Enhancing he ma ix- ibe bond in ul a-high-pe o mance ibe - ein o ced
conc e e using a high pe o mance plas icize . Impac on he lowabili y,
physical and mechanical p ope ies
J.D. Ruiz Ma ínez
a
, J.D. Ríos
b
, E.M. P´
e ez-So iano
c
, H. Ci uen es
b,*
, C. Lei a
a,*
a
Depa men o Chemical and En i onmen al Enginee ing, Escuela T´
ecnica Supe io de Ingenie ía, Uni e sidad de Se illa, Se ille 41092, Spain
b
Depa men o Con inuum Mechanics and S uc u al Analysis, Escuela T´
ecnica Supe io de Ingenie ía, Uni e sidad de Se illa, Se ille 41092, Spain
c
Depa men o Ma e ials Science and Enginee ing and T anspo , Escuela Poli ´
ecnica Supe io , Uni e sidad de Se illa, Se ille 41011, Spain
ARTICLE INFO
Keywo ds:
Ul a-high-pe o mance ibe - ein o ced con-
c e e
High pe o mance plas icize
The mo-g a ime ic analysis
Po osi y
Comp essi e s eng h
Flexu al s eng h
ABSTRACT
One o he main p oblems in he use o ul a-high-pe o mance ibe - ein o ced conc e e (UHPFRC) wi h s eel
ibe s is low lowabili y. The addi ion o 2,3,4,5,6-Pen ahyd oxycap oic acid sodium sal (SPS) in small amoun s
(0.05, 0.1 and 0.15 %w o he cemen con en ) can signi ican ly inc ease he lowabili y and se ing ime. The
e ec s on po osi y, ma ix chemical composi ion and ibe -ma ix in e ac ion we e examined, as well as i s in-
luence on s eng h. Imp o ing he lowabili y, po es la ge han 50
μ
m show a signi ican dec ease, while hose
smalle han 0.1
μ
m show a signi ican inc ease. Acco ding o he esul s o he mo-g a ime ic analysis, he
p oduc ion o e ingi e wi h ine g ains and s agge ed symbiosis imp o es he po e s uc u e o he UHPFRC
ma ix. An imp o emen o he adhesion o he s eel ibe s o he ma ix was de e mined by s e eomic oscope
images, showing e idence o a ela ionship be ween SPS dosage and he expanded conc e e a ea su ounding he
ibe . The lexu al and comp essi e s eng h inc eased by 10 % and 8 %, espec i ely, when he plas icize /
cemen a io was 0.15 %.
1. In oduc ion
Wi hin he cons uc ion, conc e e s ands as a p o oundly u ilized
ma e ial due o i s no able a ibu es, including i s excep ional
comp essi e s eng h, du abili y, cos -e ec i eness, abundan a ail-
abili y o cons i uen ma e ials, and i s adap abili y o a ious shapes
achie able h ough di e se cas ing molds [1]. A ound he wo ld, con-
c e e is he mos widely used building ma e ial o esiden ial and
comme cial s uc u es [2]. App oxima ely 4.1 billion ons o cemen a e
p oduced annually wo ldwide [3].
Ul a-high-pe o mance ibe - ein o ced conc e e (UHPFRC) ep e-
sen s an inno a i e cemen -based composi e ma e ial enowned o i s
exceedingly high s eng h, excep ional du abili y, and ema kable
oughness. The componen s u ilized in he o mula ion o UHPFRC
p edominan ly encompass cemen i ious ma e ials, qua z sand, chemi-
cal addi i es, and wa e , among o he s [4–6]. As a esul ,
ul a-high-pe o mance ibe - ein o ced conc e e (UHPFRC) was de el-
oped and is ega ded as one o he mos p omising ma e ials o u u e
sus ainable and esilien in as uc u e [7,8]. This conc e e o e s
signi ican ly imp o ed mechanical p ope ies, pa icula ly in ensile and
lexu al s eng h. I s ein o cemen , ypically consis ing o s eel ibe s in
amoun s exceeding 2 % by olume, also p o ides excep ional ene gy
abso p ion capaci y and duc ili y [9]. The demand o UHPFRC con-
inues o g ow due o i s use in la ge s uc u es. One applica ion o his
ma e ial is i s employ in s uc u es designed o s o age o p oduc ion o
he mal ene gy, such as s eam s o age anks in sola he mal powe
plan s o sal s o age anks [10]. Compa ed o con en ional conc e e,
UHPFRC is known o ha e highe iscosi y and pumping losses. Hence,
admix u es, including e a de s and addi ional plas icize s, mus be
inco po a ed [11].
