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Scien i ic RepoR S | (2018) 8:8544 | DOI:10.1038/s41598-018-26943-y
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Mul iscale unde s anding o
icalcium silica e hyd a ion
eac ions
Ana Cues a1,2, Jesus D. Zea-Ga cia2, Diana Londono-Zuluaga2, Angeles G. De la To e2,
Isabel San ac uz2, O iol Vallco ba
1, Monica Dapiaggi3, Susana G. San élix2,4 &
Miguel A. G. A anda
1
T icalcium silica e, he main cons i uen o Po land cemen , hyd a es o p oduce c ys alline calcium
hyd oxide and calcium-silica e-hyd a es (C-S-H) nanoc ys alline gel. This hyd a ion eac ion is poo ly
unde s ood a he nanoscale. The unde s anding o a omic a angemen in nanoc ys alline phases is
in insically complica ed and his challenge is exace ba ed by he p esence o addi ional c ys alline
phase(s). He e, we use calo ime y and synch o on X- ay powde di ac ion o quan i a i ely ollow
icalcium silica e hyd a ion p ocess: i) i s dissolu ion, ii) po landi e c ys alliza ion and iii) C-S-H
gel p ecipi a ion. Chie ly, synch o on pai dis ibu ion unc ion (PDF) allows o iden i y a de ec i e
clino obe mo i e, Ca11Si9O28(OH)2.8.5H2O, as he nanoc ys alline componen o C-S-H. Fu he mo e,
PDF analysis also indica es ha C-S-H gel con ains monolaye calcium hyd oxide which is s e ched
as ecen ly p edic ed by i s p inciples calcula ions. These ou comes, plus addi ional labo a o y
cha ac e iza ion, yielded a mul iscale pic u e o C-S-H nanocomposi e gel which explains he obse ed
densi ies and Ca/Si a omic a ios a he nano- and meso- scales.
Le Châ elie 1 al eady es ablished ha Po land cemen hyd a ion s a s by he dissolu ion o calcium silica e
species in wa e om he mos soluble silica e phase. This p ocess is ollowed by he p ecipi a ion o complex
poo ly-c ys alline calcium-silica e-hyd a es (gene ically named C-S-H gel) and he c ys alliza ion o Ca(OH)2,
po landi e, see o e all eac ion (1)2. C-S-H gel is he main hyd a ed componen in Po land cemen pas es,
and i is he main esponsible o he s eng h and du abili y o he esul ing mo a s and conc e es. Ali e, an
impu e o m o icalcium silica e Ca3SiO5, is he main phase p esen in Po land cemen s and i has a sligh ly
a iable composi ion due o elemen -subs i u ions2. The hyd a ion o any ali e shows, in addi ion o an ini ial
as (mino ) dissolu ion, h ee main s ages wi h ime: i) induc ion (also known as do man pe iod), ii) accele a-
ion; and iii) decele a ion3. Simila kine ic p o iles ake place in a ious he e ogeneous hyd a ion p ocesses, o
ins ance mine al wea he ing4 and glass al e a ion5. The e a e wo main heo ies o explain his ea ly-age hyd a-
ion beha iou . The i s is known as ‘p o ec i e laye ’ and i consis s in he p ecipi a ion o a C-S-H gel di usion
ba ie on he su aces o ali e pa icles which densi y and adhe ence change wi h ime. The second is known as
‘geochemical model’ and i is ela ed o he ali e dissolu ion mechanism e ol ing om e ch pi o ma ion o s ep
e ea 6. Despi e one cen u y o ocused in es iga ions, he unde lying mechanism(s) o such ime e olu ion is
s ill s ongly deba ed7,8.
+. →. +..
Ca SiO52H O12Ca(OH)(CaO) SiO(HO)(1)
35 2218 2240
The hyd a ion eac ions o ali e, (i) dissolu ion o c ys alline ali e, (ii) p ecipi a ion o C-S-H gel, and (iii) c ys-
alliza ion o po landi e, ha e been ho oughly s udied by many echniques including labo a o y X- ay pow-
de di ac ion9–12, calo ime y13–15, small-angle neu on sca e ing16; ad anced elec on mic oscopies17,18, 29Si
magic-angle-spinning nuclea -magne ic- esonance19,20, and heo e ical simula ions21–23. C-S-H gel has a nano-
c ys alline na u e and so i s unde s anding is e y challenging24 which includes he ela ionship wi h he solu ion
1ALBA Synch o on, Ca e de la Llum 2-26. 08290 Ce danyola del Vallès, Ba celona, Spain. 2Depa amen o de
Química Ino gánica, C is alog a ía y Mine alogía. Uni e sidad de Málaga, 29071, Málaga, Spain. 3Depa men o
Ea h Sciences “A di o Desio”, Uni e si y o Milan, Milano, I aly. 4Facul y o Enginee ing, Øs old Uni e si y College,
N-1757, Halden, No way. Co espondence and eques s o ma e ials should be add essed o M.A.G.A. (email:
[email p o ec ed])
Recei ed: 12 Feb ua y 2018
Accep ed: 14 May 2018
Published: xx xx xxxx
OPEN
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Scien i ic RepoR S | (2018) 8:8544 | DOI:10.1038/s41598-018-26943-y
whe e i is equilib a ed25. The e a e many e iews add essing his componen and we ci e jus he mos ele an
and ecen ones26–28. An upda ed mechanism o g ow h o C-S-H gel has been e y ecen ly p oposed29. I is also
impo an o add ha he hyd a ion o ali e is a ec ed by he p esence o o he species. This has been e y ecen ly
exempli ied by he s udy o he in luence o alumina es, added as NaAlO2, on he hyd a ion kine ics o ali e which
was s udied by a mul i echnique app oach including molecula dynamics simula ions o in es iga e he dissolu-
ion s ep a he nanoscale30.
Many s udies ha e shown ha he C-S-H gel agg ega es con ain poo ly-c ys alline in e connec ed nano-
pa icles desc ibed as globules, disks and oils31–36 which enclose wa e wi hin nanopo es, known as gel po e
wa e 26. This gel wa e can e ol e wi h ime wi h consequences in C-S-H ‘bulk’ densi y37. I is wo h no ing ha
his wa e wi hin he gel is di e en om he capilla y po e wa e (also known as ee wa e , FW) as i can-
no be emo ed wi hou al e ing he p ope ies o he sys em27. Conce ning he a omic a angemen wi hin he
nanoc ys alline componen o he C-S-H gel agg ega es, se e al expe imen al and heo e ical echniques ha e
concluded ha de ec i e clino obe mo i e is he bes a ailable app oxima ion37–40. C ys alline obe mo i e-14Å,
Ca5Si6O16(OH)2.7H2O, has a Ca/Si a io and densi y o 0.83 and 2.19 gcm−3, espec i ely. The co esponding
alues o c ys alline obe mo i e-11Å, Ca4Si6O15(OH)2.5H2O, a e 0.67 and 2.40 gcm−3, espec i ely41. These p e-
ious obse a ions a e s iking as hey a e no in s aigh o wa d ag eemen wi h wo well-es ablished key bulk
measu ed p ope ies: i) he Ca/Si a io on he C-S-H agg ega es anges be ween 1.6–2.0; and ii) he densi y o
nanoglobules (gel po e wa e excluded) ange 2.5–2.6 g·cm−3 2,31,37. De ec i e clino obe mo i e could jus i y a
Ca/Si a omic a io close o 1.2–1.3, bu no highe han ha 42. Ve y ine in e mixing o C-S-H gel wi h calcium
hyd oxide has been p oposed om elec on mic oscopy43,44 which i could explain an o e all Ca/Si a io anging
1.6–2.0.
