in the PSD table will be saved to a file €or subsequent use in 

other calculations. Note that only the file root should be supplied (Le., no file extension should be 

added) because the VCCTL software automatically appends the extension .psd to the name that 

is supplied. The file must have a unique name not already stored in the system; an error message 
2.2.2 Generate initial microstructure 

7 
files rather than manual entry. Manual entry is tedious and prone to typographical errors that may 

go undetected. 

Figure 7; Entry page for creating an initial 3-D microstructure. 

Read particle sizes from files(s) 

and Figure 10 (bottom of the form). 

The form generated is shown in Figure 8 (top of the form) 

Random number seed The user must enter a negative integer, between -32767 and -1, in this 

field. The random number seed is used to initiate the sequence of the C random number generator 

that is used in the program. Random number seeds are requested in a number of web forms, such 

as those for generating the microstructure, distributing clinker phases, and hydration. Choosing 

the same random number seed for two different runs will guarantee the same sequence of random 

numbers that are produced during execution of the program. 

Figure 8: Top portion of the web form for creating an initial 3-D microstructure using pre-existing PSD files. 

Aggregate present The user may choose to place a coarse aggregate particle in the 3-D microstructure. The aggregate particle is modeled as a flat plate of finite thickness. The flat-plate 

approximation is usually satisfactory for most applications because the surfaces of coarse aggre 

gate particles typically have very low curvature compared to cement particles. Aggregate can be 

8 
included to study the formation of the interfacial transition zone (ITZ) microstructure as a function of cement PSD, mineral admixtures, hydration, etc. The default is to exclude aggregate from 

the 3-D microstructure. If selected, the user should also specify the aggregate thickness (an even 

integer) for the flat plate that will be centered in the 3-D microstructure. For further information 

and applications on the use of aggregate slabs in computer modeling of cements, see Refs. 18, 9, 101. 

Flocculation The user may flocculate the cement particles after placing them in the 3-D microstructure. When a superplasticizer or high range water-reducing agent is not used, cement 

particles have a great tendency to flocculate together, perhaps into a single flocculated structure. 

Although this does not have a major effect on the long-term properties of hardened cement paste, 

it does significantly alter the rheological properties and setting behavior of the paste. When flocculation is enabled, the user must specify the numbers of flocs to be present after flocculation. For 

a totally flocculated system, this value would be 1, representing a single final floc (see Figure 9 

for examples). The default behavior is to produce no intentional flocculation, although any given 

particle still might be placed at random in a position of incidental contact with one or more other 

particles. To ensure absence of any interparticle contacts, use the Dispersion option described in 

the next paragraph. For further information, consult Refs. [ll, 12, 131. 

Figure 9: Varying degrees of flocculation among 10 equally sized cement particles. Left to right: no flocs, three 

flocs, and one floc. 

Dispersion distance When a superplasticizer or high range water-reducing agent is used, the 

user may elect to disperse the cement particles to model the action of these specialty chemicals. A 

computational trick is used to place the particles with a radius either 1 or 2 pixels larger than their 

true radius. Since the placed particles cannot overlap, this will assure that all particles placed are 

at least 1 (or 2) pixels separated from all other particles. Note that for w/c ratios below about 0.4, 

this dispersion may not be possible due to the large number of part,icles typically present in the 

microstructure. In this case, the program genpartnew will issue an error message and exit without 

outputting the final microstructures to file. As with flocculation, dispersion does not significantly 

affect the long term properties of the hydrated cement paste, but can drastically alter the rheological 

properties and setting behaviors. For more information, see Refs. [ll, 12, 131. 

NOTE: The user should be aware that the physical distance between dispersed particles will also 

depend on the chosen resolution of the system, since the resolution determines the dimension of 

each pixel. 

Sulfate additions The user has two options for placing calcium sulfate in the microstructure. If 

a separate PSD file for the sulfates is available, the user specifies that file later in the form. The 

form can even accommodate separate PSD files for the different foms of calcium sulfate: dihydrate, 
hemihydrate, and anhydrite. However, if it is assumed that the calcium sulfate and cement have 

the same PSD, the user may just place particles as cement and choose to have a specific volume 

fraction of them randomly assigned as calcium sulfate afterward. In this case, the user must input 

the following in the form: 

the total volume fraction of solids that is some form of calcium sulfate 

the fraction of the total calcium sulfate that shall be hemihydrate 

the fraction of the total calcium sulfate that shall be anhydrite 

ccmmt [- 

Pu?zOlrn 

I 

Figure 10: Bottom portion of the web form for creating an initial 3-D microstructure using preexisting PSD files. 

For example, suppose the system should have 0.02 volume fraction of dihydrate, 0.02 volume fraction 

of hemihydrate, and 0.01 volume fraction of anhydrite. Then the three numbers entered would be 

0.05 (the sum of all three), 0.40, and 0.20, respectively. This will assign 0.05 x 0.40 = 0.02 volume 

fraction of the placed particles as hemihydrate and 0.05 x 0.20 = 0.01 volume fraction of the placed 

particles as anhydrite, randomly located throughout the microstructure, with the remainder (0.02) 

being distributed as the dihydrate form of calcium sulfate. 

Particle size distribution files PSD files, created using the Create a PSD file submenu, may 

be specified for several phases/compounds as shown in Figure 10. The user should note that the 

PSD files themselves contain only the number of particles of each size class to add. If more than 

one PSD file is specified in the form, the numbers for each size class in each file are summed. The 

user bean the responsibility of ensuring that the PSD files were all created in such a way as to 

produce the desired water-tesolids ratio. 
2.2.3 Distribute cement phases 
Clicking tho Distribute cement phases link leads t,o t,llc> page shown in Figure 11. which 

requests two it,(:nis: 

Name of original microstructure file This must, he t,hc namc of i~ 11-D microst,ru(:tlire image 

(cxt,ension . img) that has not had tlic cc:mont phases dist~rilintcid already. i.c., any microstriict,urr: 

image t,liat, was not crcat,ed Iirevioiisly using this form. Typically. this will be a filc crwnt,ed previously 

by using thc: Generate initial microstructure suhrnc~rni (Section 2.2.2). 

Match distribution data using cement: 

will be used t,o match the t,wepoint, correlation functions. 

c,emcnts ditt,abase (see Scction 2.1) shoiild bc avidable for sclcctiori. 

This is tlic: iisme of t,hc charact,crized c,rmcnt tlist, 

All of the ceni(:nt,s recorded in tllc 

Phase Fraction and Distribution Files 

Phe Dblribution Filer 

Sdccrrhrpharc h~mbunonlrornsmong~osc wdablr anrhalocd EY"M, orxJcrtfhc defdtBD Rrr~ 

rheSuboufbuttton fa pcoreed to rhcnexpagc 

deiault AI 

Figure 11: Entry psgc for disi,rihuting r.rmcrrt phases arrarrrgst wrnent particles irr B :3-D niicrostrwtiur, inrage. 

Upon pressing tlic "Submit" hut,ton on t,his page. a sccorid form is displayed. as shown in 

Figure 12 (the topmost portion of this form. which displays an irnagc of the cenient, sckted. is 

omitt,ed from the figiirc). A dcscript,ion (if t,he forrn cntrics is providrd hclow. 

Version 1.0 file detected rgc: appears only if tllc name of t,hc original microst,ruct,ure 

file, entered in the previous form) appears not to have heen crcskd rising VCCTL Version 1.1. 

In this case, Vcrsion 1.1 docs not 1i;ive a scvcral items of information. such as the part,irle 

irnagc file. the nurnticr of one-pixel part,i 

This mc 

used diiriw creat,ion of the original file. 

