Effect of Particle Size Distribution of Metakaolin on Hydration Kinetics Of

This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. 10.1111/jace.16467doi: lead article this todifferences as version between this andtheof Pleasecite Version Record. been and throughtypesetting, proofreadingwhich may thecopyediting, process, pagination This article undergone has for and buthas accepted been not review publication fullpeer hydration on kinetics tricalcium of silicate (C focusThe this of study is to elucidaterole the of particle sizedistribution(PSD) of metakaolin (MK) Abstract 3. 2. 1. 20 µm were used:fine pastes, MK] prepared using physicalboth experiments and phaseboundary nucleation and growth (pBNG)simulations. [C Effect of Particle Size Distribution of Metakaolin on Hydration Kinetics of Accepted Article Engineering, Missouri University of Science and Technology (S&T), Rolla, MO65409-0340 Assistant Professor (Email: [email protected]), Department Materialsof Science and 65409-0340 Environmental Engineering, Missouri University Scienceof and Technology (S&T), Rolla, MO Assistant Professor (Email: [email protected]), DepartmentCivil, of Architectural, a Engineering, Missouri University of Science and Technology (S&T), Rolla, MO65409-0340 Graduate Research [email protected]),(Email: Department of Materials Scienceand – Articletype : Article ADITYADR KUMAR (Orcid :ID 0000-0001-7550-8034) 32 Aditya Kumar, Assistant Professor, Department Materials of Science Engineering& µm ; and coarse; MK , with particulate sizes< intermediate 20 µm; B49 B49 McNuttHall, 1400 N. Bishop, Rolla, MO 65409-0340 JonathanLapeyre Missouri University of Scienceand Technology MK 8% mass , with particulatesizes 32 > or 30% Email: [email protected] Phone: +1- Tricalcium Silicate * Corresponding Author 1 mass , Hongyan Ma 3 MK, wereinvestigated. Three differentPSDs of MK S-T 1 ) pastes. ) Investigations were carried out utilizing 573 -341-6994 2 and Kumar Aditya µm . Results showthat correlation the MK , with particulatesizes between 3*

nd 3 S + aluminate ions adsorb onto C and fineMK abilityto the intermediateof dissolve MK to rapidly other PSDs, theintermediate shows MK reversal bothlow at and high replacementlevels . growth effects and growth of calcium silicate hydrate When(C-S-H). C This article isprotected rights by All copyright. reserved. =H H * reactiona is space-filling hydrate (especially when compared itsprecursor,to CH)and contributes produceto C-S-H (19 chemical reaction of the aluminosilicate/silicateadditive portlanditewith (CH or calcium hydroxide) pozzolanicreaction incementitious environments(9,14 aluminosilicate,as well as strength) theof bulk material(8,10,13). Although fillers are typically assumed to inert,be connectivity within the microstructure,thus leading to improved properties (e.g., compressive additional C-S-H formed as a result of the filler effectresults in improved solid- substrates heterogeneous for nucleation and subsequent growth C-S-H nucleiof effectphysicala is mechanism, where hydration productin cementand C furnaceslag, and fly ash) widely-availablewith and abundantaluminosilicate (e.g., materials waste glass, calcined clays, blast benefitsThe partially of replacingportlandordinary cement(subsequently referred to as cement) tricalcium silicate(C Keywords particulates MK doesnot necessarily earlyenhance age hydration C of nucleation growth of C-S-H. Overall, the results suggestthat grinding based enhancementin SSA of dissolution sitesC-S- and 8% behavior of C between specificsurface area (SSA) of MK’s particulate pozzolanic effect areformer altered accounton twoof effects exertedthe additive, by thatfiller is, effect and aluminosilicate material(i.e., [cement/C Whencement tricalcium or silicate (C environmental effects (i.e., 1.0. Portions of the manuscript will implement standard cement chemistry notation: C = CaO, S = SSiO C= CaO, notation: chemistry cement standard implement will manuscript the of Portions

Accepted Article mass

Introduction 2 , $ = $SO , ), fine), of Such reversal fillerof effect is also observed incase the intermediateof MK; butunlike the both fineand coarseMKare reversed, leading suppression to of C-S-H nucleation and

3 MK – . . 3 which results infaster release aluminateof [Al(OH) Sin first hoursnonlinearis 72 and non-monotonic. Atreplacement low of C , , tosome extent, coarse an (7 – d 3 9) S);metakaolin; filler effect; hydration kinetics;particle size – 23) . Both. effects enhance formation calcium of silicate hydrate(C-S-H H nucleation sites on the substrates’ surfacesand suppressingpost the ha . additionalThe (pozzolanic) C-S-H formed asresult a of the pozzolanic si CO ve been ve investigatedwidely partas broad of a strategy to the offset lica based(e.g., silica fume),material additivesare also able to undergo 3 S and MK particulatesS and MK andsuppress C 2 emissions and energy consumption)of cementproduction

3 S systems),albeit throughdifferenttwo processes. fillerThe 3 in S: theS: major phasein are cement) partially replaced withan fine particles theadditiveof act as energetically favorable 3 S + aluminosilicate]S + pastes),hydration kinetics the of MK asact fillers,and facilitateadditional nucleation – with fasterkinetics compared both to coarse 3 s and the consequent alterationin hydration S – 18).The pozzolanicpertains reaction to replacement increases to 30% 4 - ] ions inthe solution. The 3 S hydration byblocking C 3 S. to -solidphase (8 – 12) . The mass 2 * . 3 , A = AAl , : S (i.e., atS Thisdue is , the, filler (1 the major – 3 6) S - 2 . O 3 , [ diminishment or reversed (i.e., suppression, rather than enhancement, of C-S-H and nucleation growth). Such replacement levels (i.e., ≥20%), however, the filler effect of is MKeithersubstantially diminished or particulates which of highlyare susceptible to effects of particle agglomeration. At higher effectfiller of MK is substantial,even superiorand in comparison that to silicaof fume, fine the and g al negligible at early (i.e., ages upto 24 hafter mixing), and, therefore, do C among these is a recent study conducted byLapeyre and Kumar (9), whichin hydration behavior of haveexamined, and attempted decouple,to the andfiller pozzolanic contributions MK. of Notable termsin improvement of inproperties of the bulk material (31,42), th 23,39–41). While majority these of studies have focused onquantifying aforementioned the benefits other as calcined clay minerals,when used to replace cement pastes, in concretes, mortarsand (21– C andenhanced overall reactivityof MK, as compared tokaolin, in alkaline conditionscement of and energetically lessstable than crystalline the structure, thus leadingfaster todissolution dynamics crystal structure kaoliniteof into anamorphous network (34,35). bondscovalent between hydroxyl groups and aluminum octahedral groups transforming the triclinic mullite and/or γ between This article isprotected rights by All copyright. reserved. impede post-nucleationits growth.Such inhibition of C topographical sites C-S-Hfor nucleation; furthermore, samethe adsorb onto anions C-S-H and reported that the aluminate adsorb anions onto C aluminosilicate material derived from calcination kaolinite of (Al focusThe this of study is metakaolin (Al permeability and improving(24 strength towards enhancement of Al(OH) 3 3 teration in hydration behavior C of S pastes (21,36Spastes AcceptedS in[C Article rowth ofrowth C-S-H onits particulates’ surface. A There There have been several investigations identifying andbenefits assessing of the MK, as well 4 - 50 3 ] S + MK] pastes were examined. The studyconcluded that pozzolanicthe activity MK of

in in the solution, released from dissolution the MK. of More specifically, (9) the study 0°C – - reversalof MK’s effectfiller is attributed theto abundance of aluminateanions Al 800°C (29 – 38). 2 O 3 , significantly, attenuating its pozzolanic reactivity (31 thebulk material’s – 32).Calcination kaolinof above900°C transforms MKinto crystalline 3 S. MK, however, servedoes as a filler, facilitates and nucleation 2 Si – 28). 2 O 7 physical properties, such as loweringwater : subsequently : abbreviated as MK), an anhydrous 3 S t and MK particulates’ surfaces, inhibitand low replacements up (i.e., to 10% 3 S hydration has also been reported in other 2 Si Th 2 O e amorphous e structure is ere are only studies afew that 5 (OH) es not cause significant 4 – ) clay at temperaturesat clay ) 33) . Calcinationbreaks mass ) of C of 3 S, the is