The aim o his wo k is o con ibu e o he unde s anding o bo h he o ma ion and nanos uc u e o C-S-H
gel. Fi s ly, we used synch o on X- ay powde di ac ion (and calo ime y) o in si u de e mining he dis-
solu ion o ali e as well as he c ys alliza ion o po landi e and he p ecipi a ion o he gel. Secondly, we ha e
employed synch o on X- ay o al sca e ing (and 29Si MAS-NMR) o s udy he sho - and medium- ange a omic
a angemen in he C-S-H gel nanopa icles. Wi h his knowledge and obse a ions om elec on mic oscopy
and p e ious epo s, we p opose a model o his complex he e ogeneous sys em, de eloping a mul iscale pic u e
(see Fig.1) o he hyd a ion o ali e in o de o explain he obse ed mass densi ies and Ca/Si a omic a ios a he
di e en scales. A he nanoscale, below 10 nm, C-S-H gel a e composed o a ine in e mixing o de ec i e clino o-
be mo i e, pa icle sizes anging 3–5 nm wi h Ca/Si a io close 1.2, and monolaye s o Ca(OH)2. These agg ega es
gene a e he gel po es. A he mesoscale, be ween 10 and 100 nm, nea C-S-H gel appea s ela i ely he e ogene-
ous wi h (CaO)1.8SiO2(H2O)4.0 o e all composi ion bu sligh ly a iable Ca/Si a omic a ios in di e en olumes.
This is now explained by sligh ly di e en de ec i e clino obe mo i e o Ca(OH)2-monolaye s local a ios. A he
mic oscale, abo e 100 nm, he hyd a ion eac ion o ali e is well known esul ing in c ys alline Ca(OH)2, also
named po landi e, C-S-H gel and capilla y wa e , see Fig.1.
Resul s
In si u calo ime ic s udy. The hyd a ion eac ions o icalcium silica e we e s udied in si u by calo ime y
and synch o on X- ay powde di ac ion (SXRPD). The pa icle size dis ibu ion (PSD) (diame e ) o as- e-
cei ed ali e was qui e la ge, D ,50 = 20.8 µm, see Supplemen a y Fig.1a. The e o e, wo addi ional samples we e
p epa ed, see me hods, wi h D ,50 = 7.4 and 2.7 µm, Supplemen a y Fig.1b,c, espec i ely. The alues o D ,10 and
D ,90 a e also shown in Supplemen a y Fig.1. The cha ac e iza ion o hese h ee ali es is gi en in he supplemen-
a y in o ma ion. Hea low calo ime y cu es and cumula i e hea eleased aces up o se en days a e shown
in Fig.2a,b, espec i ely. Table1 epo s he key alues ob ained om he calo ime ic s udy including he ali e
eac ion deg ee ha can be es ima ed as he o e all hea o hyd a ion o icalcium silica e is known2, 517 Jg−1.
This is an app oxima ion as he impu i ies in ali e can play a ole as well as he s uc u al de ec s. The ou s udied
pas es a e labelled as C3S_21 µm_045, C3S_21 µm_080, C3S_7 µm_080 and C3S_3 µm_080 o highligh hei PSDs
and wa e - o-ali e mass a ios, i.e. 045 means a a io o 0.45. C3S_21 µm_080_qz and C3S_21 µm_080_qz s ands
o samples wi h 10 w % o qua z and hei calo ime ies we e eco ded o he sake o compa ison wi h he
SXRPD s udy whe e 10 w % o qua z as in e nal s anda d was employed.
In si u synch o on X- ay powde di ac ion s udy. SXRPD da a aken in capilla ies o unal e ed
pas es we e analyzed by Rie eld me hodology employing he in e nal s anda d me hod, in his case qua z, o
amo phous quan i ica ion45. Fo his in si u s udy, he o e all amo phous alues encompass no only he C-S-H
gel con en bu also he FW because he hyd a ion eac ions we e no a es ed. To a i s app oxima ion, he
bound wa e ( he c ys alliza ion wa e and he gel po e wa e ) can be calcula ed acco ding o eac ion (1), as he
amoun o dissol ed ali e is known. Then, his calcula ed alue is sub ac ed om he ini ial amoun o wa e , in
o de o ob ain he amoun o FW o each hyd a ion age. Finally, all he weigh pe cen ages we e ecalcula ed
excluding he amoun o FW in o de o ollow he e olu ion o he C-S-H gel componen , which i includes he
nanopo e gel wa e and any amo phous calcium hyd oxide.
Figu e3a shows he phase con en e olu ion wi h ime o C3S_21 µm_080 pas e om SXRPD da a. I is
wo h no ing ha , a 5 hou s o hyd a ion (which was ou i s measu emen ), ali e was pa ly dissol ed, ≈4 w %,
and ≈4 w % o C-S-H gel had p ecipi a ed. The c ys alliza ion o po landi e s a ed la e , close o 7.5 hou s. A
14 hou s, only 2.8 w % o c ys alline po landi e was measu ed. The hyd a ion eac ion p og essed slowly up o
100 days o hyd a ion as i can be shown in Fig.3a. As an example, Supplemen a y Fig.2a shows he Rie eld plo
o his pas e a 14 hou s o hyd a ion. Finally, he quan i a i e phase analysis esul s ob ained a 100 days (2400 h)
was 11.8, 22.7 and 62.1 w % o un eac ed ali e, c ys alline po landi e and C-S-H gel, espec i ely. The emaining
con en , 3.4 w %, was beli e, Ca2SiO4.
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Figu e3b shows a simila s udy o C3S_7 µm_080. Fo his sample, he hyd a ion kine ics is as e . A he i s
measu emen ime, 2 hou s, 4.6 w % o ali e was al eady dissol ed, wi h he p ecipi a ion o ≈4 w % o C-S-H gel
and he c ys alliza ion o ≈0.4 w % o po landi e. A 14 hou s, 10.4 w % o c ys alline po landi e was measu ed.
Supplemen a y Fig.2b shows he Rie eld plo o his pas e a 14 hou s o hyd a ion. A ansi ion om he
accele a ed hyd a ion eac ion kine ics o decele a ed kine ics is clea ly obse ed in he phase con en e olu ions
close o 20 hou s o hyd a ion. A 100 days o hyd a ion, 9.3 w % o un eac ed ali e was measu ed coexis ing wi h
25.3 w % o po landi e and 62.8 w % o C-S-H gel. The emaining con en , 2.6 w % was beli e, Ca2SiO4.