The in eg a ion o s eel ibe s is widely acknowledged o po en ially
dec ease he lowabili y o ul a-high pe o mance ibe - ein o ced
conc e e (UHPFRC), esul ing in inc eased ai con en in i s esh
s a e, and consequen ly, heigh ened po osi y in he ha dened s a e [12].
Resea ch has indica ed ha UHPFRC mix u es inco po a ing ibe s wi h
a smalle aspec a io a e mo e wo kable, e en a highe ibe dosages,
compa ed o mix u es wi h ibe s possessing a la ge aspec a io.
Howe e , i ’s no ed ha ibe s wi h smalle adio end o lowe s eng h
* Co esponding au ho s.
E-mail add esses: [email p o ec ed] (H. Ci uen es), [email p o ec ed] (C. Lei a).
Con en s lis s a ailable a ScienceDi ec
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Recei ed 17 Ap il 2024; Recei ed in e ised o m 10 Feb ua y 2025; Accep ed 2 Ma ch 2025
Cons uc ion and Building Ma e ials 470 (2025) 140683
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0950-0618/© 2025 The Au ho s. Published by Else ie L d. This is an open access a icle unde he CC BY license (
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[4,12,13].
Fu he mo e, imp o ed pe o mance equi es a dense mic os uc-
u e, which in combina ions wi h e y li le wa e con en canno be
en i ely achie ed by aising he indi idual pa icle’s deg ees o eac-
i i y [14]. As a consequence, a high-pe o mance supe plas icize is a
c ucial elemen in he p epa a ion o UHPFRC, imp o ing i s heology
[15]. E ec i e physical packing o binde pa icles in he mic os uc u e
is necessa y, equi ing ca e ul ma e ial selec ion based on syne gis ic
size dis ibu ions as well as a ailabili y and eac i i y [14]. O e he
pas hi y yea s, he p ima y cons i uen s o supe plas icize s ha e been
syn he ic wa e -soluble polyme s, including modi ied suga - ee ligno-
sul ona e, sul ona ed naph halene o maldehyde condensa e, and sul-
ona ed melamine o maldehyde condensa e [16,17]. In he las en
yea s, se e al ad anced supe plas icize s ha e been de eloped, all o
which a e based on he polyca boxyla e polyme s amily as ca bohy-
d a e eas e s which main mechanism is he s e ic hind ance e ec [18,
19]. None heless, solely u ilizing hese supe plas icize s o en ails o
mee he UHPRFC’s combined luidi y loss s anda ds [10,20].
2,3,4,5,6-Pen ahyd oxycap oic acid sodium sal (SPS) is an o ganic
elec oly e known o i s high wa e solubili y. SPS, ha also ac s as a
high pe o mance plas icize [21,22]. While SPS alone has a ela i ely
low wa e educ ion a e, i can make a signi ican di e ence imp o ing
he wa e educ ion a e o imp o e he conc e e’s lowabili y and lessen
slump loss when pai ed wi h o he supe plas icize [10,21]. The addi-
ion o SPS can delay cemen hyd a ion, educe he adso p ion and in-
c ease he o he supe plas icize concen a ion in solu ion, leading o
inc eased luidi y o conc e e and educed slump loss [10].
Se e al hypo heses ou line he se ing e a ding mechanism o
2,3,4,5,6-Pen ahyd oxycap oic acid sodium sal . Fi s ly, i is p oposed
ha SPS impedes he hyd a ion p ocess o icalcium silica e (C
3
S) by
adso bing on o speci ic dissolu ion si es on he su ace o he silica e
phase. This leads o diminished hyd a ion hea and a e, he eby
ex ending he induc ion pe iod and delaying he se ing [23–25].