can K MK on hydration kinetics of C coarser ones (48–52). Prior literature, however, provides little information on the effect of PSD of studies that have shownthat in aqueous environments, particulatesfiner dissolve faster compared to such factor is the particle size distribution (PSD) of MK. This basedis on avast number prior of affects MK’s dissolution would also affect overall hydration of the host material.cementitious Once role in altering the hydration behavior of cementitious be could systems. arguedIt that anyfactor that This article isprotected rights by All copyright. reserved. pozzolanic effects,present but fewer complexities compared to cement. evaluate such behaviors in single-compound systems (e.g., C sequester to the filler and pozzolanic effects of MK from Thus, overall effect. its it is important to ettringite) (1,21). Such andreactions, their net effect on cement’s hydration behavior, make difficult it hydrates (e.g.,strätlingite andhydrogarnet) and alterations in stability sulfate-bearing of phases (e.g., i conc component material, consisting other of phases C (e.g., aforementionedpair studies of (53,54) are significant, the utilization of– cementwhich multi- a is and CH occur) pastesin such was significantly delayed. While insights provided by the negligible; furthermore,the onset of acceleration period (i.e., whenmassive precipitation of C-S- with MK comprised of particulates coarser than the aforementioned the one, filler waseffect 2 than µm) accelerated –albeit only slightly– hydrationthe of cement.However, inprepared pastes aluminate-rich systems, for example, whenAl C N ts ts particulates. This becauseis in cement the paste, aluminate ions released from dissolution of M 3 aAlO urtis and Lagier and Kurtis (53,54) wasit shown that fine MK particulates (90% particulatesof finer Accepted Article S/cementpastes are provisioned Al with undergo reactions with paste components other than C lude that the effects monotonically of MK scale with fineness SSA: (i.e., specific surface area) of 2 andAlCl Based on above discussion, apparent it is that dissolution dynamics MK of play a significant (43–47). 3 ) 3 S orcement systems. In two separate studies, conducted by Justice and 2 O 3 2 nanoparticles highly-soluble and aluminatesalts (e.g., O 3 -doped C 3 A) in additionA) in C to 3 3 S, S (instead of pure C 3 S) that stillS) that feature the filler and resulting precipitation in of secondary 3 S – makes difficultit to 3 S) used is or when H K mo to former respectWith to the method. uniquethree comparedPSDsas and sizeofbetterclassification amounts) particulatesinto superior asyieldsparticulate however, latter(i.e.,itthe greater wasresulted chosen in instudythiswet-sieving andIt methodswereclarified is attempted that bothmethod. dry- wet-sievinga modified utilizing processpowder, based were the generated (PSDs) frombulk differentsizes of MK particleThree distributions % inshown Metastar HP501),in terms of percentagesmass of as determinedoxides fromx-ray florescence, Triclinic C particulates resultantand the effect C on simulations to elucidate, from a mechanisticstandpoint, the correlation between of MK SSA beenimplemented. Emphasis hasbeen given to consolidate results obtained from experiments and thermogravimetric analysis)and phase boundary nucleation and growth (pBNG pastes, acombination experimental of methods (e.g., isothermal microcalorimetry and TGA: This article isprotected rights by All copyright. reserved. en wassetat MK toproduceawith mix) wet mixing (usedforthe Notably, of distilledofamount water different batches eachofMK. PSD containingonly 0.80% 0.25%± residualof free lime (i.e., powder was evaluated precursors.calcite Details regarding synthesis (i.e., pastes. Pastesfeaturing three different PSDs of MKand twodifferentC investigatesThis study the influenceof PSD of MK itson pozzolanic and filler effects in[C agglomeration. Results obtainedagglomeration. PSDfrom aredeterminations shownin agitatedtopreventimpulse secondsand forthirty withisopropanol, ultrasonic werepowdersthis, suspendedTowards the in S3500). (SLS)analyzer (Microtrac scattering coarse withareincreasingPSDsofreferred intermediate and three fineness MK toas MK, MK, fine µm;(iii) and coarse 32 µm; < (i.e.,intermediate20 diameters) (ii) and 32 20µm through of part the wetAs finalthe(56). sieving process, the (duringtherefore,and, process), not does the rehydrate wet-sieving conditions, and (STP) standardpressure temperature under that haveshown results and obtained XRDofkaolin, fromform shown), studies (notprior 2.0. mass

Accepted shakingaftersurehomogeneity theAlthough two-hour process. Article difications in the wet-sieving method wereensurewet-sievingmadein methodthe consistency difications to between

Materials and Methods 8%

Al 2 MK mass O Table 1 3 3 S( , with , minor titanium and iron oxidecontaminants. and 30% ,. respectively Ca 3 SiO . As shown. inthetable, theMKpowder 5 -T mass 1 ) was ) produced solid-statevia thermalprocessing of reagentquartzgrade and – )have been used. Towards examination of hydration behavior of C using diffraction x-ray and Rietveld analyses – µm particulate with 32µm sizes > All PSDs of MK, as well as of C ofMK,wellPSDs as All as of sieves to yield(i)PSDs:sieves three uniqueto fine 3 S hydration behavior[C in the ≈ are – aforementioned ASTM standard, minor standard, aforementioned ASTM 200 mL, and the was200 and mixture mL, handtoshaken by with sizesparticulate ranging 20-and- between presented elsewhere(9). After synthesis, t CaO is “as composed of 51.30 % . 3 on S, were measuredaS, staticwere light using Insubsequentthe the sections, ). The). composition of - received” the ASTM C325-07(2014) ASTM(55) the MK 3 S+ pastes. MK] does notdoessignificantly – to be nearlypure phase C 3 S mass replacement levels PSD of MK – re withparticulate sizes is dehydrated the vertbackkaolin to Figure1 ) MK simulations have mass MK

wassifted SiO (Imerys-Kaolin 2 . The and 47.80 3 S + MK] 3 S in such he final is 3 S,

; This article isprotected rights by All copyright. reserved. pastes, the mass-basedwater- PSDs)at two different mass replacement levels: low (i.e., allIn pastes. binary(i.e., [C ratiomass ( [C (62, method are expected above to besmaller than those from derived Brunauer-Emmett-Teller the are(62,63). BecauseSSA overall ofthe negligible assumptions, these SSAsthe reported spherical sizeparticle(d median Priorconducting to the TGA experiments,the bulk isopropanol drained,was and samplesthe were such cases, isopropanol for 24 hours.In some cases, thesamples were keptisopropanol in for longer periods; in hydratedsamples (after undergoing hydrationfor 72 h)werefirstly crushed, andsubmerged then in SDT-Q600thermogravimetric analyzer (TGA)was used identificationFor andquantification of hydrates(i.e., C-S-H andand CH) calcite(if any) plugging intheenthalpy of dissolution the enthalpyof dissolution and of MK, to subsequentlyestimate the degree reactionof ( experiments wereprocessed two-steps, in as described in prior (9,16), studies three PSDs)with saturated solution lime at separate microcalorimetry experiments wereconducted pastes on prepared by mixing (for allMK analyses was 484 J. g reaction ( determinethe degree reactionof ( experiments wereprocessed temperature of 20°C ±Heat 0.1°C.evolution profiles collected frommicrocalorimetry the Instruments)isothermal conduction microcalorimeter, programed to maintain kinetics C of dispersion(or suppressed agglomeration of particulates)broughtabout by the dispersant.Hydration ( resultincomplex alterations inC polycarboxylateas polymer)ether was avoided. This is becauseprovision the dispersant could of the pastes,the utilization of dispersants(e.g., high-range water reducing chemical admixturessuch system), 8% thatall areare particulates fromon premised estimations ofSSA assumptions PSD the kg 29 m and intermediate,offine, SSAs coarseand µm,respectively148.00 and 16) 3 -1

Accepted Articlepastes S+MK] were prepared by themixing powders deionized with awater liquid- at fixed respectively; density theC of that woulddifficult be sequester to (andsubsequently analyze) from the effect dα/dt , 2 and that the effects of topographical roughness and internal porosity (57 ofthe thatroughnesseffects and topographical internaland porosity . l/s “fresh” mass 3 kg S in thepastes were monitor 63) ) ) of The0.45. mixing protocols (i.e., rate and time of mixing)were kept consistentfor -1 , and 30% , units h of ,C respectively.the For . isopropanol was used to replenish the oldperiodically one (i.e.,after every 24 h) C 3 S -1 . To monitor the dissolution dynamics of MKin C 50 mass -1 )intermediate,fine, for coarseand 3 ) of of ) C S + MK])S + pastes, C replacements by respectively. MK, It clarified is that in preparation of – to using a method employed in several prior studies (9,48,50,64) . By factoring the bulk density of MK (i.e., 2550kg. m the By bulkMK factoring of density 3 -C 3 S; the S; enthalpy hydrationof (48,64 S dissolution behavior and nucleation and growth theof hydrates 3 , fractionα, of C S ratios( 3 S was assumed to be 3150 kg. 3150 wasassumed m S tobe .