29Si MAS-NMR and elec on mic oscopy s udies. The ali e sample wi h he smalles PSD, see
Supplemen a y Fig.1c, was hyd a ed in o de o minimize he amoun o un eac ed ali e. The hyd a ion was
a es ed, see me hods sec ion, in o de o emo e he FW, and his pas e is labelled he ea e C3S_3 μm_080_
a es ed:16d. Rie eld quan i a i e phase analysis o LXRPD a e 16 days o hyd a ion, see Supplemen a y Fig.3a,
ga e: 1.1 w % o un eac ed ali e, 20.5 w % o c ys alline po landi e, 2.5 w % o c ys alline calcium ca bona e
and 75.9 w % o amo phous con en (mainly bu no necessa ily only C-S-H gel). Supplemen a y Fig.3b shows
he simula ed X- ay di ac ion pa e n o he de ec i e clino obe mo i e T3_14sc s uc u e, a e age pa icle
size ≈5 nm, which has been used in he PDF s udy o i he con ibu ion o he nanoc ys alline C-S-H gel.
C3S_3 μm_080_a es ed:16 d was also s udied by 29Si MAS-NMR, see Fig.4, compa ed o ela ed samples in
Supplemen a y Fig.4, and elec on mic oscopy, see Supplemen a y Figs5 and 6. 29Si MAS-NMR da a gi e di ec
in o ma ion abou he silica e chains in C-S-H gel. The signals obse ed a −78.7 and −84.4 ppm we e a ib-
u ed o he Q1 and Q2 Si uni s, espec i ely46,47. Q1 is associa ed wi h silica e end chain uni s and Q2 indica es
he p esence o silica e in in e media e chain posi ions48,49. The e y weak signal a −72.4 ppm co esponds o
Figu e 1. Schema ic unde s anding o he ali e hyd a ion eac ion a di e en leng h scales. (Top) Hyd a ion
eac ion o icalcium silica e a he mic oscale. (a1) SEM mic opho og aph o C3S_21 µm. (a2) SEM
mic opho og aph o C3S_3 µm. (b) SEM mic opho og aph o C3S_21 µm_080 pas e showing a homogeneous
po landi e pla e mic opa icle, oids a ising om capilla y wa e , and h ee agglome a es o he e ogeneous
C-S-H gel. (c) Enla ged iew o one C-S-H gel egion in (b). (d) TEM mic opho og aph o C3S_3 µm_080_
a es ed:16d showing in e spe sed oil-like C-S-H nanopa icles a he mesoscale. (e) Schema ic ep esen a ion
o he C-S-H colloidal nanopa icles o clino obe mo i e (blue) and monolaye Ca(OH)2 (o ange) gene a ing
he small gel po es (SGP) and la ge gel po es (LGP) o Jennings’s model (25). ( ) Schema ic ep esen a ion o
a single C-S-H nanoglobule composed by de ec i e clino obe mo i e and wo monolaye s o Ca(OH)2 a he
nanoscale. (Bo om) Hyd a ion eac ion o icalcium silica e a he nanoscale highligh ing he h ee main
componen s o colloidal C-S-H nanocomposi e: nanoc ys alline clino obe mo i e, amo phous (monolaye )
calcium hyd oxide and gel po e wa e . The (app oxima e) densi ies, mass and olume pe cen ages o he
di e en componen s a e also gi en o an o e all wa e con en o ou wa e molecules pe silica e.
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isola ed Q0 e ahed a om un eac ed ali e. The silica e MCL (mean chain leng h) can be de e mined om he
exp ession48, MCL = 2(Q1 + Q2)/Q1. The decon olu ion o he spec um shown in Fig.4 ga e 70.8% o Q1 and
24.7% o Q2. The e o e, MCL was 2.70. This alue ag eed well wi h p e ious epo s o ea ly age pas es48,49. The
29Si MAS-NMR spec a o wo ela ed samples ga e e y simila MCL alues, see Supplemen a y Fig.4. In addi-
ion, he de e mina ion o he a e age Ca/Si a io is also an impo an pa ame e in any in es iga ion o a C-S-H
gel. Supplemen a y Fig.5 shows a HRTEM mic og aph wi h EDS da a as an example. F om 64 analysed poin s,
he a e age Ca/Si a omic a io was 1.75 ± 0.16. Supplemen a y Fig.6 displays a FEGSEM mic og aph ( ac u e
c oss-sec ion).
To al-sca e ing pai dis ibu ion unc ion s udy. The PDF da a o C3S_3 μm_080_a es ed:16d,
see Fig.5, ha e been analyzed using he same s a egy p e iously epo ed by us40. Ini ially, a high - egion, i.e.
Figu e 2. Calo ime ic da a. (a) Hea low calo ime y cu es and (b) Cumula i e hea eleased o
C3S_21 µm_045, C3S_21 µm_080, C3S_7 µm_080, C3S_3 µm_080, C3S_21 µm_080_qz, and C3S_7 µm_080_qz.
Da a collec ed in he same un o a Po land cemen ype-I (OPC_045 and OPC_080) and OPC_080_qz a e
gi en as e e ence.
Sample BET su ace
a ea (m2/g) (h)1Hea -1 (J/g
cemen )2α-1
(%)3Hea -2 (J/g
cemen )4α-2
(%)5
C3S_21 µm_045 0.3(1) 33 43.2 8.4 214.2 41.4
C3S_21 µm_080 0.3(1) 32 46.1 8.9 219.9 42.5
C3S_21 µm_080_qz — 23 55.4 10.7 286.3 55.4
C3S_7 µm_080 1.1(1) 19 88.4 17.1 353.2 68.3
C3S_7 µm_080_qz — 20 106.1 20.5 404.9 78.3
C3S_3 µm_080 5.2(1) 12 209.1 40.4 451.2 87.3
Table 1. Key alues ob ained om he ali e calo ime ies. 1Time a he maximum o he hea low cu es. 2To al
hea e ol ed a he maximum o hea low cu es. 3Reac ion deg ee a he maximum o hea low cu es. 4To al
hea e ol ed a se en days. 5Reac ion deg ee a se en days.
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Scien i ic RepoR S | (2018) 8:8544 | DOI:10.1038/s41598-018-26943-y
Figu e 3. Quan i a i e phase analysis esul s om SXRPD. (a) C3S_21 µm_080 and (b) C3S_7 µm_080. The
lines o C-S-H gel (blue) and po landi e (g een) show he heo e ical amoun s expec ed om he measu ed
dissolu ion o ali e acco ding o eac ion (1).
Figu e 4. 29Si MAS-NMR spec a o C3S_3 µm_080_a es ed:16d measu ed. Spinning a e o 15 kHz and a
magne ic ield o 14.1 T.