Ano he pe spec i e sugges s ha he adso p ion o complexa ion o SPS
wi h Ca
2 +
hinde s he o ma ion o e ingi e (AF ) [21,24]. Fu he -
mo e, he e is a no ion ha SPS delays AF o ma ion by impeding he
dissolu ion o calcium sul a e dihyd a e (CaSO
4
⋅2 H
2
O), which is c ucial
o AF p oduc ion [22]. Addi ionally, a heo y e ol es a ound he
con ol o calcium hyd oxide (CH) c ys als, indica ing ha SPS sup-
p esses he ypical p ecipi a ion o CH by es ic ing he g ow h o CH
nuclei. Ne e heless, he p edominan ole among hese ou mecha-
nisms and hei in e ela ion emains unclea a p esen [10,24].
Subsequen in es iga ions ha e shed ligh on he co ela ion be-
ween he e a ding e ec o supe plas icize s and i s dosage. A lowe
le els, supe plas icize s p o e insu icien o ully coun e ac he ac i e
dissolu ion si e o C
3
S [24], he eby limi ing he a ailabili y o acid o
adso p ion on o he icalcium alumina e (C
3
A) su ace. Consequen ly,
he p ima y mechanism o e a da ion a lowe dosages p edominan ly
in ol es he inhibi ion o calcium silica e nuclea ion and es ic ing he
o ma ion and expansion o hyd a ion p oduc s [22]. Con e sely, highe
dosages esul in he comple e adso p ion o esidual supe plas icize
on o he C
3
S su ace, leading o heigh ened hyd olysis and concen a-
ions o supe plas icize and Na
+
. The excess o supe plas icize hen
hampe s he dissolu ion o CaSO
4
⋅2 H
2
O and, upon binding o Ca
2+
, is
adso bed on o he C
3
A su ace, hinde ing C
3
A hyd a ion and AF o -
ma ion. Consequen ly, ele a ed supe plas icize s dosages no only delay
C
3
S hyd a ion bu also impede AF o ma ion by es aining he disso-
lu ion o CaSO
4
⋅2 H
2
O. The e o e, because excessi e SPS addi ion
signi ican ly e a ds hyd a ion, se ing ime can be no iceably ex ended
[21,22]. Longe se ing imes can assis educe he isk o p ema u e
se ing in la ge-scale cons uc ion p ojec s o in ho a eas, enabling
imp o ed wo kabili y and mo e con olled ma e ial placemen [26].
Longe se ing imes can also lessen he chance o c acks om quick
sh inkage, which will inc ease he conc e e’s li e ime and du abili y [27,
28]. Saladi e al. ound in hei wo k ha by adding a blend o supe
plas icize s o a high-pe o mance cemen , he inal se occu ed
be ween 11 and 24 h [29].
Di e en cemen a ie ies showcased dis inc op imal dosages,
highligh ing conce ns ega ding supe plas icize s -cemen compa i-
bili y. Howe e , he mechanism unde lying supe plas icize s’
enhancemen o cemen comp essi e s eng h emains elusi e, since he
amoun o supe plas icize , as well as i s aspec a io, has a ied in
p e ious in es iga ions. Ma e al. [24] p opose ha high pe o mance
plas icize al e s he calcium silica e hyd a e su ace ene gy (C-S-H)
h ough adso p ion, he eby augmen ing C-S-H cohesion and bols e ing
comp essi e s eng h. Ren e al. [25] epo ed ha small amoun s o SPS
con ibu e o inc ease he conc e e se ing and s eng h de elopmen
[30] Howe e , excessi e supe plas icize con en may inc ease po osi y,
a ec long- e m du abili y, and aise p oduc ion cos s [31]. Al hough no
ad e se e ec s we e obse ed wi hin he dosage ange analyzed in his
s udy, SPS con en op imiza ion should ake hese ac o s in o accoun .
Fu he mo e, he syne gis ic e ec o mul iple admix u es is no ye ully
unde s ood, as hei combina ion can al e iscosi y, hixo opy, and he
s uc u al pe o mance o he ma e ial [32].
This pape del es in o he in es iga ion o he e ec o SPS on
UHPFRC. The explo a ion ocuses on h ee di e en dosages o SPS, as
es ablished in p e ious esea ch, aiming o comp ehend hei in luence
on he physical and mechanical p ope ies o his ad anced ma e ial.