Whcn a Version 1.0 filc is (if ttd hc~c. the liscr is prornIit,ed for t,hc name of t,hc particle 

image file that was generated during rreat,ion of t,he original filo. Urd t'he iiscr llas irit,entiorlally 

c,hangcd t,he naming convention in sonic way: t,he partick: irriage filc will lvave the sanic name as the 

original rni(:rostruct,urc fih:, ent,ered on the prt:vious form, (:xc,ept that thc character "p" is added 

at, the beginning. This is t,he defwlt name provided in this fidd. \Vit,h a valid psrticle image file 

nunc. and an automatic scan of t,hc origird microst,rnct,llrr filc, t,hr softwasr shoiikl he able to 

convert tlic filc to Version 1.1 format 

NOTE: Vcrsion 1.1 ca~inot det,errninr t,hc numbers and t,ypcs nf one-pixel pinticks that shodd 

he added to microstrilct,ore that, was created using Version 1.0. Therefore. whcn siihmit,ting a 

request, for 1iydr;ition of such a rrii(:rost,rncturc. the user will na(:d t,o calculate t,he numbers and 

t,ypos of onepixcl part,icles using tho online workshcot t,hat, is accessible from t,lit: hydration form 

(ser Sect,ion 2..3.4 for a tlesrription). 

12 
Random number seed The user must ent,er a negative integer (in the range [-32767;-1]) in this 

field. See the description in Section 2.2.2 for more informadion on the purpose of random number 

seeds in VCCTL. 

Filename of original microstructure This must be the name of a 3-D microstructure image 

(extension . img) that has not had t,he cement phases distributed already, i.e., any microstructure 

image that was not created previously using this form. 

Figure 12: Form for distributing cement phasps amongst cement particles in a 3-D microstructure image. 

Filename of the final microstructure Enter the name that you wish the processed microstructurc t,o have after the four major cement clinker phases have been processed. As in previous forms 

already described, only the file root name should be supplied here; the extension . img will be added 

aut,omatically. 

Phase volume and surface fractions The default values shown in these fields are the volume 

fract,ions and surface fractions of each phase already calculated for the cement that was selected 

on the previous form. These data are t,aken directly from the cements database. Therefore, under 

ordinary circumstances they will require no adjustment. The user is free to change the values that 

are shown. However, caution must be exercised t,o ensure that the values of each column sum t,o 

1.0. 

E-mail address Using current, singleprocessor hardware, the program distrib3d that performs 

the distribut,ion of cement phases requires a minimum of 20 min. The actual time to completion 

depends on the speed of the processor as well as the CPU load. The VCCTL will automatically send 

a note to the cmail address provided when execution completes. If no +mail address is supplied; 

then a note will not, be generat,ed. 

12 

f ileroot is the nanie of the cement used in thP cements database 

xxx specifies the phases used t,o create the two-point, correlation function file: 

- sil: silicates (C3S and C2S) are separated from aluminates (C3A and CdAF) 

~ c3s: C3S is separated from C2S (t,his is used after the silicates have been separated from 

aluminates) 

- c3a: C3A is separated from C4AF in cements for which the volume fraction of C3A 

is greater than that of C4AF (this is used aft,er the silicates have been separated from 

aluminates) 

~ c4a: C4AF is separated from C3A in cements for which the volume fract,ion of C4AF 

is greater than that of C3A (this is used afte t,he silicat,es have been separated from 

aluminates) 

Once t,he user selects a correlation function file and presses t,he "Submit" button, a second page 

is displayed as shown in Figure 14 (t,he top portion of this form, which displays an image of the 

cement, is omitted froni t,he figure). The entries in this form are described below. 

Figure 14: Form for distributing two cement phases in a 3-D microstructure image 

Random number seed The user must, enter a negative integer (in the range [-32767>-1]) in this 

field. See the description in Section 2.2.2 for more information on the purpose of random number 

seeds in VCCTL. 

Filename of original microstructure This must be the name of a 3-D microstruct,ure image 

(extension . img) that has not had the cement phases distributed already, i.cI any microst,ruct,rrre 

image that was not, created previously using this form. 

Filename of the new microstructure Enter the name that you wish the processed microstructure to have after this phase separation has been accomplished. As in previous forms already 

described, only the file root name should be supplied here; the extension .img will be added aut@ 

matically. 

15 
Fraction of zm to be maintained as is 

“CdAF”> depending on the file selected in the previous form. 

Here, m can be “silicates”, “CsS”, “C3A”, or 

E-mail address The program rand3d that performs the distribution of cement phases takes less 

time to execute than does the program distrib3d described in the previous section, but the wait 

can still be significant. The VCCTL interface automatically sends a note to the email address 

provided when execution completes. If no email address is supplied, then a note will not be 

generated. 

NOTE: The VCCTL is set up to perform only one of these types of phase distributions at a time. 

Therefore, if the system is busy with one request when another request is submitted, the user will 

be notified to resubmit the second request at a later time. 

2.2.5 Adjust the hydraulic radius of one phase 

Following the filtering process (see Section 2.2.4), the surface area fractions of the filtered phaseswhich can be checked as described in Section 2.4.1- may not match those of the phases in the 

starting 2-D SEM images. These surface area fractions can be adjusted using a 3-D “sintering” 

algorithm to swap specific locations of the two phases in a manner that obtains the desired surface 

area fractions. Details of the 3-D sintering algorithm have been published previously [14, 151, 

with the specific application to cement particles described in the CEMHYD3D Version 2.0 User’s 

Manual [I]. 

Adjust Hydraulic Radius 

Figure 15: Form for adjusting the hydraulic radius of the surfaces of a single phase in a 3-D microstructure image. 

The input form, shown in Figure 15, has the following entries: 

16 

submeriii. The form tllat, apptiars is shown iri Figurc 16 (tog of t,he form) arid Figlire 17 (bot,torri 

of thn forrr1) 

Distribute Phases in Fly Ash 

Randomnumberreed (negativeinteger) lI-3034 

"D~rmbutenyanh pharerrandomlyon aparticle hasis OR 

vDirmbufeflyarh phasesrsndomlyonapiulbasir 

Ini6alduolrmchlrcac: ne"cen '"g 

Pmkle 

(*&enria") 

(Klthextmsion) 

imageae: 

I 

7 

(rYPd?l thz a Wfda wuh ap uifroiunt] 

Number of fly ashpkdc 

Figure 16: Top portion of the form firr distrihiitirrg fly ash phases within "generic? fly ssh particles 

Random number seed Th(: uscr milst, eritw a negative iri,teyw (in the range [-:327G7.-l]) ill t,his 

field. Scc t,he description in Stct,iori 2.2.2 for mor(: iriforniation on t,hc purpose of random nnrnbcr 

se~ls in VCCTL. 

Method for distributing fly ash phases Thc. usw has two choiccss 

1. Particle basis. Each garticlc is assrrrn~:d to tic comprised of a single phaa:. and t,he particles 

are ratidornly assigncd plrases t,o achiwc a closc approxirrration t,o the dcsired phase velum?, 

fractiorm specified iri t,hc t,ablt: at t,hr: bot,torn of t,he form (sc:c Figure 17). Tlic program tllat, 

ext:cut,cs t,his met,hod is callod distf apart 

2. Pixel basis. The pliascs are simply randomly distrihutcrl amongst, a11 the generic fly ash 

pizels to achit:vc t,hc volimie fractions specified in thc table at tht: bott,orn of t,he form (see 

Figire 17). This metliod prodnces a, very fino arid relat,ivcly uniform distribution of the fly 

ash phases within thti individual part,icles. The program that execrit,cs this method is called 

distfarand. 

Initial microstructure file 

. img) t,hat contains gcncric fly as11 particlns. 

This must be t,lic namc of any 3-D rnicrostructiircx irniigc: (cxtension 

Particle image file This IIIIIS~ bc the name of t,lic: particle image filc ;Issociat,cd wit,h t,he micnistruc,ture file alrmdy specified in t,hic previous ent,ry. For mor^ information on t,lic! particle image 

fik:, scc Sect,ion 2.2.2. Because tlir: sanic particle image filc may be associat,ed with any number 

of microst,rircture imqy filcs. this file ~iiirri(~ is r(:qucst,cd separ;rt,ely instcad of being ant,omatically 

const,riictcd from thc iliinic of the rnicrost,riic:tiire image file. 

18 

. .. . 
New microstructure file name Enter the name that you wish the processed microstructure to 

have after this phase separation has been accomplished. As in previous forms already described, 

only the file root name should be supplied here; the extension . img will be added automatically. 

E-dldhs: 

Number of fly ash pixels 

of the microstructure image, as described in Section 2.4.1. 

This number can be determined by computing the spatial statistics 

1 ...... ..... ....... 