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40–70 Å, was analyzed wi h he con ibu ions o he c ys alline phases: po landi e and ali e. The low amoun o
ali e was compu ed as discussed in he supplemen a y in o ma ion. The calci e con en con e ged o ze o. A e
e ining all pa ame e s, he inal RW alue was 26.9%. The i is displayed in Fig.5a. The uni cell alues o po -
landi e con e ged o a = 3.595 Å and c = 4.918 Å. Secondly, all he p e iously de e mined pa ame e s we e kep
ixed and he con ibu ion om he nanoc ys alline componen o C-S-H gel was in es iga ed in he - egion,
om 10 o 25 Å. As i was p e iously epo ed40, se e al c ys al s uc u es ha e been es ed (Hilleb andi e, Jenni e,
s oichiome ic Tobe mo i e-14, s oichiome ic Tobe mo i es-11 (monoclinic and o ho hombic), s oichiome ic
clino obe mo i es, and selec ed s uc u al desc ip ions om e .42 which had a MCL close o 3.0) o i he con-
ibu ion o he nanoc ys alline C-S-H gel, see Supplemen a y Table1. Jenni e s uc u e led o he wo s PDF i
as e idenced by i s highe RW alue, see Supplemen a y Fig.7. Hilleb andi e has now been included as i has been
e y ecen ly epo ed as a good model o he nanoc ys alline componen o C-S-H gel50 bu i ga e a poo i
o ou PDF da a. Supplemen a y Table1 gi es he RW alues o each PDF i and he quan i a i e phase analysis
esul s. The de ec i e clino obe mo i e s uc u e, T3_14sc42 wi h Ca11Si9O28(OH)2·8.5H2O composi ion, has been
selec ed as i ga e he bes i o he C-S-H gel nanopa icle con ibu ion o he PDF p o ile. The uni cell alues
o he de ec i e clino obe mo i e T3_14sc s uc u e con e ged o a = 11.255 Å, b = 7.320 Å, c = 42.415 Å and
β = 94.2° and he iso opic ADPs we e 0.0083 and 0.0160 Å2 o Ca, Si, espec i ely. The RW was 27.7% and he
inal i is displayed in Fig.5b. Fo all he PDF i s, he ADP (U- he mal displacemen pa ame e ) alue o O was
no e ined, he alue was ixed o 0.070 Å2 wi h co espond o ha o as ecei ed Ca3SiO5. The PDF i ga e he
ollowing quan i a i e phase analysis esul s: 2.2 w % o anhyd ous ali e, 33.5 w % o po landi e and 64.3 w % o
clino obe mo i e.
Thi dly, he low - egion, 2 o 10 Å, was s udied. The PDF i based on he con ibu ions o po landi e, ali e
and de ec i e clino obe mo i e esul ed in a di e ence PDF cu e, which was qui e la ge, see Supplemen a y
Fig.8, especially in he e y low - egion, sugges ing an amo phous componen . The sca e ing mis i closely co -
esponds o he heo e ical PDF ace o an isola ed monolaye o Ca(OH)2 as ecen ly sugges ed39,40. The e o e,
we ha e included a monolaye o Ca(OH)2, a oms a anged as in po landi e, in he PDF i s, see supplemen-
a y in o ma ion. The i o he di e ence cu e indica es ha his monolaye Ca(OH)2 is expanded along a
and c di ec ions, 3.8 and 5.3%, espec i ely and comp essed along b di ec ion, 2.1%. O e all, he olume o
Figu e 5. PDF e inemen s. Expe imen al (blue ci cles), i ed ( ed lines) and di e ence (g ey lines) PDF
pa e ns o C3S_3 µm_080_a es ed:16d (a) om 40 o 70 Å; (b) om 10 o 25 Å; and (c) om 2 o 10 Å. Fo
de ails o he i s, he eade s a e e e ed o he ex .
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monolaye Ca(OH)2 is expanded 7.0% when compa ed o he olume o c ys alline po landi e. This olume
expansion would lead o a densi y dec ease om 2.24 gcm−3 in bulk po landi e o 2.11 gcm−3 in monolaye
po landi e. The s e ched monolaye po landi e s uc u e was hen used in he PDF e inemen (Fig.5c). As
expec ed, he la ge co ela ion in his e inemen ook place be ween he scale ac o s o monolaye -Ca(OH)2
and c ys alline-Ca(OH)2, −55%. The Rw alue o he inal i , wi hou compu ing ali e, see Fig.5c, d opped om
57 o 38% due o he con ibu ion o monolaye po landi e.
Discussion
The hyd a ion kine ic o as ecei ed ali e was slow wi h he maximum in he hea low cu e close o 30 hou s,
wi h a eac ion deg ee o ∼9%, see Table1 and Fig.2. The p esence o 10 w % o c ys alline qua z accele a es
he hyd a ion and he maximum akes place a 23 hou s, wi h a eac ion deg ee o 10.7% o he pas e hyd a ed
a a w/s = 0.80. This slow kine ics was due o he la ge a e age pa icle size, ≈20 μm, and i s ela i ely high i on
con en , 1.1 w % exp essed as Fe2O3. I is known ha i on51 and ch omium52 s ongly delay ali e hyd a ion.
Con e sely, i s kine ic is only sligh ly dependen on he wa e - o-ali e a io as p e iously epo ed14,53. The calo-
ime ic and SXRPD s udies showed a s ong accele a ion o ali e hyd a ion o smalle pa icle size samples, see
Table1 and Figs2 and 3, in ag eemen wi h p e ious epo s11,54. I is wo h no ing ha he small peak e iden
in he hea low cu e a 5 h o C3S_7 µm_080, see Fig.2, is e y likely due o i s bimodal PSD wi h a minimal
ac ion o e y small pa icle size close o 0.6 μm, see Supplemen a y Fig.1b. The accele a ion due o he p esence
o qua z, known as ‘ ille e ec ’55, is much mo e p onounced o he ali e sample wi h he la ges pa icles. This
obse a ion poin owa ds ha ali e dissolu ion is kine ically he limi ing eac ion.
We unde line ha he i s 45 minu es o hyd a ion is no eco ded in ou calo ime ic s udy and his could
neglec he measu emen o he hyd a ion o ≈5% o ali e, acco ding o he esul s om he SXRPD s udy. In any
case is wo h compa ing he eac ion deg ees om calo ime y (wi h qua z!), Table1, and hose ob ained om
he quan i a i e analysis o SXRPD da a, Fig.3. Fo C3S_21 µm_080_qz a 23 h ( he ime o he maximum o he
hea low cu e), a eac ion deg ee (as de ined by he ans o med ac ion) o 11% (i could be ≈16% aking in o
accoun he as dissolu ion) is ob ained om he calo ime ic s udy and ≈19% is ob ained om he synch o on
s udy. Fo C3S_7 µm_080_qz a 20 h, a eac ion deg ee o 21% (which i could be ≈26%) is ob ained om he
calo ime ic s udy and ≈38% is ob ained om he synch o on s udy. We jus i y his disag eemen due o he
main di e ences be ween he wo se o expe imen s: i) he o a ion o he capilla y in he di ac ion s udy wi h
i s associa ed shea e ec ;15 and ii) and he sligh ly highe empe a u e o he di ac ion s udy when compa ed o
he calo ime ic s udy, see me hods. I is key o compa e esul s om di e en echniques bu i is also impo an
o unde s and he ole o he di e en expe imen al condi ions ha some imes a e necessa y o ensu e he max-
imum a ainable accu acy.
I has been epo ed om in si u labo a o y powde di ac ion da a, B agg-B en ano geome y, ha he c ys-
alline po landi e con en was abou one hi d smalle han ha expec ed om ali e dissolu ion acco ding o
eac ion (1)10,56. This is no he case in ou synch o on powde di ac ion s udy as he used me hodology ( o a -
ing he capilla y in ansmission and me ging da a om h ee capilla y posi ions), imp o es he accu acy o he
analyses. Figu e3 also displays he expec ed amoun s o po landi e and C-S-H gel om ali e dissolu ion which
we e in e y good ag eemen wi h he measu ed alues. Finally, i is wo h no ing ha a e y ea ly hyd a ion
ages, he measu ed c ys alline po landi e con en s a e sligh ly smalle han he expec ed ones. We specula e ha
his could be due o he ini ial p ecipi a ion o amo phous calcium hyd oxide.