ed 3 MK Spowder,d the l/s for 72 hours after usingmixing a TAM IV(TA w/c 3 were estimated to be 672 m estimated 672 were be to of 0.45. Heat evolutionprofiles collected from such Swas partially replaced by(for MK the each threeof ) are ) 0.450, 0.489, and 0.643 for 3 S that hasundergonehydration) and rate the of . For arrestingFor hydration of C 8% 50 mass and7.78m wereµm562 and SSA ) and high) (i.e., 30% MK –

66) C of are -3 4.62 3 . S paste environments, Itclarifiedis that 3 2 S used for such . 00 to a kg 0% firstly determine constant µm, 28.530µm, µm, -1 3 , 80m , mass mass S in such pastes, of particulate )

in . (c -3 ) for α) In such pastes, a ontrol ), the 2 – . 61) kg to – MK -1 to on -solid , by 2 . . This article isprotected rights by All copyright. reserved. ( hydrate t envelops the N crucible andheated from room temperatureto aat 1000°C, temperature ramp-rate of oven-dried at 85°C for anhour.During theTGA experiments,samples the wereplaced in anAl The degree The hydration of of C except into the substrate(69,70). case, C on nucleated, the productsubsequently grows heterogeneouslysolid on substrate boundaries(in this nucleation event,and the productnucleation rate is zero atall timesafter such event. One assumed tooccur under growth aof hydration single (i.e., product C-S- pBNGThe model simulatesC infor brief; further details, readersare requested to referreferences to (9,50). assumptions andprinciples of pBNG the andmodel, their mathematical formulations,are presented (9,16,50,64,66). Therefore, avoid to replication information,of in this section,the underlying kinetics C of Amodified phase boundary nucleation and growth (pBNG) usedmodel was to simulate hydration suchphase For quantifications, delineatedmethods in studies prior (67,68) were adopted. from the experiments, wereused to quantify theamount CH of and calcite(if any)in thesamples within the TGA apparatus 3.0. he 2 Accepted Article gas,passing a constantat rateflow 100of mL. min function

Phase Boundary Nucleation and Model Growth Eq 3 S and . . 2 3 X(t) S and [C paste’s ) ) (16,66,69

MK describes temporal the evolutionvolume offraction reactantof transformed into

particulates’ 3 characteristics

S + MK] pastes

site saturation –

. 71).

The lossmass (TG) and the differential lossmass (DTG) patterns, derived

S as a functionSas a of time, S hydration asprocess a driven byheterogeneous nucleation and

surfaces)

(i .

.e.,density components,of chemical shrinkage,and The pBNGThe model hasbeenused in prior studies

conditions

Growth ofproduct the is permitted in alldirections

. H)

fixed a of density (69,70)

–

wherein all productnuclei form atgiven a

α(t)

-1

, was used , was to maintain an inertatmosphere

, is , calculated from

. Productnucleation is Eq . . 1 . Here, 10°C. min B w/c and), (unitless) ( ( 2 ( 1b 1 O 2 a ) 3 -1 ) . )

represents the replacement level C of specificeffects (e.g., inhibitionaluminate dueto ion adsorption).The otherparameter, fraction of MK, thatthe is, areafractionnot affected by particulateagglomeration and/or otherion- (9,16,74). Here, supercritical productnuclei unit per mass of C overallspecific surface area ( couplingBy product the nucleation density with the substrate’s inrate relationits to supersaturation inthe solution. and subsequentlyadopted in several studies(9,16,50,64,66), to capturechanges inC-S-H variation ingrowth rate is based an on implementation originally formulated the actual geometryC-S- of inrate thelateral direction. Such a directi on (i.e., perpendicular to the substrate’s surface), theoutward growth rate( parallel to the substrate’ssurface), the growth rate is isotropic; however,in the longitudinal to occur inan anisotropic fashion, whilevarying with respectIn to time.the lateral direction (i.e., for moredetails). It should benoted that inthepBNG model, thegrowth theof product is assumed ( density This article isprotected rights by All copyright. reserved. insuccessive three simulation steps. reaction ratesare within and (ii) 1%; the simulation output convergenceassumed is toreached have when: (i) the deviation between measured and simulated optimal functional form of optimum values electron microscopy (72,73,76))whereas Insteps. the first step, Mead-based simplexalgorithm (75) i beascertained forreproduction of the measured reactionare: rates WithinpBNG the framework, as described aboveand in references(9,50), the variables need that to In

Accepted Article 2 Eq. , I F density D is the f-Dawson function. The variables , µm a of MK -2

) and) outward growth rate [ (unitless) acts free a simulation variable(9)that represents the reactivearea density G

out

and is fixedat0.075 µm. h G H’s early out SSA

a MK

(t)

, which solid . It is clarifiedIt is . that duringaforementioned the optimizations, nisotropy in product’s , m -agegrowth, as observedin experiments (72,73). The temporal

3 useddetermineto optimum these values of variables in two

S by MK inthe paste. 2

. kg

are

I density C

subsequently used in the secondstep to estimate the

-1 3 , as shown, in S in the paste ( and G

out

-1

(a (a derivedvalue from scanning transmission k (t) a s

MK (h , µm.h are allowed vary.toThe first step yields -1

) and ) growth has been implemented to mimic

do Eq -1 N

es k ] of ] of the product(see references (9,50) s. 3 s. 3

g Nuc (i.e., C of

not changeby morethan ± (h , kg ,

-1 and

) are functions ) nucleation of

G C 3 out 4 S -1 (t) ), ) can) be estimated 3 the number the of S and particulates) MK , I density by Bullard(71),al. et , and G out ) is double) the a z MK

(% growth’s . ANelder- mass 10 -6 ), units ( ( 4 3

) )

(se At highreplacement level (i.e.,30% binarypastes superior is compared control to the paste. lowat replacement level of MK and later at ages arepeak faster(i.e., rates heat flow higher) are compared to that of the In summary,control paste. post-peak deceleration is slower(see three hydration atearly ages.Notwithstanding, at the age of72the h, cumulative heat releaseof each of reaction of C that ofthe control paste( resul followedperiod, by the fineand coarse control paste( three in C rate flow compared to the control paste.While peak the heat ( flow rates MK, intermediatethe suppresses MK nucleation and growth ofas C-S-H, evidencedlower by peak heterogeneous nucleation and subsequent growth of (9,10,15,49)C-S-H This article isprotected rights by All copyright. reserved. results [C of acceleration topeak, the and lower peak heat flowrateas comparedto the control paste. Akin to substantial prolongation of induction period,delayed occurrence theof main hydrationslower peak, in area pureC heatpeak flow rates (i.e., heat flowrates at the main hydration peaks) compared to the control (i.e., As MK. can be in seen Figure 2 4.1. Effect of PSD of Metakaolin on HydrationKinetics of C degrees C of hydration, however,progressively diminishes with age,and ultimately reverses producing greater additive’s particulates Figure 3 pastes surpass that of the control paste at 72 h( slowerdeparture from the main hydration peak), degrees the C of the main hydration peak( induction period, lowestslope accelerationof to theand thepeak, greatest delay in occurrence of effect on C 4.0. Figure Figure 3B

Acceptede Article 3

S hydration kinetics)do notexhibit monotonicrelationship with fineness of particulates, MK a Results and Discussion Figure 3A ts in ts lowerearly-age (e.g., at h)cumulative12 heat release allin by [C [C 3 S) paste. ThisS) paste. indicative is of

the add 3 3 shows heat evolution profiles of , it can be said thathighat replacement level regardless of MK, of the PSD (or S + MK] pastessurpasses that of the controlThispaste. because is in [C S + MK] pastesreliably showprolongation induction of the periodcomparedas to the 3 S hydration , which focuses the on first 24 h hydration.of As can beseen, all threePSDs of MK cause 3 3 S + 8% 3 S hydration in binarypastes compared tocontrol the paste S, itcansaid be provision that of MKin thepaste results inlower degree C of ), regardless), theof PSD throughoutof MK, the 72 hafter This mixing. isbetter shown Figure 2B itive’s mass