Phase fractions Currently, the following phases are considered for distribution amongst the 

fly ash particles: aluminosilicate, calcium aluminodisilicate, silica, anhydrite, calcium chloride, 

tricalcium aluminate, and an inert phase. Reactions between these phases and the main components 

of cement have been incorporated into the current version of the cement hydration model [l, 161. 

A warning message will appear if the user attempts to specify phase fractions the sum of which 

exceeds 1.0. 

Email address On most computers, either program distfarand or distfapart will execute 

within one minute. Nevertheless, the user has the option to specify an e-mail address to which an 

automatically-generated note will be sent upon completion of the calculation. 

Phacebactlonr 

(~WlUbWkk?I8daainsrt): 

ummummj 

bddunl- ! 

I 

................ 

.................................. ................ 

C~Ch!Oridc i 

~MC(CaSO4) ~ 

.. 

silica 

. .- .................... 

............................ .- . 

"I ". .......................................... ....................................... __.., 

TOTAL 

........... 

Figure 17: Bottom portion of the form for distributing fly ash phases within "generic" fly ash particles 
2.3 Hydration submenu 

This submenu provides access to the NIST 3-D cement hydration model. In addition, it also 

provides utilities for creating a curing temperature schedule file, which is required by the hydration 

model under certain conditions. 

2.3.1 Specify a temperature schedule (curing) 

The CEMHYD3D cement hydration model can be executed under one of three thermal conditions: 

isothermal, adiabatic, or user-programmed temperature schedule. ‘This menu selection is used to 

specify a controlled temperature schedule to be used throughout the hydration process. Clicking 

on the submenu entry generates a form shown in Figure 18. If the user is planning to cure under 

isothermal or adiabatic conditions only, then this step can be skipped. 

Temperature schedule file name A name either of a new file or an existing temperature 

schedule file, to which additional data are to be appended, should be entered here. 

Status of file The user may indicate whether the file is (1) created as a new file or (2) opened as 

an existing file for appending the new data. In previous versions of VCCTL, the user was limited 

to six separate temperature ramps or dwell periods. In Version 1.1 the user may append new data 

to an existing file, which effectively removes all constraints on the number of separate entries in a 

temperature schedule. 

Create Tempenture Schedule File 

Figure 18: Form for specifying a programmed temperature schedule for controlled curing. 

20 

I 
2.3.2 Specify slag characteristics 

2.3.4 Hydrate a 3-D microstrncture 

21 
Perform Hydration: Step I 

Need help? 

Ac~~iiih~lattest~~LOn ofmeKll?.ma 

Contermdhelp dromayobtshredby 

d&ngananyenhyhigblightcdlnblur 

NrneoLmi3d~~10Srmc~e c140rc4d 1.g 

Figure 19: First of fivr forms fiir la,mching tlic VCCTL hydration rnoiii4 

t,hc phasc fract,ions and calcrilat,(d nurrihcrs of oiic~-pixd part,i(:h:s from t,hc: partide size distribirtiori 

(PSD). 

Step 2: Othcr 

This form; shown in Figures 20 and 22. appears aft,cr siihniitt,ing t,hc previous form hy prcssirig 

its “Continue” button. It, collcct,s information about the nurnhcr of one-pixcl part,iclcs to place in 

thc rnicrostruct,urc prior to hydrationl and also about t,hrs vohin~e frnct,ion of aggregak if o~it: is 

siInirlating hydrat,ion of t,he cement pask within concrctc?. 

One-PLuel ParUcles 

Access worksheet: 

Phe3eYtoadd Pke ttoam 

c3s: 156518 c2s: j11658 

C3A: CdAE /5636 

Gnrum: 1459 Huruhydratr 10 

Anhydrite: 10 SillcaFumc 

Figure 20: Tup portion of t,hr st:i:ond of five forms for laimching tlir VCCTL hydratiori rmxicl 

Version 1.0 file detected This message appcars only if thc iiainc of tlir! origirml rnicrostrnct,irre 

filc;. cntcrcd in t,he previous form, appears not to have hccn crcated using VCCTL Version 1.1. 

In this case, Version 1.1 does not have access to scvc?ral itcrns of information. such as the part,icle 

image file, t,lie riurnl)er of onr:-pixcl part,iclcs. ctc. iiscd during crcatiori of the original file. 

Wlirri a Versiori 1.0 file is det,ectetl here. the user is pronipt,cd for thc IIHII~C of t,hr particle 

22 
Perform Wdration: Step I 

Microstructure IuformatiQu 

Figure 19: P-irit of tim: forms for laiirv.iiimn the VCCTL hyrliatiori model. 

tlie phasc fractioris arid calciilatcd riiirrii,c:rs of one-pixcl particles horri the pirticlr sizc distrihtioii 

(PSD). 

Figure 20: Top portion of the scud of five formi for laiirirtiing ttic VCCTL hydration rnodrd 

Version 1.0 file detected This rricssagr: appears oiily if the riarile of tlw original riiicrostriicturr~ 

file. eritcrcd iii thc provious form. appears 71wt to havc lieeri (:rcat(>:d iisirig VCCTL Vcliiori 1.1. 

Iri this case. Vcrsion 1.1 docs noi have access io severd itcrris of inforrriation. such as tlir partick. 

irriagc iilt:. tlie riuinbrr of oiic-pixel particles. etc. iised rluririg crriitiori of the original file 

\Vlirri a Version 1.0 file is tlctectrd lierc. tlir nscr is proriiptccl for tiic narric: of the particle 

22 
Perform Hydration: Step I 

Figure 19: First of five forms for launching the VCCTL hydration model 

the phase fractions and calculated numbers of one-pixel particles from the particle size distribution 

(PSD). 

Step 2: Other microstructure information 

This form, shown in Figures 20 and 22, appears after submitting the previous form by pressing 

its “Continue” button. It collects information about the number of onepixel particles to place in 

the microstructure prior to hydration, and also about the volume fraction of aggregate if one is 

simulating hydration of the cement paste within concrete. 

Figure 20: Top portion of the second of five forms for launching the VCCTL hydration model 

Version 1.0 file detected This message appears only if the name of the original microstructure 

file, entered in the previous form, appears not to have been created using VCCTL Version 1.1. 

In this case, Version 1.1 does not have access to several items of information, such as the particle 

image file; the number of one-pixel particles, etc. used during creation of the original file. 

When a Version 1.0 file is detected here, the user is prompted for the name of the particle 

t 
image file that was generated during creation of the original file. Unless the user has intentionally 

changed the naming convention in some way, the particle image file will have the same name as the 

original microstructure file, entered on the previous form, except that the character ”p” is added 

at the beginning. This is the default name provided in this field. With a valid particle image file 

name. and an automatic scan of the original microstructure file, the software should be able to 

convert the file to Version 1.1 format. 

NOTE: Version 1.1 cannot determine the numbers and types of onepixel particles that should be 

added to microstructure that was created using Version 1.0. Therefore, when submitting a request 

for hydration of such a microstructure, the user will need to calculate the numbers and types of 

one-pixel particles using the online worksheet that is accessible from the hydration form [see below 

for description). 

One-pixel particles In previous versions of VCCTL, the determination of the correct number of 

one-pixel particles involved tedious calculation based on the individual PSDs and volume fractions 

of the anhydrous phases. In Version 1.1, however, much of this information is “remembered” and 

automatically uploaded to the form if the microstructure was created in the usual way described 

earlier in this User’s Guide. Therefore, under normal circumstances, the user will not need to 

adjust the values that are displayed on the form. Of course, the user is free to change the values 

at his/her discretion. 

Calculation of numbers of one-pixel particles 

d “a- 

~ . ~ ~ . .... . . . . 

/’ I 

Figure 21: Supplemental worksheet for calculating the numbers of one-pixel particles of each major cement phase 

to be placed prior to hydration. 

If the starting microstructure was created using any VCCTL version prior to 1.1, then the user 

must calculate the numbers of onepixel particles. As an aid in this calculation, a worksheet is 

provided (see Figure 21). The worksheet will calculate the number of onepixel particles of each of 

the four major clinker phases, as well as the various forms of calcium sulfate, based on the current 

number of pixels and targeted volume fractions of each of these phases in the microstructure. The 

current number of pixels of each phase may be obtained as described in Section 2.4.1. This form 

23 
was also available in Version 1.0, but in Version 1.1 it has the additional feature that the data can 

be transferred directly from the completed worksheet to the form by pressing the “Update” button 

on the worksheet. 