A 100 days, he RQPA esul s o C3S_21 µm_080 we e 11.8, 22.7 and 62.1 w % o un eac ed ali e, c ys al-
line po landi e and C-S-H gel, espec i ely. The co esponding alues o C3S_7 µm_080 we e 9.3, 25.3 and
62.8 w %, espec i ely. Acco ding o equa ion (1), he expec ed amoun s o po landi e and C-S-H gel we e 23.4
and 61.4 w %, and 24.4 and 63.7 w %, o C3S_21 µm_080 and C3S_7 µm_080, espec i ely. The good ag eemen
be ween he de e mined and expec ed con en s, o bo h samples, indica es he accu acy o he me hodology and
he sui abili y o he s oichiome ic coe icien s in eac ion (1).
The PDF analysis o he o al sca e ing da a o C3S_3 μm_080_a es ed:16d pas e ag ees well wi h ou p e-
ious epo 40. Mo eo e , he e y small amoun o un eac ed ali e, lowe han 2 w %, yielded a PDF s udy wi h
less unce ain ies. The c ys al s uc u e which ga e he bes i o he PDF da a in he egion 10 o 25 Å was
in a iably clino obe mo i e, see Supplemen a y Table1. We ha e selec ed de ec i e clino obe mo i e T3_14sc,
Ca11Si9O28(OH)2·8.5H2O, because in addi ion o he e y good i his app oxima e s uc u e ep esen s a ‘ ime ’
de i ed om a s agge ed-chain clino obe mo i e42. Mo e s udies a e needed o con i m i his s uc u al desc ip-
ion is he bes op ion o he hyd a ion o ali e unde di e en condi ions and in Po land cemen s. I s a e age
silica e chain leng h o 3.0 is in ag eemen wi h he MCL alue, 2.7, ob ained by 29Si MAS-NMR. Howe e , i s Ca/
Si a io, 1.22, does no ag ee wi h he Ca/Si a io o he C-S-H de e mined by elec on mic oscopy, 1.75, which is
widely epo ed in bibliog aphy2,44 and p e iously con i med by eac ion (1). Howe e , hese Ca/Si a ios a e no
ob ained a he same p obing leng h scales. The Ca/Si a io o de ec i e clino obe mo i e measu ed by PDF analy-
sis is ob ained a he nanoscale, p obing scale: 1–3 nm. The Ca/Si a io measu ed by HAADF-STEM is ob ained a
he mesoscale, p obing scale ≈50–100 nm. The Ca/Si a ios de e mined om FEGSEM and Rie eld e inemen
o SXRPD da a a e ob ained a he mic oscale, p obing scale >500 nm. The appa en disag eemen in he Ca/Si
a ios can be econcilia ed by he hypo hesis ha C-S-H gel agg ega es a ising om he hyd a ion o ali e, is a
composi e o med by a ine in e mixing a he nanoscale o de ec i e clino obe mo i e nanoglobules, sizes ≈4 nm,
and amo phous Ca(OH)2, size <2 nm, see Fig.1.
The o e all mul iscale pic u e o he hyd a ion o ali e is shown in Fig.1 whe e eac ion (1) a he mic oscale
is depic ed on op and i s b eakdown a he nanoscale is depic ed a he bo om. The densi ies o he di e en
componen s a e also epo ed as well as hei pe cen ages (mass and olume). The hypo hesis o exis ence o mon-
olaye Ca(OH)2 and i s ine in e mixing wi h de ec i e clino obe mo i e is suppo ed in h ee ways. I. The PDF
analysis in he 2–10 Å egion imp o es no ably wi h he inclusion o monolaye po landi e, RW dec eases om 57
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Scien i ic RepoR S | (2018) 8:8544 | DOI:10.1038/s41598-018-26943-y
o 38%. Un o una ely, he analysis o he scales ac o s does no allow o ob ain he weigh pe cen age o he mon-
olaye Ca(OH)2 componen . II. The de e mined expansion o monolaye Ca(OH)2 in his s udy, 7.0%, is in ag ee-
men wi h he expansion ecen ly p edic ed by i s p inciples calcula ions when s udying pu e calcium hyd oxide
sys ems57. This densi y unc ional heo y heo e ical wo k epo ed he s abili y o monolaye Ca(OH)2 and an
expansion o he a e age Ca-O bond om 2.36 o 2.38 Å om c ys alline po landi e o monolaye Ca(OH)2. III.
The PDF analysis in he 10–25 Å leng h scale ga e c ys alline po landi e and nanoc ys alline clino obe mo i e
con en s o 33.5 and 64.3 w %, espec i ely (see Supplemen a y Table1). Ou model epo ed a he bo om o
Fig.1, and escaled o ake in o accoun 2 w % o un eac ed ali e, gi es 36.8 and 61.1 w %, espec i ely. The ela-
i e close ag eemen be ween hese wo se s o alues can be also in e p e ed as an indi ec suppo o he model.
Conclusion
The in si u SXRPD s udy has con i med he s oichiome y o ali e hyd a ion eac ion o yield po landi e and
C-S-H gel wi h (CaO)1.8SiO2(H2O)4.0 a e age composi ion. Chie ly, by using high- esolu ion synch o on PDF
analysis, i has been ound ha C-S-H gel is he e ogeneous a he nanoscale being composed o de ec i e clino-
obe mo i e, wi h app oxima e composi ion Ca11Si9O28(OH)2·8.5H2O, and monolaye s o Ca(OH)2. Wi h hese
esul s and obse a ions om elec on mic oscopy and p e ious epo s, a mul iscale model o he hyd a ion o
ali e is p oposed (see Fig.1) which explains he obse ed mass densi ies and Ca/Si a omic a ios a he ele an
scales. A he nanoscale, below 10 nm, C-S-H gel a e composed o a ine in e mixing o de ec i e clino obe mo i e,
pa icle sizes anging 3–5 nm wi h Ca/Si a io close 1.2 and ρ≈2.5 gcm−3, and monolaye s o Ca(OH)2, ρ≈2.1
gcm−3. The calcium silica e componen jus i ies he p e iously epo ed nanoglobules densi y, ρ≈2.6 gcm−331,37.
These agg ega es gene a e he gel po es. A he mesoscale, be ween 10 and 100 nm, nea C-S-H gel appea s wi h
a iable composi ions, Si/Ca a io and wa e con en , cen ed a (CaO)1.8SiO2(H2O)4.0. This is explained by sligh ly
di e en de ec i e clino obe mo i e o Ca(OH)2-monolaye s local a ios and he a iable gel po e wa e . Une en
wa e con en also jus i ies he obse ed C-S-H gel densi ies a his scale, 1.9–2.1 gcm−3 26 A he mic oscale, abo e
100 nm, he e ogeneous (CaO)1.8SiO2(H2O)4.0 gel and homogeneous po landi e a e a anged enclosing olumes
o wa e , e med capilla y wa e . The pic u e epo ed he e should be aken in o accoun o de eloping heo e -
ical models. Fu he mo e, syn he ic C-S-H gels (wi h Ca/Si a ios <1.4) may ha e e y di e en p ope ies as
he monolaye calcium hyd oxide componen could be absen . Finally, he new model explains a s iking ea u e
o he hyd a ion o cemen s blended wi h ly ash whe e po landi e con en is measu ed o dec ease much less
han p edic ed by he modynamic modelling. Al hough po landi e is s ill p esen , he Ca/Si a io in C-S-H is
obse ed o dec ease om close o 1.8 in plain pas es o close o 1.4 in ly ash blends58. This is now explained by
he consump ion o Ca(OH)2 monolaye componen o he C-S-H gel in he pozzolanic eac ion.