, hydration (i.e., MK’s) Figure 2A MK]pastes shown in am ). The). intermediate Figure 2C Figure 3B ong all[C , low at replacement level, bothfine and coarse produce MK greater particulates results in creation supplementary of sites for of ) mass ). Also, due tolower the slope post-peakof deceleration (i.e., C . the “fillereffect” 3 S + 30% As cumulativeheat release is direct a indicator degreeof of 3 Figure 2B S ) C of MK is [C suppressed earlyat ages.Such suppression C of , respectively., Such prolongation theof induction period 3 MK 3 S + pastes, MK] prepared by replacing Figure 2 mass S with ), and,), therefore, C prompts the largest extensionin theinduction MK] aspastes, evidencedthe by protracted Figure 3C (i.e., age≈ 72 h) MK , theintermediate has MK theprominentmost , whereinprovision additionalof solidsurface , hydration, host of the materialis suppressed ). Therefore,based on theresults shown in 3 S , the, degree of C 3 3 S hydrationS kineticsbeyond the S hydration [C 3 . . S + MK] pastes compared to Unlike thefine and coarse

an d, therefore,alterations in 3 S + pastes,MK] the all 3 S hydration in 8% [C mass SSA) theof 3 S + MK]S + C of 3 S 3 S 3 Swith ll 1 (h peak understanding,additional (i.e., calorimetric data parameters(9,10,16,64): inverse MK]+ pastesin relation to and PSD replacement levelproper of To gainMK. studies focused C on aluminate ions passivate thesurface of C pronounced as the content in MK of paste the increases( aluminate ion adsorption(which leads toinhibited dissolution of C turn,slowsC particulates’ surfaces blocks dissolution sites(e.g., kinkson etch pits C of ions fromdissolution the of MK. More specifically, the adsorption aluminateof ions ontoC prolongation theof induction perioddirectly is related to the releaseof aluminate (i.e., [Al(OH) magnifiesas the MKcontent inpaste the increases. Inprior a study (9), it reportedwas that such As canseen be ( Heat flowrate profiles substantial amount is of CH present,pozzolanic the activity of MKis upsurgeexpected to in equivalent amount) with CHis substantial(i.e., up to 20% canseen be in in [MK CH, at+ 1:1 molar pastes, ratio] preparedby mixing and MK CHwith waterat conducted to examine the reduction in CH contentandresultant the formation of pozzolanic C-S-H the lowcontent CHin of suchbinary pastes. To corroborate this,additional TGA experiments were dynamics of MK(this further is described in pozzolanic activity of MK in[C hydration behavior C of strongly suggests that withinfirst the 72 hafter mixing,impact the of pozzolanic activity of MK on hydrationis not significant thethat pozzolanic reaction(regardless between MK itsandof PSD) CHwithin thefirst 72 h of binarypastes invariably above stay dilution the line (at72 h,see hydration, observed at early ages,is reversed atlater ages corroborates the argument made earlier inthis sectionthat the MK-induced suppression C of CH contentsin binary pastes CH content with respect to decreasing C among allpastes,and even belowthe dilution line (which representsthe proportional decrease in to ≈24 h) beseen, a found toin be very good agreement with inferencesheat madethe from evolution profiles. As can (i.e., CH)contents thein pastes were measured,and plotted ( This article isprotected rights by All copyright. reserved. releaseprofiles ( inferencesThe degreeof of reaction C of ) )

Acceptedwere extracted from the heat evolution consolidated, profiles, and plotted ( Article -1 ), maximum heatrate flow (mW. g hydration t bothlow and highreplacement levels, the intermediatesuppresses MK early-age (i.e., up 3 S Figure 4C dissolution dynamicsand prolongs the induction period.Expectedly, these effects of Figure 5A Figures 2C of 3 S hydration in the presence of slightly-or highly-soluble aluminum-based(43 C . , Thissuggests thatin 3 shown in 3 , when adequate amount CHof present, is pozzolanic the reaction of MK S S ),the main hydration peakis delayed inall binarypastes; the delay in themost. is This evidenced by CHcontents that are consistently lowest . and This isin very good agreement findings with priorof (77 studies [C – 3 regardless theof PSD of MK 3 S + MK]S + pastes is S + MK] pastesMK] S + is insignificant. It is worth clarifyingthethat poor 3C Figures ) are qualitative in nature. Forquantitative estimates,portlandite mass 3 reduction in CH content, and formation pozzolanicof C-S-

3 3 S content inbinarypaste). At the age of h,72 however, the 2 S in [C S particulates and C 3 section 4.2 a S -1 mature ), and ), slope 3, 3 no S + MK] pastes madefrom thecumulative heat qualitatively contrastC t exclusively dueto slower the dissolution [C ). – 3 Rather, the limiting factor is expectedbe to S + MK] pasteMK] S + (i.e., after age>> 72 h), when is supportedresults by obtained from prior Figure 5A . of – Moreimportantly, as CH contents of are above the dilutionThis line. the acceleration regime (mW. g Figures4A and 4B Figures4A and 4B 3 ) S) becomeS) progressively more . This hypothesis 3 3 S surfaces(81,82)). This, in S hydrationkinetics in [C , quantitative Figure 5 ). resultsThe were of ), it), can be said time the to – l/s that the ) of As 0.45. .

3 – S 80), and80), C 3 3 S S 4 -1 - ]) . h 3 – H S - sup therefore, althoughintermediate the does MK not havethe largest SSA, its ability to passivate C the induction period and onset theof accelerationIn regime. a result, the aluminate ions from desorb C aforementioned aluminosilicatecomplexes C on and OH thepHcontacting of solution continues increase.to Ata critical pH, when the concentrations Ca of surfacesforming an electricdouble-layer). As C This article isprotected rights by All copyright. reserved. becorroborated later in the intermediate MK hasthefastest dissolution ratein C passivateto C between the aluminateions and Ca favorabledue to formationaluminosilicate of complexes,comprising ionic and of hydrogen bonds showed(43) that theabsorption aluminateof anions onto C 47) test test the veracity of the concept,additional calorimetry experiments wereconducted to monitor the solutionof [C contactingthe solution. It has beenargued that greaterabundance aluminate of inpore- ions fastest dissolution dynamics,consequently, and, promptsthe fastest release of aluminate ions in conceptthat of all PSDs (i.e., of MK fine, intermedia, and coarse),the intermediate hasthe one hypothesesThe derived from the results presented in 4.2. Effect of PSD on Dissolution Dynamics of MK S-H nucleation and growth ( insolution, the which essentiallylies at the originsuppression of C of intermediate MKis proficientmost (compared to the other PSDs releasing at of MK) aluminate ions intermediateMK suppresses C-S-H nucleation and growth the most. This suggeststhat the “poisoning” of blocks C-S-H nucleation siteson MKsurfaces, thus diminishingand ultimately reversing(akin to passivation MKparticulates’of surfaces in addition to those of C dissolution ofin MK) thesolution of such pastes MK’s serveto as filler a notis just diminished but reversed additionalof nucleation siteson their Atsurfaces. high replacement however, level, the ability of MK the fineand coarse act MK as fillers,and enhancenucleation and growth C-S-H throughof provision than those theof control paste.These results, therefore,suggest atthat low replacement level, both the control paste.In contrast,highat replacement level, both calorimetric parameterslower are h Going back to Accepted igherheatpeak flow rates ( Article or aluminosilicatecompo erior comparederior the fineto (with largest and SSA) coarse(with lowest SSA) filler effectattributed is tothe higherconcentration of aluminate( ions - ions in the solutionare elevated to it ’s potential to prolong theinduction perioddelay the and main hydrationis peak) 3 3 S + intermediateS + is paste MK] principal the reasonC for Figure 5 ) its ) filler effect. S surfaceis directly linked with the release aluminateof ions, itis hypothesized that , it , canseen be that low at replacement level,fine and coarseMK produce section 4.2 Figures 5B Figure5B unds Figures 5B (83 2+ .