Other one-pixel particles Onepixel particles of any phase recognized by the hydration model 

can be added to the microstructure prior to hydration. To add them, the user simply enters the 

phase identification for the desired phase and the number of onepixel particles of that phase that are 

desired (see Figure 22). If the phase identification number of a particular compound is not known, 

clicking on the Phase ID link will display the list of all available phases and their corresponding 

integer identification numbers. Up to two additional phases can be specified in this way. 

Figure 22: Bottom portion of the second of five forms for launching the VCCTL hydration model 

Step 3: Curing and kinetics 

This is the third form in the sequence of five, and appears upon clicking the “Continue” button 

at the bottom of the previous form. The top portion of the form is shown in Figure 23. This 

form collects information about the time of hydration, specifications about the thermal conditions 

and availability of excess water, and data on the average apparent activation energies of the major 

hydration react ions. 

Number of hydration cycles The hydration model operates by a sequence of steps: dissolution 

(in which solid pixels may detach from the solid to become mobile agents in the pore solution), 

random-walker diffusion of the mobile agents, and (possible) reaction between colliding pixels. One 

complete sequence of these steps is called a cycle. Although cement pastes of different composition 

and w/c ratio will produce different results, a typical Type I ordinary Portland cement with w/c 

= 0.40 will often set at -100 cycles (the default value on the form), and the capillary pore space 

will become disconnected at -500 cycles. Furthermore, Figure 24 shows the relationship between 

degree of hydration, (I, and number of cycles for CCRL Cement 140 with w/c = 0.40. 

Terminate when degree of hydration reaches , , . This entry is optional. If the user would 

like the hydration to terminate as soon as a particular value of the degree of hydration (mass basis) 

has been achieved, that value may be entered here. The simulation will terminate when either this 

24 
Figure 23: Top portion of the third of five forms for launching the VCCTL hydration model 

0.8 

0.6 

U 0.4 

0.2 

0.0 

cycles 

Figure 24: Plot of degree of hydration (0) versus number of hydration cycles for CCRL Cement 140 having w/c = 

0.40. Curing was simulated at 25 "C under saturated conditions. 

degree of hydration has been achieved, or when the specified number of hydration cycles hm been 

executed, whichever happens first. By specifying 1.0 (the default value on the form) the simulation 

will execute for the number of cycles specified in the previous entry. 

Time conversion factor Hydration cycles have no intrinsic time scale. In the current version 

of VCCTL, hydration time t is related to the number of cycles n by the empirical relation 

t = fin2 (2) 

where fl is the time conversion factor that is requested in this form entry. fl has units of reciprocal 

time, and typical values for p are =0.0003 h-' (the default value on the form) for a normal Type 

I Portland cement, and =0.0005 h-' for a low-alkali cement. 

It should be noted that the transformation in Eq. (2) is employed not for any fundamental 

reason, but rather because it often provides a reasonable fit to experimental measurements of (Y vs. 

25 
t. A loose physical justification of the parabolic form of Eq. (2) is that diffusion through semipermeable hydration product, which obeys parabolic kinetics, becomes increasingly rate-controlling as 

hydration proceeds. 

Thermal conditions The next several form entries relate to the thermal conditions employed 

throughout curing. The fist one involves choosing the thermal boundary conditions on the system, 

and the options are 

1. Isothermal, for which it is assumed that the system is in diathermal contact with a constantemperature reservoir and that heat transfer is sufficiently rapid to ensure that the system 

maintains the same constant temperature as the reservoir. 

2. Adiabatic, for which it is assumed that the system is thermally isolated from its surroundings. 

3. Temperature-defined, for which a pre-programmed temperature schedule is assumed to 

control the temperature of the system. See Section 2.3.1 for information on creating a temperature schedule for use with this option. 

Temperature schedule file A valid temperature schedule file must be entered in this field 

only if the user chooses to use “temperature-defined” thermal conditions in the previous selection. 

Under isothermal or adiabatic/semi-adiabatic conditions, this field will not be used whether or not 

it contains a valid file name. 

Initial temperature The initial temperature is the starting temperature of the cement paste 

system. If hydration is being executed under a controlled temperature schedule, then the initial 

temperature of the temperature schedule overrides any value entered in this field. 

Saturation conditions The user has two options from which to choose: 

1. saturated, for which the cement paste is assumed to be in contact with a reservoir of excess 

water. As free water in the capillary pore space is consumed by the hydration process, 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. 

2. sealed, for which free water consumed during hydration is not replaced. Instead, the capillary 

pore space is progressively emptied of its water, starting in those pore regions with the largest 

effective diameters. 

The bottom portion of the third form is shown in Figure 25. The form fields in this portion of 

the form relate to apparent activation energies of the main reactions that occur during hydration. 
Figure 25: Bottom portion of the third of five forms for launching the VCCTL hydration model. 

Cement hydration For the present purposes, the process of cement hydration is considered as a 

single composite reaction with a characteristic apparent activation energy which could be measured 

in principle by making an Arrhenius plot of the rate of consumption of anhydrous phases vs. 1/T. 

For a Type I cement, if no further information is available, ASTM C 1074 [17] suggests a value of 

40 kJ/mol. 

Pozzolanic reactions The dissolution of portlandite (CH) due to pozzolanic influence is assumed 

to be a thermally activated process, and the activation energy entered here is used to calculate the 

intrinsic rate of dissolution as a function of temperature according to an Arrhenius expression of 

the form 

where ko is the reaction rate constant extrapolated to temperature T = 0, Ea is the activation 

energy requested here, in units of kJ/mol, and R is the gas constant in units of kJ/(mol.K). 

The activation energy entered here for pozzolanic reactions is also assumed to influence the 

dissolution rate of fly ash phases (ASG and CAS2). The default value is lOOx the magnitude of 

the ideal gas constant, and may be used in the absence of additional information. 

Step 4: Hydration behavior options 

This form, shown in Figure 26, collects information on various aspects of the hydration process 

that have not been addressed previously. 

Conversion of primary C-S-H to pozzolanic C-S-H When silica fume or other pozzolans 

(fly ash, etc.) are present in the starting microstructure, the user may either allow or prohibit the 

conversion of primary C~-S-H hydration product to pozzolanic C-S-H. Pozzolanic CS-H has a 

lower Ca/Si ratio (which causes extra CH to form when the primary C-S-H converts to the pon 

zolanic form) and a different molar volume from that of the primaq C-S-H. The default condition 

is to prohibit the conversion of primary C-S-H. Please refer to the CEMHYD3D User’s Manual [1] 

for more information. 

Precipitation of CH on aggregate surfaces If the microstructure contains an aggregate slab 

(see Section 2.2.2) the user may allow CH to precipitate directly on its surfaces. This will tend 

27 
HydraUon Mor Options 

Figure 26: Fourth of five forms for launching the VCCTL hydration model (top portion) 

to significant,ly increase the CH volume fraction immediately adjacent to the aggregate surf&ce, 

and will consequently decrease the capillary porosity in this region. Because this specific aspect of 

the interfacial transition zone (ITZ) microstructure is still somewhat controversial, the user has the 

option of activating this precipitation or prohibiting it (the default being to allow the precipitation). 

Please consult Refs. [18, 191 for additional information. 

One-pixel particle dissolution bias The probability of dissolution of one-pixel particles, re 

gardless of their phase, can be increased using this parameter. It may be sensible to increase 

the bias if in the initial microstructure there are a substantial number of particles with diameters 

smaller than the system resolution. All such particles are assigned a diameter equal to the system 

resolution, so their higher reactivities will not be captured unless the bias is increased. Allowed 

values are in the range from 1.0 (no bias) to 100. 

Step 5: Data output 

This form, shown in Figure 27, is used to specify how frequently (in cycles) certain properties are 

evaluated and written to data files. 

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

consuming because they involve nested iterations over most or all of the system pixels. Therefore, 

it is recommended that percolation properties not be evaluated every cycle. The default value of 5 

is large enough that performance is not significantly affected and yet low enough that percolation 

thresholds can still be resolved in the data. 