Me hods
Full de ails abou he Me hods can be ound in he supplemen a y in o ma ion
Sample p epa a ion. Monoclinic icalcium silica e, ali e, was acqui ed om Mine al Resea ch P ocessing
M.R.PRO. I s chemical composi ion de e mined by XRF was: 72.3 w % CaO, 25.5 w % SiO2, 1.1 w % Fe2O3,
0.5 w % MgO and 0.5 w % Al2O3. Fo he in si u synch o on X- ay powde di ac ion s udies, he anhyd ous
mix u es we e mixed wi h 10.00 w % o SiO2 (99.5%, Al aAesa ) as an in e nal s anda d45.
C3S_21 µm_080 labels he pas e p oduced by using as ecei ed ali e wi h a wa e - o-ali e mass a io o 0.80.
C3S_7 µm_080: The as ecei ed ali e was milled in a ib a o y mill (Re sch, mod. MM200) and he esul ing
powde was mixed wi h a wa e - o-ali e mass a io o 0.80. Fo he PDF s udy, as ecei ed ali e was a i ion
milled and hyd a ed a a wa e - o-solid mass a io o 0.80 o 16 days a 20 °C. Finally, he hyd a ion s op-
page p ocedu e was pe o med by sol en exchange wi h isop opanol and e he 59. This sample was labelled
C3S_3 μm_080_a es ed:16d.
Fo he sake o compa ison in he calo ime y s udies, an O dina y Po land Cemen (OPC) om Financie a y
Mine a S.A. has been used. The samples ha e been labelled as OPC_045, OPC_080 and OPC_080_qz o indica e
he w/s mass a ios. Fu he mo e, label _qz deno es he OPC wi h added qua z as s anda d.
Pa icle Size Dis ibu ion (PSD). A e age pa icle size and pa icle size dis ibu ion o he ali e samples
we e measu ed using a lase analyze , Mas e size S, Mal e n, UK.
BET su ace a ea. The speci ic su ace a eas o he selec ed samples we e measu ed by mul i-poin N2
adso p ion wi h a BET (ASAP 2420, Mic ome i ics, USA) ins umen .
Calo ime y. The iso he mal calo ime ic s udy was pe o med in an eigh channel The mal Ac i i y Moni o
(TAM) ins umen using glass ampoules. The hea low was collec ed up o 7 days a 20 °C.
The mal analysis. Di e en ial he mal analysis (DTA) and he mog a ime ic (TGA) measu emen o
C3S_3 μm_080_a es ed:16d was pe o med in a SDT-Q600 analyze om TA ins umen s (New Cas le, DE).
NMR s udy. 29Si MAS-NMR (Magic Angle Spinning Nuclea Magne ic Resonance) spec um o
C3S_3 μm_080_a es ed:16d was eco ded a RT on a B uke AVIII HD 600 NMR spec ome e ( ield s eng h o
14.1 T) a 156.4 MHz. The Chemical shi was e e enced o an ex e nal solu ion o e ame hylsilane.
Labo a o y X- ay powde di ac ion (LXRPD) wi h in e nal s anda d. LXRPD da a o
C3S_3 μm_080_a es ed:16d was collec ed on a D8 ADVANCE (B uke AXS) di ac ome e (SCAI – Uni e sidad
de Malaga) equipped wi h a Johansson monoch oma o , using s ic ly monoch oma ic Mo-Kα1 adia ion,
λ = 0.7093 Å, in ansmission geome y (θ/θ). Sample was mixed wi h 20 w % o in e nal s anda d (α-Al2O3).
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Scien i ic RepoR S | (2018) 8:8544 | DOI:10.1038/s41598-018-26943-y
Synch o on X- ay powde di ac ion (SXRPD). Fo he phase e olu ion s udy, SXRPD pa e ns we e
collec ed in Debye-Sche e ( ansmission) mode using he X- ay powde di ac ion ends a ion o BL04-MSPD
beamline a ALBA synch o on (Ba celona, Spain). The o al acquisi ion ime was 6 min pe da ase . Fo he PDF
s udy, SXRPD da a o C3S_3 μm_080_a es ed:16d we e collec ed o 3 h a he same di ac ome e . The empe -
a u e inside he expe imen al hu ch was 28 °C.
Rie eld da a analysis. Rie eld analyses we e pe o med using he GSAS sui e o p og ams and he
EXPGUI g aphic in e ace60. The non-c ys alline con en (amo phous and nanoc ys alline) was de e mined by
he in e nal s anda d me hodology45.
Pai Dis ibu ion Func ion da a analysis. PDF expe imen al da a we e ob ained using PDFge X361 wi h
Qmax = 21 Å−1. Quan i a i e phase analysis was ob ained by using he PDFgui so wa e62 and CMI-di py complex
modeling so wa e63.
Elec on mic oscopy s udy. High esolu ion ansmission elec on mic oscopy (HRTEM) measu emen s
we e ca ied ou using a FEI Talos F200X mic oscope equipped wi h X FEG and supe -X EDS (Ene gy Dispe si e
Spec oscopy) sys em wi h ou silicon d i de ec o s (SDDs) which ope a es a an accele a ing ol age o 200 kV.
FEGSEM (Field Emission Gun Scanning Elec on Mic oscopy) mic og aphs and EDS analysis we e pe o med in
a Helios Nanolab 650 Mic oscope (FEI Company) wi h a e ac able CBS Backsca e de ec o (annula solid-s a e
de ice) and X-Max 50 mm2 de ec o (Ox o d ins umen s).
Da a A ailabili y. All synch o on X- ay powde di ac ion aw da a iles unde lying his a icle can be
accessed on Zenodo a h ps://doi.o g/10.5281/zenodo.1027759, and used unde he C ea i e Commons
A ibu ion license.
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5
mixed wi h 20 w % o α-Al2O3 (Al aAesa 42571) as in e nal s anda d. α-Al2O3 was p e iously
hea ed up o 1500°C o 20 hou s and sie ed <125 µm.
Synch o on X- ay powde di ac ion (SXRPD). Fo he phase e olu ion s udy, SXRPD pa e ns
we e collec ed in Debye-Sche e ( ansmission) mode using he X- ay powde di ac ion
ends a ion o BL04-MSPD beamline a ALBA synch o on (Ba celona, Spain)3. The wa eleng h,
0.61878(3) Å, was selec ed wi h a double-c ys al Si (111) monoch oma o and de e mined by using
Si640d NIST s anda d (a=5.43123 Å). The di ac ome e is equipped wi h a MYTHEN de ec o
especially sui ed o ime- esol ed and ex emely good signal- o-noise a io expe imen s. The glass
capilla ies, 0.5 mm o diame e , we e o a ed du ing da a collec ion a a speed o 100 pm o
imp o e di ac ing pa icle s a is ics. To imp o e he accu acy o he esul s, h ee SXRPD pa e ns
we e collec a h ee di e en posi ions o e e y capilla y and me ged o p oduce he inal da ase .