and OH – ) and) slopes of acceleration regimes( and 85) and 3 . Using molecular dynamics simulations, Pustovgar etal. S surfaces(44,82). This event is markedtermination by of 5C CH saturation level (i.e., pH 12.68≈ - ions (thatremain inthevicinity to C ). 5C 3 S continuesto dissolve (thougha slowerat rate), the . 3 clearly showthat, among the three thePSDs of MK, S surfacesbecome thermodynamicallyunstable; as Thelarge abundance aluminate of ions causes . As reported ina prior study(9) section 4.1 3 S pasteenvironments. This hypothesis will 3 S particulates’ surfaces is energetically Figure 5A 3 S particulates. Such passivation are premised centralon one 3 3 S dissolution ( S hydration suppression . , it is, it interesting that Figure 5C re MK sulting from (44,48,66,82) . Sincethe ability 3 S particulate Figure 5A , )compared to 3 this reversalin S surface(and, ), ) the andC- To to 2+

This article isprotected rights by All copyright. reserved. 4.3. conducted using the pBNG model. kinetics. Validation thisof hypothesisprovided is in intermediatelarger MK is thanof that fine MK (and coarse MK), resulting inthefastest dissolution agglomerationor aluminate-ion adsorption, and, therefore, able to partakein dissolution) of possibleit is th lower SSA comparedthe to fine MK, but is notexpected beto susceptible to agglomeration. As such, fineparticulates surfaces, causedby aluminateions released from theinitial (and rapid) burst dissolutionof of the surfacearea, thus causing decelerationdissolution of kinetics; and (ii)passivation particulates of MK agglomeration(i) itsfineof particulates, which, inturn,in results significant reduction of overall known,it is expected that slower dissolution kineticsoffine the due MKis to the following reasons: relationship with SSA of MKparticulates. Although theexact reasons for this anomalynot are therefore, counterintuitive dissolutionas the kinetics notdo appear to followmonotonic a fine,followed by the intermediateand then by the coarse MK. The results shown in (reported in thanfine the and coarse As canseen be in composition remainsin vicinityCa(OH) of Ca shownhave that inC saturated calciumwith hydroxide[i.e., Ca(OH) dissolution dynamics of MK insaturated lime solution. solventThe was chosen to be particulates’ surfaces (see theboth fineand coarse MKserve as fillers and enhanceheterogeneous nucleation on of their C-S-H particulates level. plotsThe showthat atlowreplacement level(i.e., Figures7 differentpastes, weresubsequently consolidated, and plotted ( results(figure notshown). Optimum values of the aforementioned simulation parameters, for the [ participating inproductnucleation ( following simulation variables:product nucleation density( embedded within thepBNG model, invokedwas tothe reproduceinput profiles by optimizing the calculated from calorimetry profiles)pastes of wereused inputs. as simplex The algorithm, (described in gainfurtherTo insights into the role of PSD of MK on C G out Accepted Article2+

Numeric , OH

(t)]. - Through such optimizations, the pBNG model able was to reproduceexperimental the ions at millimolar levels,(mM) H and A and – section 2.0 al section 3.0 regardless of the PSD of MK atthe “reactive surface area” Simulations of Hydration Kineticsof [C 7B . The intermediate whichMK, comprises particulatesof between 20-and-32 has µm, Figure 6 show variations in 3 S pastes,following few a hours after themixing,pore-solution [consisting of ), it be would expected thatdissolution dynamics wouldfastestbefor the ) employed. was Experimentally derived reaction rates(i.e., MK , the intermediate MK, indeed, dissolves and faster, to greater extents, Figure Figure 7B throughout the 168 haftermixing. Based theon SSAs of the PSDs of MK a ). Dueto its higher SSA, expectedly, the fine MK enhances MK a MK ), and ), the time-dependent outwardgrowth product rate of and 2 saturation levelfor protracted periods – is available for C-S- (i.e., surfacearea thatunaffected is by particle I 2 2 density ],because several paststudies(48,65,66,71,86,87) SiO 4 , respectively,in relation theto MK replacement 2- section 4.3 /H 3 3 3 S hydration kinetics SiO S MK] + Pastes 8% 4 I mass - density ions at ions micromolar level](µM) ), with the aid of simulations H Figure 7 majority surfacearea of of MK ), reactive), fraction area of nucleation.In accordancewith this, ).

, the the pBNG model .

Figure Figure 6 dα/dt DI -water ,

MK are,

I density

’ concurrentreduction in replacement level, owing to thereduction inreactive surfacearea MKparticulates of ( coarseMK are able to exertfiller effectand enhance thenumber nucleiof inC-S-H paste. the At high pBNG model and its implementation. experiments. Itis posited thatsuch similarity between experiments and simulations validate the similar to thoseexhibited by calorimetric parameters in (shown Figure 7C to estimatethe total numberof supercritical product nuclei formed theat nucleation( event twoThe simulation parameters, surfacepassivation induced by aluminate ions. The MK. reduction in MK passivation causedrapid by release( control paste( almost b consistently belowthe control paste rendered unreactive( in the diminishment reactiveof surface areaand blockage ofpotential sitesfor C-S-H nucleation agglomeration and(aluminate ion induced) thewith discussion in significantly lower compared tothe control paste ( SSA) This article isprotected rights by All copyright. reserved. G evolution of C-S- [ rate otherThe simulation parameter optimized frompBNG simulations is the outwardgrowth product H nucleation sites. release of aluminateions, which thenpassivate the that fasterdissolution kinetics intermediate of MK previous (as shown At hi adsorb on rapidcauses releaseof aluminate into ions the contacting solution theof filler effect. Thisreversalattributed is fasterto its dissolution kinetics (see morethan the coarse intermediate MK. The MK, however, causesa decline in suggested inprior a study(9),that the residual aluminate ions present inthesolution (i.e.,ions that Although the exact mechanisms for thisnot are understood, itas speculated, is beenhas also This suggests that MK not suppresses only nucleation but C-S-H, of alsopost-nucleation its growth. Acceptedout Article of [C of particulates’ surfaces is unable to partake innucleation the and growth( process ghreplacement level (i.e., 30% G [C out 3 y an y order of magnitudewith respect to the control paste. This corroborates the hypothesis 3 (t) S + intermediateS + paste, MK] at ). As can). beseen, the trends in S + 8% to ]( C 3 Figure 8 Figure 7B S and MK particulates’ surfaces mass H supersaturationin the solution and MK] [C I Figure 7A section 4.2 density ). This functional form of ) I . density ; ; particulateagglomeration is expected tonegligible be inintermediate the Such largereductions in of [C of

( Fi 3 )and S + 30%S + 3 gure 7B a S + coarseS + pasteMK] , wherein ithypothesizedwas in fine that MK, effects particleof MK mass and . Figure 6 I Th density Figure 7C ), ), a largefraction surface of area fine of (with MK largest the mass e intermediatee MK, in particular, significantly reduces ), 30% N I the values of density

Nuc is reduced by ≈ pastes MK] lower are than those of thecontrol paste passivation particulates’ of surfaces mass with respect to MK replacement levelare remarkably ) and ) subsequentadsorption aluminate of ions onto the , were combined described [as in , thus, blocking potential C-S-H nucleation sites. shows at that low replacement level, the fineand G replacement level of MK out . a Figure 7B Itis noted that, at agesearly has been reported(9,50,64,71) to emulate MK substrates’ surfaces thus blocking potential C and – albeit small N Nuc 1order of magnitude with respect to the I density of all[C of ). Theseresults are in agreement good Figure 7A

Figure 4 are . Thealuminate ions, induetime, 3 attributed exclusivelythe to – S + pastesMK] remain is also attributedsolely to the ly in )extracted directly from , ≈70% theof surface area is ); furthermore,); Figure 6 I density section 3.0 result in significant (i.e., up to ≈12 h) Figure Figure 6 ) results ) in faster – a clear reversala clear Figure 7A ), which I . density ( Notably Eq. 3 N N Nuc is Nuc ) and ) . : )] , -S- ,