Evaluate percolation of total solids . . . See the discussion in the previous paragraph. 

Evaluate individual particle hydration . . . tion of anhydrous phase reacted for each particle in the microstructure. 

The hydration model can keep track of the frac28 
Figure 27: Fifth of five forms for launching the VCCTL hydration model 

Output hydrating microstructure . . . The exact state of the entire microstructure can be 

saved at regular intervals during the hydration process. Although this can be helpful in preserving 

all the information about the course of microstructure development, keep in mind that each stored 

file requires between 1 and 8 Mb of storage. 

Create movie of hydration . I. A positive integer n entered here will cause a 2-D slice of the 

microstructure to be stored in a file, such that n frames are created by the end of the simulation. 

The hydration model then automatically creates an animated GIF file that can be viewed afterward. 

Consult Section 2.4.10 for details on viewing. 

E-mail address The program disrealnew that performs hydration may take anywhere from 

several minutes to several hours. The actual time to completion depends on the number of cycles 

requested, the speed of the processor, and also depends on the size (total number of pixels) of the 

starting microstructure image. The VCCTL will automatically send a note to the email address 

provided when execution completes. If no email address is supplied, then a note will not be 

generated. 

NOTE: The VCCTL is set up to perform up to two hydration simulations concurrently. Therefore, 

if the system is busy with two concurrent hydration simulations when another request is submitted, 

the user will be notified to resubmit the request at a later time. 

2.3.5 Description of output file names and their contents 

During hydration, several output files are created automatically. 

according to the convention: 

All of these files are named 

f ileroot . 1. . .I . N. TO. abc 

29 
where fileroot is the name of the initial microstructure file without the . img extension, N is the 

total number of hydration cycles, TO is the initial temperature, the remaining flags a, b, and c take 

on the following values: 

0 if C-S-H conversion is prohibited, 

1 if C-S-H conversion is allowed 

a= { 

0 under isothermal conditions, 

2 under temperature-defined conditions, 

0 under saturated curing, 

1 under sealed curing 

b = 1 under adiabatic conditions, 

c= { 

i 

The string [. . .] represents the data that are stored in the file, and may have any of the following 

values 

img 

heat 

adi 

chs 

Pha 

PPS 

PtS 

Ph= 

- 

- 

microstructure image file after the hydration 

degree of hydration (both volume and mass bases), heat released, and gel-space ratio [20], all as a function of time 

system temperature as a function of time 

chemical shrinkage as a function of time 

phase volumes, in pixels, as a function of time 

results for the examination of the percolation of the waterfilled capillary porosity vs. cycles, hydration time, and degree 

of hydration 

results for the examination of the percolation of the total 

solids vs. cycles, computed hydration time, and degree of 

hydration 

results for the hydration degree of individual particles after 

specific numbers of hydration cycles 

- 

- 

- 

- 

- 

- 

When the final hydration form is submitted, all of the user input parameters are echoed back in 

a form, along with the names of all of the output files that may be created by the CEMHYD3D 

program. Normally, however, users don’t need to concern themselves with the contents of these 

files, as they can instead use utilities in the Analysis submenu (see Section 2.4) to plot any 

specific property of interest for the systems that have been hydrated. 

2.4 Analysis submenu 

This menu provides access to utilities for computing various properties of microstructures, for 

viewing images or movies of microstructures, and for viewing the results of various calculations 

that are performed by VCCTL models. The submenu is shown in Figure 28. 

2.4.1 Phase statistics 

This item can be selected to compute the volume pixel counts and surface pixel counts of each 

phase present in any 3-D microstructure. This menu selection can be employed after any step 

30 
MICROSTRUCTURE CHARACTERISTICS 

mPhalcrrltlldcl 

*- 

PLOTTINQ 

0- 

. 

. 

. 

VISUALIZATION 

0- 

. 

.p 

DATA MINMQ 

Figure 28: The Analysis submenu selections. 

during the creation of an initial microstructure, after hydration of an initial microstructure, or 

after degradation/leaching of a hydrated microstructure. To use this selection, the user need only 

supply the name of the 3-D microstructure image file to be analyzed. Within a couple minutes of 

submitting the form, a table of the volume and surface counts, such as that shown in Figure 29, 

will be displayed. Incidentally, compare the values for the clinker compounds in Figure 29 with 

the target values specified for this microstructure in Fig 12. In general, the target values will be 

matched by the distribution program to within 1 O1 &- ., O1. 

Phase Statistics for --JDa.img 

Th1J.nZ10:17~ZW3 

Ph 

ID 

0 

1 

2 

3 

4 

VOh 

caolt 

mu27 

230697 

54750 

271711 

23671 

336m 

21471 

0 

0 

0 

a166 0,6m17 0681112 0.671115 

a55 0,16270 0.11829 0,16474 

3-5 0.08(n7 0,11195 0.07514 

27783 0,07036 0,011164 ODKm 

S4mY 

14559 

0 

0 

0 

Figure 29: Phase statistics table generated using the Phase statistics submenu 

31 
2.4.2 ITZ characteristics 

Given a microstructure with a slab of aggregate included, this selection can be used to analyze the 

phase fractions present as a function of distance from the aggregate surfaces. The user supplies 

the name of the microstructure to be analyzed. A file with with the same root name as the 

microstructure file, but with the extension .agg instead of .img, filename is created. This file 

contains the quantitative phase counts, in pixels, as a function of distance away from the aggregate 

surfaces. All solid phases are examined, in addition to saturated porosity and empty porosity. All 

of the phases and their corresponding integer IDS are tabulated in Appendix B. In addition, if the 

user provides their e-mail address, this same file will be sent to the e-mail address. The data in the 

file then can be further analyzed or plotted using whatever software the user prefers. 

2.4.3 Connectivity (Percolation) 

This submenu item can be selected to evaluate the percolation properties of one or more phases 

in a microstructure image. The user supplies the name of the microstructure file to be evaluated 

and selects the phase(s) from a pull-down menu. In Version 1.1, the percolation properties of the 

following phases can be evaluated: saturated porosity, total porosity, CH, C-S-H, pozzolanic C-SH, total C-S-H, ettringite, or stratlingite. An example of the results for a percolation evaluation 

of saturated porosity in a microstructure, named cemi40wc40a.img, is provided in the table shown 

in Figure 30. For each of the three principal directions (z, y, and z), the VCCTL returns the total 

number of pixels of the phase of interest, the fraction of these pixels which are part of connected 

pathways through the microstructure, and the fraction of the total pixels which are accessible from 

one face of the microstructure. For the example shown in Figure 30, since no hydration has yet 

occurred, the initial water-filled porosity between cement particles is highly percolated, with nearly 

all of the water-filled porosity pixels being part of a percolated pathway. 

Percolation of saturated porosity in csml.(olllcrloa.img 

ThtJmZ13;U:452W3 

Figure 30: Evaluation of percolation using the Connectivity (Percolation) submenu item. 

2.4.4 Results of hydration simulation 

This option is used both to plot the different predicted properties and to enter experimental data 

for comparison against the predicted values. Upon making this selection, a form is displayed with 

two pull-down menus to select a specific system for which either (1) to list the available plots or 

(2) to enter a set of experimental data, as shown in Figure 31. The form is submitted by clicking 

the left button in either row (“List data files for plotting” or ”List data ftles for data entry”). 

32 
Plot Rerub of Hydration 

Figure 31: Pull-down menus to select a hydrated system for either plotting properties or entering experimental data, 

Upon submission of the form, a second form, containing a table of the various options available 

either for plotting or data entry, is displayed (see Figure 32 for an example of a portion the table 

returned in the case of plotting). 

Plot Soledion Fonn 

cpce: cmlIl4~~ 

................................................................. 

;rJ j ;raWbUM. , I 

............................................................ ~ ........................ ~. ..... 

~ 

/ I 

i i !I ! 

~ i 1 

i i ~ 

1 CY- iCwki MA ~ e IT-"/ 

i i i 

i 

i ~ i ~ i 

~ i 

INr*.&..aH ~Hia-mi ~UYI 

I 

i i ~ 

i 

................................... .......................................... 

1 

!.... 

i ~ 1 "mhd jrarmntldI 20 \ 

................................ .................. : .......................... ! ............ ! ................... ..! 