The o al acquisi ion ime was 6 min pe da ase (2 minu es pe pa e n) o e he angula ange 1-35º
(2θ). The empe a u e inside he expe imen al hu ch was 28ºC.
Fo he PDF s udy, SXRPD da a o C3S_3m_080_a es ed:16d we e collec ed o 3 h a he same
di ac ome e . The employed wa eleng h was 0.41236(1) Å and he glass capilla y diame e was
0.7 mm. Fi e pa e ns we e collec ed, each las ed 37 min, and me ged in o de o imp o e he
signal- o-noise a io in he la ge eco ded angula ange, 1 o 120° (2θ). No changes be ween
indi idual pa e ns we e obse ed.
Rie eld da a analysis. Rie eld analyses we e pe o med using he GSAS sui e o p og ams and
he EXPGUI g aphic in e ace4. Final global op imized pa ame e s we e: backg ound coe icien s,
ze o-shi e o , cell pa ame e s, and peak shape pa ame e s using a pseudo-Voig unc ion.
Po landi e and ali e phases p esen ed aniso opic lineshape b oadening which was i ed by using
he app oach based o mul idimensional dis ibu ion o la ice me ics5. Fo he po landi e c ys al
phase p e e ed o ien a ion was also op imized by employing he Ma ch−Dollase ellipsoidal
p e e ed o ien a ion co ec ion algo i hm6. The non-c ys alline con en (amo phous and
nanoc ys alline) was de e mined by he in e nal s anda d me hodology7,8.

6
Pai Dis ibu ion Func ion da a analysis. PDF expe imen al da a was ob ained using PDFge X39
wi h Qmax=21 Å-1. Quan i a i e phase analysis in o ma ion was ob ained om he PDF da a by
using he PDFgui so wa e10. Final global op imized pa ame e s we e: scale ac o s, uni cell
pa ame e s and ADPs pa ame e s. The del a2 alue11,12 (low- co ela ed mo ion peak sha pening
ac o ) was ixed o 2 Å2. The ins umen al pa ame e s we e ob ained by measu ing a simila da a
se o c ys alline nickel. Nickel PDF da a analysis con e ged o Qdamp=0.0030 Å-1 and
Qb oad=0.0073 Å-1. The e inemen o he di e ence cu e (be ween 2 and 10 Å) was pe o med
by means o CMI-di py complex modeling so wa e13, wi h a s uc u al model cons i u ed o a
nanopa icle o single-po landi e, wi h no assump ion o pe iodici y. Final op imized pa ame e s
we e: scale ac o , s e ching in he h ee di e en c ys allog aphic di ec ions, and ADP pa ame e
o Ca a oms. This e ined nanopa icle was hen used (and he s uc u al pa ame e s ixed), oge he
wi h he c ys alline phases, in he i o he PDF (2-10 Å) again wi h CMI-di py.
Elec on mic oscopy s udy. High esolu ion ansmission elec on mic oscopy (HRTEM)
measu emen s we e ca ied ou using a FEI Talos F200X mic oscope equipped wi h X FEG and
supe -X EDS sys em wi h ou silicon d i de ec o s (SDDs) which ope a es a an accele a ing
ol age o 200 kV. Spec a we e collec ed in Scanning TEM (STEM) mode. The sample was placed
on a 200 mesh coppe g id coa ed wi h o m a and ca bon. Fo he ield emission gun scanning
elec on mic oscopy (FEGSEM) s udy, he selec ed samples (g ound powde ) we e co e ed wi h
i idium. FEGSEM mic og aphs and EDS analysis we e pe o med in a Helios Nanolab 650
Mic oscope (FEI Company) wi h a e ac able CBS Backsca e de ec o (annula solid-s a e de ice)
and X-Max 50 mm2 de ec o (Ox o d ins umen s). Backsca e ing elec on imaging (BSEI) was
pe o med a 5 kV accele a ion, and EDS analysis a 10 kV. The so wa e AZ ec ( .1.0) was used o
quan i y.
2. Ali e sample cha ac e iza ion.
7
SXRPD da a o he anhyd ous as ecei ed ali e, C3S_21µm, was analyzed by Rie eld me hodology
employing he in e nal s anda d me hod o amo phous quan i ica ion. A mix u e be ween he M1 14
and M3 15 icalcium silica e polymo phs we e needed o ob ain he bes i .
The Rie eld quan i a i e phase analysis ga e he ollowing phase assemblage: 38.7(3) w % o M1-
Ca3SiO5, 57.9(2) w % o M3-Ca3SiO5 and 3.4(2) w % o -Ca2SiO4. The amo phous con en was
negligible o his sample. The inal uni cell pa ame e s o he M1-Ca3SiO5 con e ged o
a=9.2990(2) Å, b=7.0847(1) Å, c=12.1984(3) Å and β=116.144(1)° and o he M3-Ca3SiO5 we e
a=33.1289(8) Å, b=7.0561(2) Å, c=18.5844(4) Å and β=94.247(2)°.
The same analysis was pe o med o he ib a o y milled sample, C3S_7µm. The quan i a i e
phase analysis esul s ob ained we e he ollowing: 31.6(3) w % o M1-Ca3SiO5, 62.6(2) w % o
M3-Ca3SiO5, 2.6(1) w % o -Ca2SiO4 and 3.2(1) w % o amo phous con en . The inal uni cell
pa ame e s o he M1-Ca3SiO5 we e a=9.2999(2) Å, b=7.0857(2) Å, c=12.1995(3) Å and
β=116.148(2)° and o he M3-Ca3SiO5 we e a=33.1302(9) Å, b=7.0575(3) Å, c=18.5840(5) Å and
β=94.32(2)°.
The Rie eld analysis o he a i ion milled sample, C3S_3 m, was pe o med by using LXRPD
da a. The Rie eld quan i a i e phase analysis was he ollowing: 26.8(8) w % o M1-Ca3SiO5,
44.6(9) w % o M3-Ca3SiO5, 2.4(2) w % o -Ca2SiO4 and 26.3(1) w % o amo phous con en . The
inal uni cell pa ame e s o he M1-Ca3SiO5 con e ged o a=9.2900(8) Å, b=7.0714(11) Å,
c=12.1878(17) Å and β=116.157(8)° and o he M3-Ca3SiO5 we e a=33.051(17) Å, b=7.066(2) Å,
c=18.526(4) Å and β=94.42(4)°.
Finally, The PDF pa e n o as ecei ed Ca3SiO5 was i ed wi h he M3 s uc u e o Mumme 16 by
using PDFGui. The ob ained uni cell pa ame e s and a omic displacemen pa ame e s (ADPs)
we e: a=12.213 Å, b=7.085 Å, c=9.304 Å and β=116.1°; and 0.018, 0.011 and 0.070 Å2 o Ca, Si
and O, espec i ely. These alues we e used o he analysis o he mino ac ion p esen in he
sample C3S_3m_080_a es ed:16d pas e and only he scale ac o o ali e was e ined.