This article isprotected rights by All copyright. reserved. replaceC and coarse,with particulatesizes > µm 32 – hydration kinetics of tricalcium silicate(C This study attemptselucidate to the effect particleof distributionsize (PSD) of metakaolin(MK) on the filler effectas does it for other inert fillers (e.g., limestoneand (8,10,49)). quartz (e.g., achieved using grindingdoes methods) lead not proportionalto or monotonic enhancement of contentin the paste.Importantly, this study shows thata mereincreasein SSA particulatesof MK potential to serve a as filler, butmagnitude filler of its effectstrongly is dependent itson and PSD therefore,unable to affect C hydration [C of Overall, the results reported and discussed in such, (50,71,87) values the pasteis Hand, subsequently cut accessoff its to the contiguous solution, thussubduing growth. its When are not surfacesand suppress the post-nucleation growth of C-S- solution)onto C effectcaused is by adsorptionof aluminate ions (released from the dissolution of into MK the [Al(OH) This isdue to effects particulateof agglomeration (especially, fineof inthe case MK) and aluminate theof main hydrationpeak. Athigh replacement level, however,the filler effect of MKreversed. is as enhanced nucleationdensity C-S-H,of resulting infaster kinetics of C particulates of MK are able to exertfiller effect at low replacement level. The filler effect manifests filler effectdepends stronglyon the PSD and content of VeryMK. fine (high SSA) coarseor (lowSSA) C of specificsurface area (SSA) particulateof MK’s resultsThe show tha growth parameters inrelation to the PSD and content inof MK the pastes. experimentally-derived hydration kineticsprofiles, and assess variations in key nucleation and the pastes.A phase boundarynucleation and growth (pBNG)model was applied reproduceto the conjunction with thermogravimetric analyzer (TGA), was usedto monitor kinetics C of replacements [i.e., low (8% 5.0. Acceptedfine, with particulate sizes < 20 µm; intermediate, with particulate sizesbetweenµm 20 Article 3

Conclusions S is nonlinearS is and non-monotonic. is MK ableto exert filler effect,albeit the magnitude of the G out 4 adsorbed onto substrates’ surfaces - ] 3 converges to similar(and low) regardlessvalues thePSDof replacementor level of MK. ion induced surfacepassivation (in both coarseand fineThe MK).surface passivation S in pastes(prepared asconstantliquid- mature(i.e., age≈ 72 h) 3 S + MK] pastes, the pozzolanicactivity is of MK insignificant(see 3 S and MK particulates,whichinhibit C-S- , sucheffects aluminate of ions producton growth rate becomediscernible. less As t – unlike fillers other such limestone as and quartz mass 3 S hydration behavior ina consequential way.MK, however, has the ) and) high (30% , that, is, when the supersaturation of C-S- 3 S) duringthe first 72 hoursafter mixing – during thefew first hours hydration)of adsorb onto C-S- of MKwere used.The additive usedwas to partially s and theconsequent alterationin hydration behavior sections 4.1-4.3 mass )] to were used. Isothermal microcalorimetry, in -solid massratio of 0.45); two different H. H nucleation sites on thesubstrates’

show that within thefirst h of72 3 – S hydration inneighborhood the correlation between H is relegated to low Figure 4 . Three uniqueThree PSDs

3 S hydration in ) , – and,

32 µm;

This article isprotected rights by All copyright. reserved. AcceptedAditya Kumar Hongyan Ma Jonathan Lapeyre ORCID conflict interest.of National ScienceFoundation (NSF, CMMI: and1661609 CMMI: 1761697). authorsThe declare no and Technology (Missouri S&T).Theauthors acknowledgethe financial providedsupport the by This study was conducted inthe Materials Research Center(MRC) Missouri of University Scienceof Acknowledgements Article passivation. are leastsusceptible to effects particulateof agglomerationaluminate and ions-inducedsurface optimal for enhancement of hydration of C replacement level of MK, wherein particulates areof MK predominantly coarse(i.e., lowSSA), are hydration C of surfacearea (or fineness) of MKparticulates doesnot necessarily resultin enhancedearly-age mechanisms of C Overall, outcomes this of work provideinsightsnew into the role particleof size MKof hydration on nucleation sites. ions inthe solution, and, therefore, pronouncedmore inhibition C of dueto faster dissolution kinetics intermediateof MK, which results infasterrelease aluminateof progressively (with respect to the control paste) as thecontent of pasteMKincreases. inthe This is is reversed even at lowreplacement level, and the nucleation density C-S-H is of diminished MK, the filler effectis observed neither atlow nor at high replacement In levels. thefact, filler effect Incase the intermediateof the SSA MK, of which intermediatesbetween those of coarseand fine

https://orcid.org/0000 https://orcid.org/0000 3 S. 3 The results,are which rather counter-intuitive, stronglysuggest lowthat S. the For time, first is it shown that grinding basedimprovementsspecific in https://orcid.org/0000 -

0003- - 0001- - 3674- 0003- 7550- 3845 2562 8034 3 S (i.e.,up to 72 h). This isbecause coarseMK particulates

- 7005

3 S dissolution and C-S- H This article isprotected rights by All copyright. reserved. 5. Worrell E, PriceL, Martin N, Hendriks C, Meida LO. CARBON DIOXIDEEMISSIONS FROM THE 4. MeyerC. greeningThe of theconcrete industry. Cem Compos.Concr 2009 Sep;31(8):601 3. JuengerMCG, Winnefeld F, ProvisIdeker JL, JH. Advances inalternative cementitious binders. 2. Antoni M, Rossen J,Martirena F,Scrivener K. Cement substitution by a combination of 1. References Accepted Berodier Scrivener E, K. UnderstandingFiller the Effect on the Nucleation and Growth of C-S-H. 15. Deschner F,Winnefeld F, Lothenbach B, SeufertS, Schwesig P, Dittrich S,etal. Hydration of 14. LothenbachScrivener B, K, Hooton RD. Supplementary cementitious materials. Cem Concr Res. 13. Gutteridge WA, Dalziel JA. FillerCement: TheEffects ofSecondary the Component on the 12. Gutteridge WA, Dalziel JA. Fillercement: Theeffect ofsecondary the component theon 11. Oey T, Kumar A,Bullard JW, Neithalath N, SantG. The filler effect: The influence fillerof 10. LapeyreJ, Kumar A.Influence pozzolanicof additives onmechanisms hydration of tricalcium 9. A, Kumar Oey FalzoneT, G, Huang J,Bauchy BalonisM, M, al.et filler The effect: influenceThe 8. Article BichAmbroise C, J, Péra J. Influenceof degree dehydroxylationof theon pozzolanic activity of 7. Biernacki JJ, Bullard JW,Sant G, Brown GlasserK, FP, JonesS, et al.Cementsin the21st 6. GartnerE. Industrially interesting approaches to “low GLOBAL CEMENTINDUSTRY. Annu Rev Energy Environ. Nov;26(1):303 2001 Cem Concr Res. 2011;41(12):1232 metakaolin and limestone. Cem Concr Res. 2012;42(12):1579 Sep;34(9):1489– SchererG, editor. JAm Ceram Soc. 2014 Dec;97(12):3764 1400. Portland cementwith high replacement by siliceous fly ash. Cem Concr Res. 2012;42(10):1389 2011;41(12):1244 1990;20(c):853– Hydration of Portland Cement. part Fine2. Non-Hydraulic Filler. Cem Concr Res. 1990;20(6):778 hydration of Portland cement. Part 1: AFinenon-hydraulic binders. Cem Concr Res. 1990. contentand surfacearea on cementitious reaction rates. JAm Ceram Soc. 2013;96(6):1978 silicate. JAm Ceram Soc. 2018 Aug;101(8):3557 2017;100(7):3316 fillerof contentand type onhydration the rate of tricalcium silicate. J Am Ceram Soc. metakaolin. ApplSci. Clay 2009;44(3 73. century: Challenges, perspectives,and opportunities. J Ceram Am Soc. 2017 Jul;100(7):2746 – 861. 98. 782. – – 1256. 1256. 3328. – 1243. – 4):194 – 200. – 74. - CO2” cements. Cem Concr 2004Res. – 73. – 1589. – 29. – 5. – – – 9 Badogiannis E, Kakali G, Tsivilis S 29. 2 Brindley GW,Nakahira M. Kaolinite-MulliteThe Reaction Series: II, Metakaolin. J CeramAm 32. Sabir B,Wild S, Bai J. Metakaolin and calcined clays as pozzolans for concrete: Areview. Cem 31. Shvarzman A, KovlerK, GraderG., Shter G.Theeffect dehydroxylation/amorphizationof 30. 28. Roy D., Arjunan Silsbee P, EffectM. silicaof fume, metakaolin, and low-calcium fly ash o 27. Ramlochan T, Thomas M, GruberKA. The effect of metakaolin alkali on 26. This article isprotected rights by All copyright. reserved. Accepted 25. Shi Z,Lothenbach B, Geiker MR, Kaufmann J,Leemann A,Ferreiroet S, al.Experimental studies 24. HeC,Oscbaek B, Makovicky E. Pozzolanic reactions of six principle clay minerals: Activiation, 23. Article A, Tironi Trezza ScianMA, AN, IrassarEF. Assessment pozzolanicof activity differentof calcined 22. Fernandez R, Martirena F, Scrivener KL. The origin theof pozzolanic activity of calcined clay 21. Shi C,Day RL. Pozzolanic reaction in the presence of chemical activatorsReaction Part II. 20. Shi C,Day RL. Pozzolanic reaction in the presence of chemical activators Part I.Reaction 19. Wild S,Khatib JM. Portlanditeconsumption in metakaolin cementpastes Cemand mortars. 18. Idir R,Cyr M, Tagnit-Hamou A.Pozzolanic properties fine of and coarse color-mixed glass cullet. 17. Meng W, Lunkad P, Kumar A, KhayatK. Influence Silicaof Fume and PCE Dispersant on 16. Optimization kaolinof to metakaolin conversion. J Therm Anal Calorim. 2005;81(2):457 pastes. Cem Concr Res. 2000 Apr;30(4):561 Soc. 1959Soc. Jul;42(7):314 Compos.Concr 2001;23(6):441 degree pozzolanicon activity kaolinite.of Cem Concr 2003Res. Mar;33(3):405 r chemical resistance of concrete. Cem Concr Res. 2001 Dec;31(12):1809 concrete. Cem Concr Res. 2000 Mar;30(3):339 Sep;36(9):1727 Al limestone mortars. Cem Concr Res. 2016 Oct;88:60 and thermodynamic modeling the of carbonation of Portland cement, metakaolin and reactivity assessmentsand technological effects. Cem Res.Concr 1995;25(8):1691 clays. Cem Concr Compos. 2013;37(1):319 2011;41(1):113 minerals: Acomparison between kaolinite,illite and montmorillonite. Cem Concr Res. products and mechanism. Cem Concr Res. 2000;7. kinetics. Cem Concr Res. 2000;8. Res.Concr 1997;27(1):137– Cem Concr Compos. Jan;33(1):192011 Hydration Mechanisms of Cement. J ChemPhys 2016;acs.jpcc.6b08121. C. -Akhras NM. Durability of metakaolin concrete to sulfateattack. Cem Concr Res. 2006 as M as