Figure 32: Top portion of table for plotting hydration properties. 

With this table, in the case of plotting, the user can select to create all available plots for a 

given system, or simply to create a single plot of interest. In all cases, the user can elect to include 

the experimental data (when available) on the plot. Typically, the computer model data is plotted 

using blue squares connected by a blue line, while the experimental data is shown as discrete red 

diamond-shaped points. The plot is typically labelled with the name of the datafile from which it 

was created. 

In Version 1.1 of VCCTL, the following plots are available (when the appropriate data have 

been created during a hydration run): 
heat signature: system temperature vs. computed hydration 

time (not very interesting for hydration under 

isothermal conditions) 

chemical shrinkage (ml/g cement) vs. computed hydration time (h) 

degree of hydration (mass basis) vs. computed 

hydration time 

cumulative heat release (kJ/kg cement) vs. 

computed hydration time 

compressive strength estimated compressive strength (MPa) vs. 

computed hydration time. The user must pre 

vide a pre-factor to be used in the calculation 

of compressive strength based on Power’s gelspace ratio theory [20] 

connected capillary porosity vs. either total 

porosity or computed hydration time 

connected “total solids” vs. either computed 

hydration time or degree of hydration 

chemical shrinkage: 

hydration: 

heat release: 

capillary pore percolation: 

solids percolation: 

To enter experimental data corresponding to a specific system, the user has the option of 

(1) downloading the data into the VCCTL from a datafile located on the client computer 

or (2) entering the data manually. In the latter case, the VCCTL will provide a fill-in table 

with two columns corresponding to the values to be plotted on the z-axis and y-axis, respectively. 

For example, to enter data for adiabatic heat signature, the user would have to enter the timetemperature results into this table and then simply submit the form (using the “Copy data” button 

above the data entry table) to store this data file for later access during plotting. Always, when 

experimental data have been entered, the user has the option of including the data file, or omitting 

it, in the associated plot of simulation results. 

2.4.5 Results of sulfate attack 

This feature is currently under development within the Virtual Cement and Concrete Testing 

Laboratory Consortium. 

2.4.6 Results of elastic moduli calculation 

This feature is currently under development within the Virtual Cement and Concrete Testing 

Laboratory Consortium. 

2.4.7 Results of DC conductivity calculation 

This feature is currently under development within the Virtual Cement and Concrete Testing 

Laboratory Consortium. 
2.4.8 View a 2-D slice of a 3-D microstructure 

This selection enables t,he user to graphically examine a 2-D slice from any existing 3-D microstructure (st,artingl hydrated, leached. etc). The user simply supplies the name of the invdge to bc displayed, the z-plane (slice) to select from the 3-D microstructure, and a magnification factor (lx t,o 

lox) for viewing the image. The VCCTL will locat,e the proper slice of the selected image and display a 2-D color image of the microstructure? along wit,h a key identifying the phases corresponding 

to each color. An example is shown in Figure 33. 

Slice 50 from arnl4CwMta.irng200D2.Om 

Q~P1blIll.~:S3mmS 

Figure 33: Display of a 2-D slice from a 3-D microstructure. 

If t,his selection is used repeatedly wit,h the same 3-D image filename, depending on the user's 

Internet browser settings and preferences, the "Reload;' or "Refresh" button on the web browser 

may need to be pressed to update the displayed image to be the currently selected one. In the 

extreme cases where t,his button doesn't load t,he newly generated image, the user will need t,o 

restart their Internet browser or use some other measure to force it to empty the previous image 

from its c,ache. 

2.4.9 

An alternate method of viewing a microst,ructnre is to create a fly-through scan -one z-plane slice 

at, a time--of the 3-D image. This select,ion can be used to create an animated GIF file for a 

user-specified 3-D microst'ruct,ure. For t,his select'ion, the user supplies the following information 

before submitting the displayed form: 

Generate animated scan or hydration movie 

the name of the microstructure to be animated, 

a new filename in which to store the animated GIF file, 

the number of 2-D slices to include in the aninlation (from 1 up to the system size), and 

the magnification (lx~ lox) to use. 
The first slice of the microstructure is always used as the starting slice for the 3-D animation 

generation. Typically, to generate a complete (100 slice) animation of a 3-D microstructure will 

require up to 20 min of CPU time. Therefore, the user should wait at least that long before trying 

to view the animation using the next submenu selection. 

NOTE: The VCCTL is set up to create only one animation at any specific time. Therefore, if the 

system is busy creating one animation when another request is submitted, the user will be notified 

to resubmit the job at a later time. 

2.4.10 View animated scan or hydration movie 

This item is used simply to view the animated GIF files created using the previous submenu item. 

The user need only supply the name of the animated GIF file to be displayed. The animated GIF 

file will be looped five times from start to finish. 

2.4.11 View a data file 

This feature is currently under development within the Virtual Cement and Concrete Testing 

Laboratory Consortium. 

2.5 Transport Properties 

This submenu enables the user to estimate the transport properties (Le., diffusion coefficient of a 

particular ionic species) of a concrete, or to calculate directly the diffusion coefficient of a cement 

paste microstructure that was created, and hydrated and/or degraded using VCCTL models. It 

should be recognized that the diffusion coefficient is a difficult quantity to calculate with accuracy, 

because it depends on complicated aspects of the pore solution composition, in addition to the state 

of the microstructure [21]. A much simpler quantity to calculate, and one which directly reflects 

the iniluence of microstructure on ionic tansport, is the formation factor. 

2.5.1 

This submenu selection is provided to estimate a chlorideion diffusion coefficient for a concrete 

(which may contain silica fume), based on knowledge of its mixture proportions and the degree 

of hydration of the cement binder. The equations used to make the estimate have been presented 

previously [22], are based on a regression performed using published data, and are also incorporated 

into a prototype Computer Integrated Knowledge System (CIKS) for predicting the service life of 

steel-reinforced concrete exposed to chloride ions [23], available separately from the VCCTL. 

Estimate chloride ion diffusivity of a concrete based on mixture parameters 

To use this submenu selection, the user supplies the following four mix parameters for the concrete of interest (see Figure 34): the w/c ratio, the silica fume content (mass % on a cement basis), 

the volume fraction of aggregates, and the degree of hydration of the cement. Recommended 

ranges of applicability for each of these parameters are provided on the fill-in form; 

extrapolations beyond these ranges should be made only with caution. 

36 
Predict Chloride Ion Ditfusiuity in Concrete 

(based on mixture parameters) 

Figure 34: Form for entering mixture parameter data used to estimate the chloride-ion diffusion coe5cient of 

concrete. 

After the form is submitted, the estimated value of the diffusion coefficient, D, (in m2/s) is 

returned along with the 90 '35 confidence limits for D and some recommendations on methods to 

lower the value of D, if desired (see Figure 35 for an example of the output). 

2.5.2 Compute DC conductivity 

This feature is currently under development within the Virtual Cement and Concrete Testing 

Laboratory Consortium. 

2.6 Rheology 

This feature is currently under development within the Virtual Cement and Concrete Testing 

Laboratory Consortium. 

2.7 Elastic Properties 

This feature is currently under development within the Virtual Cement and Concrete Testing 

Laboratory Consortium. 
Estimated Chloride Ion Ditfusivily 

% Jm2 15:*7:06 MU3 

You submitted ulc fobwing nanWvduuc py”: 

. msratio - 0.40 

CsFadd * 5.00 

. vagg - 70.00 

. .lphph. - 0 75 

D canbclowercd by 

redu&sthcwlcmUo, 

lacrrarhsthcdcgrcc ofhgdntlonbyfoUowin(sood hspactices mu- idnveunaa 

- adwa supplmenttqcUu mamid(@ ar4 dag or sUca@me, ac) 

Figure 35: Example of an output page generated when the chloride-ion diffusion coefficient of concrete is estimated 

based on mixture parameters. 

2.8 Degradation 

Any assessment of durability depends on knowledge of the mechanism(s) by which degradation 

occurs. In VCCTL Version 1.1, degradation by leaching can be simulated. A model for degradation 

by magnesium sulfate attack is under development within the Virtual Cement and Concrete 

Testing Laboratory Consortium, and should be available in upcoming versions. 