Va ious e alua ion me hods ha e been employed o analyze and cha -
ac e ize he p ope ies o SPS-modi ied UHPFRC, wi h he objec i e o
del ing in o he al e a ions induced by his admix u e on he s uc u e
and pe o mance o conc e e. This mul i ace ed app oach aims o p o-
ide a comp ehensi e and de ailed unde s anding o he e ec s ha SPS
can exe on UHPFRC, hus con ibu ing o he knowledge in he ield o
high-s eng h cons uc ion ma e ials.
2. Ma e ials and me hods
2.1. Ma e ials and mix p epa a ion
Th ee di e en ma e ials we e u ilized as binde s in his s udy. Type I
cemen o 52.5 R/SR, acco ding o EN 197–1 [33], was p oduced by
Po land Valde i as. The SF S-92-D silica ume was p o ided by he
SIKA company, while he g ound-g anula ed blas - u nace slag (GGBS)
was ob ained om he A celo -Mi al company. The SF S-92-D silica
ume was p o ided by he SIKA company, while he g ound-g anula ed
blas - u nace slag (GGBS) was p ocu ed om A celo -Mi al. Rega ding
he agg ega es used, wo ypes o qua z sand we e u ilized: he ines
sand (FS) wi h a maximum pa icle size o 0.315 mm, and he coa se
sand (CS) wi h a pa icle size below 0.800 mm [34]. S eel ibe s
measu ing 13 mm in leng h and 0.2 mm in diame e , sou ced om
Beckae , we e also employed. The supe plas icize (20HE) was supplied
by SIKA, while SPS wi h a pu i y o 99.8 % was ob ained om Scha lab.
The chemical composi ions o he binde ma e ials we e analyzed using
X- ay luo escence spec ome y and a e de ailed in Table 1.
Fou di e en o mula ions o UHPFRC we e p oduced, each
di e ing in he quan i y o SPS inco po a ed. The ma ix dosage
emained consis en ac oss all mix u es ( e e o Table 2), whe eas
a ying p opo ions o SPS addi ions we e added (0 %, 0.05 %, 0.10 %,
and 0.15 % o he cemen con en ). These ou o mula ions a e deno ed
as SPS-0 ( ep esen ing he conc e e e e ence), SPS-0.05, SPS-0.10, and
SPS-0.15, espec i ely.
Fi s , he solid ma e ials (cemen , silica ume, blas u nace slag, ine
and coa se agg ega e, and SPS) we e added o he e ical mixe and
mixed o ou minu es. Nex , he supe plas icize was added o he
wa e and mixed o one minu e o achie e a homogeneous liquid.
Finally, all cons i uen s (solids and liquids) we e mixed o 20 minu es o
achie e he desi ed consis ency o he mix u e. A e wa d, he s eel i-
be s we e added and mixed o an addi ional i e minu es. In his s udy,
he ex ended mixing ime was no a esul o he addi ion o SPS. Ins ead,
i was necessa y o ensu e he mix u e a ained he op imal consis ency
and wo kabili y equi ed o UHPC. This p ocess was ca e ully
J.D. Ruiz Ma ínez e al.
Cons uc ion and Building Ma e ials 470 (2025) 140683
2
con olled o main ain he in eg i y and pe o mance o he ma e ial.
Each mix u e was hen u ilized o cas h ee p isms measu ing 40 mm
×40 mm ×160 mm. A e 48 hou s, he specimens we e emo ed om
hei molds and subme ged in wa e a oom empe a u e o 25 days o
cu e.
2.2. Expe imen al me hods
2.2.1. The mo-g a ime ic analysis
A he mo-g a ime ic s udy (TG-SDTA Me le -Toledo 851) was
conduc ed om oom empe a u e o 600◦C. To his end, samples o
100–150 mg o he TG-SDTA measu emen s we e aken om he su -
ace o he es panels. A hea ing a e o 10 ◦C/min was chosen, using ai
as he pu ging gas.