, Cabrera J. sizePore distribution and degreeof hydration of metakaolin – – 34. 122. – 8. 8. 146. – 454. . Metakaolin as supplementary cementitious material : – 29. 29. – – 327. 9. 9. – 44. – 72. – – silica reaction in 13. 13. – – 16. cement – 1702. – n 462. 48. Kumar A, Kumar Bishnoi S,ScrivenerKL. Modelling early age hydration kinetics of alite. Cem Concr 48. LandStephan G, Controlling D. cement hydration with nanoparticles. Cem Concr Compos. 2015 47. Bellmann F, Ludwig H-M. Analysis aluminumof concentrations in the pore solution during 46. Begarin F,Garrault S,NonatA, Nicoleau HydrationL. ofcontaining alite aluminium. Adv Appl 45. Nicoleau SchreinerL, E, NonatA. Ion-specificeffects influencingdissolution the tricalciumof 44. 43. 42. 41. Taylor-LangeSC, Lamon EL, Riding Juenger KA, CalcinedMCG. kaolinite-bentoniteblends clay 40. AmbroiseJ, Maximilien S, Pera J. Properties of Metakaolin blended cements. Adv Cem Based 39. Panagiotopoulou C,Kontori E, Perraki T, Kakali G. Dissolution of aluminosilicate minerals and 38. Konan KL, PeyratoutC, Smith A,Bonnet JP, Rossignol S, Oyetola S. Comparison of surface 37. Taylor-LangeSC, Riding KA, JuengerMCG. Increasing thereactivity of metakaolin-cement 36. SperinckS, Raiteri P, MarksWright N, K. Dehydroxylation of kaolinite to metakaolin 35. White CE, JL,Provis Proffen Riley T, van DeventerDP, JSJ. Combining density functional theory 34. This article isprotected rights by All copyright. reserved. Accepted Article Brindley GW,Nakahira M. Kaolinite-MulliteThe Reaction Series: III, High-TemperatureThe 33. Res. 2012;42(7):903Res. Mar;57:64 hydration of tricalcium silicate. Cem Concr Res. 2017 May;95:84 Ceram. 2011 Apr;110(3):127 silicate. Cem Concr Res. 2014 May;59:118 Oct;100:245 Influenceof aluminates on the hydration kinetics of tricalcium silicate. Cem Concr Res. 2017 Pustovgar E, Mishra RK, Palacios d’EspinoseM, de Lacaillerie J review. 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JMater Sci. 2007 May 9;42(9):2967 – – 7. 7. – 74. 74. 62. – – 918. – 109. 168. – 30. – 4):392 – 400. – 38. – 24. – 25. – 847. -B, -B, Matschei T, Andreev AS, et al. – 94. – 73. 73. – 93. 93. of concretesof — a 3 Garboczi EJ, Bullard JW.Shapeanalysis ofreference a cement. Cem Concr Res. 63. Bullard JW,Garboczi EJ. A model investigation theof influenceof particleshape portlandon 62. 61. 60. 59. Erdogan ST, Quiroga PN, Fowler DW, Saleh HA, Livingston RA, Garboczi EJ, et al.Three- 58. Pignatelli I, Kumar A,Alizadeh R, Le Pape BauchyY, Sant G. AM, dissolution-precipitation 57. Hamilton A,Hall C. AReviewof Rehydroxylation inFired-Clay Ceramics. J Am Ceram Soc. 2012 56. Standard Guidefor WetSieve Analysis Ceramicof Whiteware Clays. 2014. 55. Lagier F, Kurtis InfluenceKE. of Portland cement composition on early agereactions with 54. Justice JM, Kurtis Influence KE. of Metakaolin Surface Areaon Properties Cement-Based of 53. Givi AN, Rashid SA, Aziz FNA, Salleh MAM. Assessmentof the effects riceof husk ash particle 52. Bentz DP, Garboczi EJ, Haecker CJ, Jensen OM. Effects cement of particle sizedistribution on 51. Ley-Hernandez AM, LapeyreJ, CookR, Kumar A,Feys ElucidatingD. theEffect of Water- 50. This article isprotected rights by All copyright. reserved. Accepted Article A, Kumar Oey KimT, S, Thomas BadranD, S,Li J,et al. Simple methods to estimatethe 49. 2004;34(10):1933 cementhydration. Cem Concr Res. 2006 Jun;36(6):1007 particles. Powder Technol. 2011;207(1):78 realon particle 3D data: improved numerical algorithm and quantitativecomparison to real Liu X, Garboczi EJ, Grigoriu LuM, Y, Erdoğan ST.Spherical harmonic 20–60 μm cement particles. JCeram Am Soc. 2010;93(6):1626– HolzerL, latt RJ,Erdoğan ST, Bullard JW, Garboczi EJ. Shapecomparison betw diffraction particlesize measurement. Cem Concr Res. 2010;40(5):731 eightcements: Particleshape and cement chemistry, andeffect the particleof shape laseron ErdoğanNie ST, X, Stutzman PE, Garboczi EJ. Micrometer 1627. severalon different coarse aggregates and referencerocks. Cem Concr Res. 2006;36(9):1619 dimensional shapeanalysis coarseof aggregates: New techniquesfor and preliminaryresults 2016;145(5):054701. mechanism is at the origin concreteof creep in moist environments. JChem Phys. Sep;95(9):2673– metakaolin. Cem Concr Res. 2007;37(10):1411 Materials. J Mater Civ Eng. Sep;19(9):762 2007 Mater. 2010;24(11):2145 size strength,on waterpermeability and workability of binaryblended concrete. Build Constr 1999;29(10):1663 performance properties of Portland cement-based materials. Cem Concr Res. 105. Cement Ratio on the Hydration Mechanisms Cement.of ACS Omega. 201831;3(5):5092 May Cem Concr Compos. 2013;42:20 influenceof limestonefillers reaction on and property evolution in cementitious materials. 8. 8. – – 1937. 1937. 1671. – 2150. 2150. – 29. – 86. 86. – – 1417. 71. – 15. -scale shape 3-D characterization of 1633. -based random fields based – 739. een 0.4 – 2.0 and To - – – This article isprotected rights by All copyright. reserved. Accepted Lasaga AC, LuttgeA. Variation of crystal dissolution ratebased dissolution a on stepwave 81. Avet F,Scrivener K. Investigation theof calcined kaolinitecontent on the hydration of 80. 79. 78. C-S, Poon Lam L, Kou SC, Wong Wong Y-L, Rate R. pozzolanicof reaction of metakaolin inhigh- 77. Bellmann F, Scherer Analysis GW. CSHof growth rates insupersaturated conditions. Cem Concr 76. NelderJA, Mead R.A Simplex Method for Function Minimization. ComputJ. 1965 Jan 75. A, Kumar Oey FallaT, GP, Henkensiefken R, Neithalath N, SantG. A comparison of intergrinding 74. SchererGW, Bellmann F. Kinetic analysis CSHof growth calcite. on Cem Concr Res. 73. Bazzoni A, S, Ma Wang Shen Q, Cantoni X, ScrivenerM, KL. effectThe of magnesium and zinc 72. Article Bullard JW,SchererGW, Thomas JJ. Timedependent driving forcesand the kineticsof 71. SchererGW, Zhang J, Thomas JJ. Nucleation and growth models for hydration of cement. Cem 70. SchererGW. Models of Confined Growth. Cem Concr 2012;42(9):1252Res. 69. Zhang J,SchererGW. Comparison of methods for arresting hydration cement.of Cem Concr 68. Stoian J,Oey Bullard T, JW, Huang Kumar J, A,Balonis etM, al. Newinsights into the 67. Oey T, Kumar A,FalzoneG, Huang J,Kennison S,Bauchy M, et al.The Influence of Water 66. Taylor HF. Cementchemistry. Thomas Telford; 1997. 65. R, Cook Ma H,Kumar A. Mechanism of tricalcium silicate hydration in the presence of 64. model. Science. 2001;291(5512):2400 LimestoneCalcined Clay Cement (LC3). Cem Concr Res.2018 May 1;107:124 the heat evolution in metakaolin-cement mortars. Cem Concr Res. 2000;30(2):209 r asM, De Rojas CabreraMS, J. The effectthat the pozzolanic reacti review. Appl Clay Sci. 2009;43(3):392 A concrete: and properties mortar of on the Influence J. metakaolin of Klaus R, Siddique performance cement pastes. Cem Concr Res. 2001;31(9):1301 http://www.sciencedirect.com/science/article/pii/S0008884616301739 [Internet].Res 2017; Available from: 1;7(4):308 Build Mater. 2013;43:428 and blending limestone on reaction strength and evolution incementitious materials. Constr 2016;103:226 ions hydration the on kinetics of JAm C3S. Ceram Soc. 2014;97(11):3684 tricalcium silicatehydration. Cem Concr Res. 2015;74:26 Res.Concr 2012;42(7):982– 2011;41(10):1024Res. prehydration of cement and its mitigation. Cem Concr Res. 2015;70:94 Activity theon Hydration Rate Tricalciumof Silicate. J CeramAm Soc. 2016 Jul 1;99(7):2481 polycarboxylate polymers. SN Appl Sci. Jan 2019 3;1(2):145. – 13. – 35. – 1036. – 435. 993. – – 400. 2404. – 34. – 1306. on on of metakaolin has on – 103. – 3693. – 60. – 35. 35. – 216. – 92. 92. This article isprotected rights by All copyright. reserved. dela Varga I, Castro J,Bentz DP, Zunino F, Weiss J. EvaluatingHydration the Highof VolumeFl 84. Bentz DP,Ferraris CF,la De Varga I, Peltz MA, Winpigler JA. Mixture proportioning options for 83. 82. List of Tables Bullard JW.Adetermination hydration of mechanisms for tricalcium silicate usingkinetic a 87. Brown PW, FranzFrohnsdorffE, G, Taylor HFW. Analyses theof aqueous phaseduring early 86. Rojas De MS, Luxan MP, Frías M, GarciaN. influenceThe differentof additions on portland 85.