2.8.1 Leach CH/cement 

This option can be used to selectively leach (remove) a portion or the complete volume of one or 

more phases from a hydrated microstructure. The calcium hydroxide (CH) and the initial four 

cement clinker phases all can be leached, and the user selects which phases to include in a specific 

execution of the algorithm. 

The input form for the leaching simulation is shown in Figure 36. The fields are: 

Random number seed The user must enter a negative integer (in the range [-32767,-11) in this 

field. See the description in Section 2.2.2 for more information on the purpose of random number 

seeds in VCCTL. 

Microstructure to leach The user must supply the file name of the microstructure to be leached, 

complete with any extensions. 

38 
Figure 36: Form for launching 8. simulation of leaching of one or more phases from a cement paste microstructure. 

Name of leached image A new file name, in which to store the microstructure after leaching, 

must be provided. If the file name already exists, the user will be notified and asked to specify a 

different iile name. 

Phases to leach Currently, the user can select to leach any combination of the following phases 

from a cement paste microstructure: CH, C3S; CzS, CsA, and C4AF. The default is to leach only 

CH. 

Termination of leaching Two options are available: 

1. Leach for a specified number of cycles (default 100) 

2. Leach the selected phases completely from the microstructure 

If the first option is selected, then leaching proceeds by the specified number of reaction cycles, 

progressing from the exterior of the microstructure inward. The reaction probability is specified by 

the user (see the next entry). If the second option is selected, then the microstructure is scanned 

once and all pixels of the user-specified phase(s) are converted to saturated porosity. 

Leaching probability If the user chooses to leach for a defined number of cycles, then a leaching 

probability (p~ in the range 0.0-1.0), is required in this field. 

E-mail address The program leach3d that performs the leaching simulation may take several 

minutes to complete. The VCCTL will automatically send a note to the email address provided 

when execution completes. If no email address is supplied, then a note will not be generated. 
NOTE: The VCCTL is set up to perform only one leaching simulation at any specific time. If the 

system is already executing leach3d for one microstructure when another request is submitted, the 

user will be notified to resubmit the request at a later time. 

2.9 Documentation 

The Documentation submenu contains further information about the Virtual Cement and Concrete 

Testing Laboratory, including links to 

this User’s Guide 

the NIST Electronic Monograph 

a Frequently Asked Questions (FAQ) repository 

a list of NIST personnel who are involved in VCCTL research 

3 Summary 

A detailed description of the web-based menu-driven interface to Version 1.1 of the VCCTL has 

been provided. The interface consists of a series of fill-in HTML forms that allow the user to specify 

input parameters for, execute, and view the results of various component programs of the VCCTL. 

The user is notified of the completion of program execution and, in a few cases, is sent a copy of 

the analysis results by e-mail. The system has been designed to bring the VCCTL to the user’s 

desktop computer, where a standard Internet browser provides a powerful connection to the world 

of virtual design, analysis, and optimization of cement-based materials. 

4 Acknowledgments 

The author wishes to acknowledge the NIST Prediction and Optimization of Concrete (HYPERCON) program for partial funding of this research. Additional funding for the VCCTL is provided 

by industrial partners in the NIST/Industry Virtual Cement and Concrete Testing Laboratory 

Consortium. 

40 
A Appendix A 

This appendix provides an example of how to create a blended (or composite) cement t,hat is ready 

bo be subjected to a simulation of hydrat,ion. As will become evident, careful considerat,ion of the 

mix design is warranted before "jumping in'' to t,he VCCTL menus. 

A.l Mix design 

0 CCRL Cement 140 with 5 '33 (by volume) total calcium sulfate, with the calcium sulfate being 

80 rC dihydrate and 20 % hernihydrat,e. Assume PSD of calcium sulfate phases is the same 

as that of t,he cement. 

0 Fumed silica, 4 7c of t,he t,otal solid mass 

- PSD to be approximated as uniform 3 pm spheres 

0 Fly Ashl 15 rC of the total solid mass 

0 PSD assumed to be bimodal, sharply peaked around 5 pm and 25 pm, 

Phase composition: 33 70 aluminosilicate glass, 39 % SiOZr 28 % inert, (on a volume basis) 

0 Morphology: predominantly monophase spheres 

0 Tot,al water-solids ratio is to be 0.5 

From this information, we can calculate the numbers of pixels of each generic t,ype of component 

needed (cement, silica fume, and fly ash). 

A.2 Calculation of target pixel numbers 

First, we need to know the fraction f3 of the system pixels that should be solid. After some algebra. 

the following formula can be derived: 

1 

fs = 1 + (w/s) ' pa (4) 

where w/s is the water-solids ratio (0.5 in this example) and p;. is t,he specific gravity of the solids, 

which in this case must be taken as a weighted average over all of the solid phases as follows: 

where pref is the specific gravity of a phase chosen as a reference. In Eq. (5), it is assumed that, there 

are k solid phases, and that, the i-th phase has specific gravity pi and volume fraction fi (fraction of 

the total solids, not, the system). The sum is taken over all the phases except, the reference phase. 

For this example, we are requiring that t,he mass fraction of fumed silica is 0.04, that of fly ash 
is 0.15, and that of the cement (clinker plus gypsum) is 0.81. Therefore, we need to convert mass 

fractions to volume fractions. For each component i z 1, this gives an equation of the form 

Again, for this example, k = 3, and we take the cement (clinker plus gypsum) as the reference 

“phase”. Examination of the previous equation reveals that we must know the specific gravity of 

the cement (plus gypsum). We calculate this using an equation like Eq. (5): 

Pcernent = Pclinker f fgyp (Pgyp - Pclinker) + fherni (Pherni - Pclinker) ( 7) 

Our mix design dictates fgy, = 0.04 and fhemi = 0.01. Furthermore, examination of Table 1 gives 

pclinker = 3.2, psvp = 2.32, and Phemi = 2.73. Therefore, substitution into the previous equation 

gives pcement = 3.16. 

Next, for this example Eq. (6) expands to the following coupled equations, where we substitute 

pi = pcernent = 3.16 

~FS = (3.16 + ~FS(PFS - 3.16) + ~FA(~FA - 3.16)) (8) 

 FA = (3.16 + ~FS(PFS - 3.16) + ~FA(PFA - 3.16)) (9) 

PFS 

PFA 

where subscript FS denotes fumed silica and FA denotes fly ash. Substituting in the values from 

Table (1) and the mass fractions required by the mix designs gives 

~FS = 0.050 

 FA = 0.182 

fcernent = 1 - ~FS - FA = 0.768 

We may now substitute these values into Eq. (5) to find the average solid specific gravity: 

pa = 

= 

Pcement + fFS (PFS - Pcement) f fFA (PFA - Pcernent) 

3.16+0.05(2.2 - 3.16) +0.182(2.55 - 3.16) 

= 3.00 (13) 

And, having a value for pa, we may substitute into Eq. (4) to find the volume fraction of solids 

in the system. With w/s = 0.5 from the mix design, Eq. (4) gives fs = 0.4. Thus, because there 

are 1M (one million) pixels in the system (100 pixels in each dimension), the target for the total 

number of solid pixels shall be 0.4M. Therefore, immediately we may derive the number of pixels 

needed for fumed silica and fly ash, 

NF~ = 1 x lo6 fs fps = 20000 (14) 

NFA = 1 x lo6 fa FA = 72800 (15) 

Ncement = 400000 - 20000 - 72800 = 307200 (16) 

Finally, with this information for the numbers of each type of generic particle, we may begin to 

create the three PSD files that are required. 

42 
A.3 Creating the PSD files 

A.3.1 Cement 

To create the cement PSD file, enter the Build Microstructure menu and click on the Create a 

PSD file submenu (see Section 2.2.1). Choose ”cementl40” from the pull-down menu for CCRL 

Cement 140. Click “Submit, ‘I, and when the next page is displayed, scroll down to the form entry 

for Total number of pixels. Enter 307200 in the field and then click anywhere outside that, 

field. The Javascript automatically calculates the number of particles of each size. Aft,er it has 

completed, the total number of pixels has changed to 307210. This value is wit,hin 0.003 Li: of the 

target value, so we will accept it and save the file by entering as excement in the PSD file to 

create field below (see Fig. 37). Pressing ”Submit” will save the file as excement .psd. 