2.2.2. Ab ams minia u e slump es
A modi ied minia u e slump es was de ised o assess he wo k-
abili y o esh conc e e, ollowing he guidelines ou lined in EN
12350–2:2020 [35]. The se up o he mini-slump es , depic ed in
Fig. 1, employed a scaled-down geome ic Ab ams cone wi h speci ic
dimensions: 50 mm diame e a he op, 100 mm diame e a he base,
and 150 mm heigh . The es was conduc ed on a la su ace composed
o he same ma e ial. A e es ing in acco dance wi h he s anda d
p ocedu e, measu emen s we e aken using a s anda d gauge wi h
one-millime e p ecision, and he esul s we e a e aged ac oss ou
eadings.
2.2.3. Ini ial and inal se ing ime
The pene a ing esis ance app oach desc ibed in he EN 196–3:2017
was used o de e mine he UHPFRC’s ini ial and inal se ing ime ames
[36]. This me hod desc ibes he p ocedu e o gauging he ini ial and
inal se ing imes o conc e e. The ini ial se ing ime is pinpoin ed as
he momen a needle pene a es he cemen pas e 6 ±3 mm. The inal
se ing ime is iden i ied when he needle can no longe pene a e he
cemen pas e by mo e han 0.5 mm.
2.2.4. Hea o hyd a ion
The hea o hyd a ion o UHPC was measu ed a di e en ial scanning
calo ime e (TA DSC 2920 Ins umen ), To p epa e he samples and
analyze he in luence o he binde , s eel ibe s we e emo ed, and he
o he componen s base pe cen age and he mixing du a ion we e man-
eined, because only 2 g we e pu in o he calo ime e . The empe a u e
in he calo ime e was always main ained a 20 ◦C du ing he es and
he hea low was eco ded o 40 h.
2.2.5. S e eomic oscope
The s e eomic oscopic allows imaging a la ge ield o iew, p o ides
p ecise mic oscopic de ails in 3D, and i allows quan i a i e measu e-
men s [37–40]. The obse a ions ob ained om his app oach align wi h
p e ious s udies [41–44], u he alida ing he applicabili y o his
me hod o examine he ibe -ma ix bonding in UHPRC.
A Nikon model SMZ25 mic oscope (New Yo k, U.S.A.), commonly
e e ed o as a s e eomic oscope, was used o his s udy. The ins u-
men is connec ed o a compu e equipped wi h NIS Elemen s BR so -
wa e, h ough which he images we e cap u ed. Fo he examina ion,
small specimens measu ing 20 mm×40 mm x 40 mm we e ab ica ed
o he pu pose o using his mic oscope.
In addi ion o he magni ica ion o he images, he u ilized equip-
men gene a ed a 3D model o he image and a Z-axis g aph. This g aph
delinea es, wi h mic ome ic p ecision, he p o ile o he mix u e su -
ace, enhancing he dep h o analysis.
2.2.6. Po osi y
A po osime y s udy was ca ied ou using a Mic ome i ics Au opo e
IV me cu y in usion po osime e (No c oss, U.S.A.). The analysis
co e ed a po e size ange spanning om 0.007 o 150
μ
m. To p epa e
he samples, hey we e shaped in o 5 mm pelle s, and subsequen ly
d ied in an o en a 105◦C. Key pa ame e s included a su ace ension o
480 mN/m, a con ac angle o 140◦, and a maximum applied p essu e o
413 MPa. These ac o s we e c i ical in ensu ing accu a e and eliable
Table 1
XRF chemical composi ion o binde ma e ials and mix composi ion o e e ence
conc e e (kg/m
3
).
Cemen GGBS SF
CaO 45.61 35.12 0.30
SiO
2
18.29 27.81 79.58
Al
2
O
3
6.59 9.83 0.20
SO
3
4.02 - -
Fe
2
O
3
2.85 0.31 0.06
K
2
O1.09 2.01 0.42
MgO 1.00 6.63 0.35
TiO
2
0.41 0.48 -
Na
2
O0.29 0.21 0.12
P
2
O
5
0.13 - -
Cl
2
O
3
0.07 - -
BaO 0.06 - -
S O 0.05 0.08 -
MnO
2
0.05 0.11 -
CuO 0.04 - -
ZnO 0.02 - -
Table 2
Mix p opo ions and designa ion.