AcceptedTable 1 Article improving high volumefly ash concretes. IntJ Pavement Res Technol. 2010;3(5):234. Oct 1;100(Supplement C):245 Influenceof aluminates on the hydration kinetics of tricalcium silicate. Cem Concr Res. 2017 Pustovgar E, Mishra RK, Palacios d’EspinoseM, de Lacaillerie J Ash MixturesUsing Chemically Inert Fillers. Cem Concr Compos. 2017;161:221 cellular automaton model. J Ceram Am Soc. 2008;91(7):2088 hydration.C3S Cem Concr 1984;14(2):257Res. cementhydration heat.Cem Concr Res. 1993;23(1):46 : Composition: of metakaolin Loss of IgnitionLoss (LOI) of Na Components 2 O Fe Al MgO TiO SiO CaO equivalent SO # 2 2 O O

3 2 2

3 3

– 62.

, interms of oxides, – 262.

as – 54. determined from x – -B, -B, Matschei T, Andreev AS, et al. 2097. 2097. <0.01 47.80 51.30 % 0.52 0.21 0.90 0.09 0.04 0.44 MK mass

- ray fluorescence – 8. 8. .

y This article isprotected rights by All copyright. reserved. Figure 3 atrate the hydration main is peak ±2%. hydration. The heat flowrates up to 24 hours hydration; of and ThreeMK. different PSDs of MK have been used. ( Figure 2 diameter(d Figure 1 List of Figures given point intimewithin is ±5 solution.such For lowheat evolving systems, theuncertainty in the measured heatflow rateany at (primary y-axis)and cumulative heat release(secondary y-axis) dissolvingof MK in saturatedlime Figure 6: calorimetry profiles,is, that ±2%. acceleration period. uncertaintyThe ineach calorimetric parameterthe is same uncertainty as the in time to the main hydration peak; Figure 5 quantifications by is ±2.5%DTG CH (1:1 molarpaste ratio)] ( C represents the dilution lineproportional (i.e, reductionin inCH relation content to the reduction in the grey area represents theCH content formed in the control paste, and the lowerbound prepared at: ( Figure 4: atrate the hydration main is peak ±2%. hydration. The heat flowrates up to 24 hours hydration; of and ThreeMK. different PSDs of MK have been used. ( 3 AcceptedS content).( Article : Measured calorimetry profiles of [C : Measuredcalorimetry profiles of [C : The PSDs C of : Calorimetric parameters extracted from heatevolution profiles pastes:of Isothermal microcalorimetry based determinations time-dependentof degree reactionof The temporal evolution of CHcontent(expressed dry as fraction)mass in [C 50 , µm) theof powders is theon order ±6%. of A C l/s l/s ) replacement; 8% and ( ) DTGtraces showing differential mass loss,function as temperature,of in[MK a allpastesof is For 0.45. agiven system,uncertainty the inthe measured heat flow allpastesof is 0.45.For agiven system,uncertainty the inthe measured heat flow 3 S andused MK in thisstudy. Thelargest relative uncertainty in median l/s 0.45)= at after 72 h mixing.highestThe uncertainty inphase %. .

(B) heat flow rate at the main hydration peak; and B ) 30% replacement level of C 3 3 S + MK]S + pastes, wherein 30% MK]S + pastes, wherein 8% (C) (C) A A ) Heat) flowrates up to 72 hours hydration; of ) Heat) flowrates up to 72 hours hydration; of cumulative heat release up to 72 hours of cumulative heat release up to 72 hours of 3 S with MK.upper The bound of mass mass of C of C 3 S isreplaced by 3 S isreplaced by (A) (C) 3 S + MK] pastes,MK] S + inverse of slope of the + (B) (B)

uncertaintyno associated with them. [C Figure 8: Simulationsdeterministic, are and, therefore, there is uncertaintyno associated with them. C of This article isprotected rights by All copyright. reserved. ( of MK Figure 7: 3

Accepted Article30%S + 3 S ( N a MK Nuc Simulation output,outward growth rate of the product,in Parametersderived from pBNG simulations [C of mass ); ). Allparameters plotted are against the MKreplacement level (% (B) M product nucleation density ( K] pastes as function of Simulationstime. are deterministic,and, therefore, there is

I density ); and); (C) 3 total number productof nuclei per gram S + pastes:MK] (A)

[C 3 S + (A) mass reactive area fraction 8% ) inpastes. the mass M K] ; and; (B)

This article isprotected rights by All copyright. reserved. Accepted Article