..................... ~ .....,..... ~~~ ...... ~ $ 

L.~ .................. .. .. .....,... . . .. ... . . , . . ..... ..... ....., 

Figure 37: PSD form for creating example cement PSD file. 

A.3.2 Fumed Silica 

Again click on the Create a PSD file submenu (Sect,ion 2.2.1). This time, it does not matter 

which cement is chosen from t,he pull-down menu because we will modify t,he mass fract,ions such 

that only 3 pm particles are created. This time, as already mentioned, manually enter 0.0 for all 

the mass fractions in the table except that for 3 pm, which should be changed to 1 .O. Next, enter 

a value of 20000 in the field for Total number of pixels and click anywhere outside that, field. 

The Javascript now determines that there should be 1053 particles of size 3 pi> and because each 

of these particles is comprised of 19 pixels, this sums to 20007 pixels, within 0.04 % of the target. 

(see Figure 38). Save this file as exf s .psd by entering exf s in the PSD file to create field, and 

press “Submit“ 

A.3.3 Fly Ash 

Again click on the Create a PSD file submenu (Sect,ion 2.2.1). Once again, it does not, matter 

which cement, is chosen from t,he pull-down menu because we will modify the mass fractions such 

that only 5 prn and 25 pm particles are created. Press “Submit”. This time, manually enter 0.0 

for all the mass fractions in the table except that for 5 pm, which should be changed to 0.2, and 

43 
I .-, ~ 

. . 

Figure 38: PSD form for creating example fumed silica PSD file. 

that for 25 pm, which should changed to 0.8. Next, enter a value of 72800 in the field for Total 

number of pixels and click anywhere outside that field. This time, Javascript now determines 

that there should be 196 total fly ash particles, seven having diameter 25 pm and the remainder 

having diameter 5 pm. The total number of pixels is 72828, which is within 0.04 % of the desired 

value. Save this file as exfa.psd by entering exfa in the PSD file to create field, and press 

“Submit”. 

A.4 Making the L‘generic” microstructure 

Click on the Generate initial microstructure submenu (Section 2.2.2) of the Build Microstructure menu. Because we will be creating the microstructure from existing PSD files, 

click the button labeled “Read particle sizes from file(?.)”. We will choose to not add an aggregate 

particle, and we will also not select flocculation. The dispersion distance will be kept at its default 

value of zero (pixel units). 

A.4.1 Sulfate additions 

Recall that the mix design in this example requires 5 % calcium sulfate by volume, with 80 % of 

it being the dihydrate form and 20 % being the hemihydrate form. Therefore the three text boxes 

should be filled with 0.05, 0.20, and 0.00, respectively, as shown in Figure 39. 

Figure 39: Values for sulfate additions based on example mix design 

For the particle size distribution files, enter excement.psd, exfs.psd, and exfa.psd in the 

fields for Cement, Pozzolan, and Fly Ash, respectively. Save the microstructure as example .img 

by entering example in the Name this microstructure field, and press “Submit”. 

44 
A.5 Distributing the cement phases 

The next, step is to distribute the four major clinker phases among all the generic cement particles. 

To do t,his, click on bhe Distribute cement phases submenu (Section 2.2.3) in the Build Microstructure menu. Because we are trying t,o model CCRL Cement 140 in this example, select 

kement,l40” from t,he pull-down menu. Press “Submit,“. 

In the next form that is displayed, scroll down to t,he main part of the form. Enter a negat,ive 

ra,ndom number if desired, or just accept the default number. In the next field, enter example. img 

as the initial microst,ructure file (the one just, created in the previous step). For an output microst,ructure image file, enter examplea. The numbers in the t,able are automatically loaded from 

the database for CCRL Cement 140, so there is no need to adjust, them. Enter your email address 

in the appropriate field. Print t,his form from your browser, or record the volume fractions and 

surface area fractions for later comparison, and then press “Submit,”. The calculation should t,ake 

20--60 min. 

A.6 Checking the volume fractions and surface fractions 

It, is generally good practice to check that t,he dist,ribution of clinker phases produced satisfactorily 

accurate resulds for the volume fractions and surface fractions of t,he clinker phases. Click on t,he 

Phase statistics submenu (Section 2.4.1) in the Analysis menu, enter examplea. img (the output 

file from the previous step) in the text field that appears, and press the “Submit” button. Thc 

volume fractions and surface fractions for the four major clinker phases are displayed near t,he top 

of the table that, is displayed. The values should agree to wit,hin a few parts in the third decimal 

place. 

A.7 Distributing the fly ash phases 

The final step in this example will be to distribute the fly ash phases amongst the generic fly 

ash particles. Click on the Distribute fly ash phases submenu (Sect,ion 2.2.6) in the Build 

Microstructure menu. Ent,er a random number or accept t,he default value. 

Because the mix design specifications in the example suggest that each particle is composed 

of one phase predominantly. we will elect to distribute the fly ash phases randomly on a particle basis, by selecting the radio button next to that opt,ion. The initial microstructure file is 

examplea. img (the out,pnt file from distributing the clinker phases). The particle image file should 

be the name of the generic microstructure image (in dhis case example. img) except, with a “p” as 

t,he first charact,er. Enter pexample . img in this field. The new microstructure file name should be 

exampleb. img so enter exampleb in the field for New microstructure file name. Recall from 

earlier in the example that t,he number of generic fly ash pixels is 72828; enter this number for 

Number of fly ash pixels. 

The mix design in this example specifies that the fly ash is composed of 33 70 alumiuosilicat,e 

glass, 39 % silica; and 28 % inert filler. Therefore, enter 0.33 and 0.39 in t,he aluminosilicate glass 

and silica t,able rows, respectively, and make sure all the others are set to zero. The remainder will 

be assigned as inert filler automatically. Print out the form for future records. and then press the 

45 
“Submit” button. The computation should take only a few moments, so there is little need to enter 

an e-mail address. 

B Appendix B 

Phase ID Phase ID 

Saturated Dorositv 0 Ettringite 19 

C3S 

CZS 

(33.4 

C4AF 

Gypsum 

Hemihydrate 

Anhydrite 

Pozzolan 

Inert 

Aggregate 

AS glass 

C3A (fly ash) 

Generic fly ash 

CH 

CAS2 

C-S-H 

1 

2 

3 

4 

5 

6 

7 

8 

9 

11 

12 

13 

14 

15 

16 

17 

18 

Festabilized Ettringite 

AFm 

FH3 

Pozzolanic C-S-H 

CaClz 

Friedel’s salt 

Stratlingite 

Secondary gypsum 

Absorbed gypsum 

Dried porosity 

Empty dry porosity 

Empty porosity 

20 

21 

22 

23 

25 

26 

27 

28 

29 

47 

48 

49 

Table 2: Identification numbers for all phases recognized by VCCTL Version 1.1. 
References 

[l] D.P. Bentz. Cemhyd3d: A three-dimensional cement hydration and rnicrost,ruct,ural development modelling package. version 2.0. NISTIR 6485. US. Department, of Commerce. April 

2000. 

[Z] D.P. Bentz. Threcdimensional comput,er simulation of cement hydration and microstructure 

development. Journal of the Americal Ceramic Society, 80(1):3-21, 1997. 

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in t,he case of tricalcium silicat,e. Materials and Structures, 27187-195, 1994. 

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Cement and Concrete Research. 25(4):779~-789, 1995. 

47 
[13] D.P. Bentz, E.J. Garboczi, C.J. Haecker, and O.M. Jensen. Effects of cement particle size 

distribution on performance properties of cement-based materials. Cement and Concrete Research, 29( 10): 1663-1671, 1999. 

[14] D.P. Bentz, E.J. Garboczi, P.J.P. Pimienta, and W.C. Carter. Cellular automaton simulations 

of surface mass transport due to curvature gradients: Simulation of sintering. In Synthesis and 

Processing of Ceramics: Scientific Issues, number 249 in MRS Proceedings, pages 413-418, 

1992. Available at http://ciks.cbt.nist .gov/-garbocz/paper36/paper36.html. 

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NISTIR 6050, U.S. Department of Commerce, August 1997. 

[17] Number 04.02 in Annual Book of ASTM Standards. ASTM International, West Conshohocken, 

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