8
3. The mal analysis cha ac e iza ion o C3S_3m_080_a es ed:16d.
The he mog a ime ic cu e o C3S_3m_080_a es ed:16d pas e is shown in Supplemen a y Fig.
8. Se e al mass loss s ages a e obse ed in he mal ace. The mass loss om RT o 250°C, 17.7
w %, is mainly asc ibed o he wa e elease om C-S-H gel agg ega es. The weigh loss measu ed
be ween 250°C and 400°C, 2.4 w %, could be pa ly ela ed wi h he dehyd a ion o amo phous
calcium hyd oxide. 5.7 w % mass loss is measu ed be ween 400°C and 550°C, cen e ed a 455°C,
which co esponds o he wa e loss om c ys alline po landi e. Two inal weigh losses a e
e iden om 550 o 1000 ºC. The one obse ed close o 755ºC, 2.0 w %, is likely due o he CO2
eleased o c ys alline calci e. The o he close o 660°C, 3.8 w %, is e y likely ela ed o he CO2
elease om amo phous calcium ca bona e and p obably also o he elease o o ganic sol en , used
o he a es ing o he hyd a ion, abso bed in he C-S-H gel as p e iously epo ed17.
The componen s o he gel a e nanoc ys alline de ec i e clino obe mo i e, amo phous (monolaye )
calcium hyd oxide, and wa e wi hin he nanopo es. The weigh losses o each componen can be
compa ed wi h ha expe imen ally ob ained o he C3S_3m_080_a es ed:16d pas e. Fo ull
eac ion, he heo e ical weigh loss o he wa e gel po es, 13.27 w %, plus he wa e in
clino o bemo i e, 5.28 w %, sum 18.55 w % which is compa able wi h he expe imen al weigh loss
be ween RT o 250ºC, 17.7 w % o his pas e. Secondly, he calcula ed weigh loss om Si-OH
condensa ion and om amo phous Ca(OH)2 is 0.62 and 3.24 w %, espec i ely which can be
compa ed wi h he wa e loss obse ed be ween 250°C and 400°C, 2.4 w % plus 2.1 w % om he
con ibu ion o he ca bona ion. Finally, he expe imen al wa e loss om c ys alline po landi e, 5.7
w % is compa ible wi h he calcula ed alue acco ding o eac ion (1), main ex , 6.7 w %.
9
4. Supplemen a y ables:
Supplemen a y Table 1. Selec ed esul s o he synch o on PDF analysis o
C3S_3m_080_a es ed:16d pas e in he 10-25 Å - egion, using di e en s uc u al desc ip ions o
he nanoc ys alline ac ion o C-S-H gel.
Phase RW
(%) Ca3SiO5
(w %) C ys alline
Ca(OH)2 (w %)
Nanoc ys alline
ac ion o C-S-H
(w %)
Hilleb andi e (o), ICSD #80127 33.4 3.7 55.6 40.7
Jenni e ( ), ICSD #151413 33.5 3.3 46.5 50.2
Tobe mo i e-14 (m), ICSD #152489 33.1 2.9 44.5 52.5
Tobe mo i e-11 (o), ICSD #92941 28.5 2.5 38.3 59.1
Tobe mo i e-11 (m), ICSD #87690 28.7 2.4 36.9 60.7
Tobe mo i e-11 (o), ICSD #100405 28.4 2.5 37.2 60.4
Clino obe mo i e (m), ICSD #90036 27.4 1.8 27.1 71.1
Clino obe mo i e ( ), ICSD #90034 27.9 2.0 29.8 68.3
Clino obe mo i e (m), T5_14sc* 28.3 2.1 32.3 65.5
Clino obe mo i e (m), T5_11sc* 28.4 1.9 28.8 69.3
Clino obe mo i e (m), T3_14sc* 27.7 2.2 33.5 64.3
*Richa dson, 2014 18; (m), (o) & ( ) deno es monoclinic, o ho hombic and iclinic, espec i ely.
10
5. Supplemen a y Figu es:
Supplemen a y Figu e 1. Pa icle size dis ibu ion (diame e ) and cumula i e measu ed in olume,
o he ollowing ma e ials (a) as ecei ed ali e, (b) ib a o y milled ali e and (c) a i ion milled ali e.
0
10
20
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1.0 10.0 100.0
D ,50 =2.7m
0
10
20
0
10
20
30
40
50
60
70
80
90
100
()
0
10
20
0
10
20
30
40
50
60
70
80
90
100
D ,50 =7.4m
size (m)
olume (%)
Cumula i e olume (%)
(c)
(b)
(a)
D ,50 =20.8m
D ,90 =70.7m
D ,90 =20.5m
D ,10 =1.0m
D ,10 =3.1m
D ,90 =8.0m
D ,10 =0.8m

11
Supplemen a y Figu e 2. SXRPD Rie eld plo s a 14 hou s o hyd a ion o (a) C
3
S_21µm_080
and (b) C
3
S_7µm_080. The main peaks a e labelled as ollow: po landi e (), ali e ( ) and added
in e nal s anda d, SiO
2
( ).
12
Supplemen a y Figu e 3. (a) LXRPD (Mo-Kα1 adia ion) Rie eld plo o
C
3
S_3m_080_a es ed:16d. The main peaks a e labelled as ollow: po landi e (), ali e ( ) and
added in e nal s anda d, -Al
2
O
3
( ), (b) Simula ed XRD pa e n o he de ec i e
clino obe mo i e T3_14sc s uc u e wi h pa icle size o app oxima ely 5nm, using he same
wa eleng h (Mo-Kα1 adia ion) and (c) Raw SXRPD pa e n o he PDF s udy o
C
3
S_3m_080_a es ed:16d pas e. SXRPD pa e n o he emp y capilla y is also shown ( ed
line)
13
Supplemen a y Figu e 4.
29
Si MAS-NMR spec a o (a) C3S_3µm_080_a es ed:16d, (b)
C3S_3µm_080_non-a es ed:32d (a second p epa a ion ba ch o he 3 m ali e sample) and (c)
C3S_13µm_080_a es ed:34d. The Mean Chain Leng h alues a e depic ed and he in ensi y o he
Q
0
esonances indica es he un eac ed ali e ac ion. Spinning a e o 15 kHz and a magne ic ield o
14.1 T.
14
Supplemen a y Figu e 5. High-angle annula da k- ield scanning ansmission elec on (HAADF-
STEM) mic og aph o C
3
S_3m_080_a es ed:16d. Th ee independen analyses ob ained by EDS
a e also included as examples.
Supplemen a y Figu e 6. Field emission gun scanning elec on (FEGSEM) mic og aph o
C
3
S_3m_080_a es ed:16d.
21
C3Sm_080_28d_b_ALL.da : C3S_7µm_080 a 28d o hyd a ion
C3S_milled_080_3m_ALL.da : C3S_7µm_080 a 3m o hyd a ion
Pai Dis ibu ion Func ion s udy o nanoscale analysis and cha ac e iza ion
emp y0p7_ALL.da : emp y capilla y.
Ni0p7_ALL.da : Nickel sample employed as s anda d.
C3S_080_milled_Ma zo_ALL.da : C3S_3m_080_a es ed:16d.

22
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