Cons i uen (kg/m
3
)
Mix Cemen SF GGBS FS CS Wa e SP S eel ibe s SPS
SPS−0 540 210 310 470 470 205 42 196 0
SPS−0.05 540 210 310 470 470 205 42 196 2.7
SPS−0.10 540 210 310 470 470 205 42 196 5.4
SPS−0.15 540 210 310 470 470 205 42 196 8.1
Fig. 1. Ab ams minia u e slump es o esh conc e e.
J.D. Ruiz Ma ínez e al.
Cons uc ion and Building Ma e ials 470 (2025) 140683
3
po osi y measu emen s
2.2.7. Mechanical p ope ies
2.2.7.1. Comp essi e s eng h. The e alua ion o comp essi e s eng h
was conduc ed on h ee cubic samples o 40 mm o side, o each ype o
conc e e, ollowing he guidelines o he EN 12390–3 s anda d [45].
These assessmen s ook place using a se o-hyd aulic es ing machine
wi h a load capaci y o 3000 kN. Each mix was ep esen ed by six
samples measu ing 80 mm ×40 mm ×40 mm.
2.2.7.2. Flexu al ensile s eng h. Th ee-poin bending es s we e pe -
o med o each ype o manu ac u ed conc e e, u ilizing p isma ic
specimens wi h dimensions o 40 mm×40 mm×160 mm. The esidual
s eng h is calcula ed using Eq. (1), and he es s and ou comes we e
ca ied ou in acco dance wi h he EN 14651 s anda d [46].
Rj =3PjL
2bh2
sp
(1)
whe e Rj and Pj, which co ela e o CMODj, espec i ely, s and o he
applied load and he esidual lexu al ensile s eng h. In pa icula , he
ma ching CMOD alues o 0.5 mm, 1.5 mm, 2.5 mm, and 3.5 mm we e
used o de e mine R1, R2, R3, and R4. The a iables b, hsp, and L
ep esen he beam’s wid h, no ch heigh , and span leng h, espec i ely,
in Eq. (1).
The es s we e conduc ed using hyd aulic equipmen wi h a
maximum load capaci y o 50 kN, employing (c ack mou h opening
displacemen ) CMOD displacemen con ol. Bo h he suppo and
loading olle s we e equipped wi h an i- o sion mechanisms. In addi ion
o measu ing he 5 mm CMOD, de lec ion a he cen e o he specimen
was eco ded using a 10 mm e ical ansduce (Fig. 2). Following he
ailu e o all specimens, a isual inspec ion o he ac u e zone
con i med ha he ac u es esul ed om bending.
The de e mina ion o he Young’s modulus was ca ied ou based on
he esul s o he load-CMOD cu es, ollowing he guidelines p o ided
by Jenq and Shah [47]. To do his, he ini ial slope o he load-CMOD
cu e was used, and, knowing he dimensions o he specimens used
in he h ee-poin bending es s, he Young’s modulus was calcula ed o
each es .
3. Expe imen al esul s
3.1. The mo-g a ime ic analysis
Se e al peaks we e obse ed in he TG cu es depic ed in Fig. 3,
anging om 50◦C o 600◦C. The ini ial endo he mic peak is a 50◦C
a ibu ed o humidi y e apo a ion, ollowed by dehyd a ion o C-S-H
and e ingi e a 90◦C. The hi d endo he mic peak a 148◦C was caused
by he dehyd a ion o hyd a ed calcium alumina es, ollowed by he
ou h peak a 435◦C due o he decomposi ion o calcium hyd oxide.
Al hough he adso p ion o SPS o he complex be ween SPS and calcium
ions (Ca
2+
) inhibi s he o ma ion o e ingi e du ing he se ing ime,
he e is an small inc ease in e ingi e a 28 days. This is e iden in he
le wa d shi o he second peak a 0. Al hough no majo changes we e
obse ed in he cemen i ious ma ix, i is obse ed ha he addi ion o
15 % SPS gene a ed mo e e ingi e wi h ine g ains and s agge ed
symbio ics in in e aces and po es, due o he dehyd a ion o he
e ingi e.
3.2. Ab ams minia u e slump es
The esul s o he Ab ams slump es s o each mix a e depic ed in
Figs. 4 and 5. No ably, hese igu es e eal a consis en end: as SPS
con en inc eases, he sp ead alues also inc ease. Fo ins ance, a an
SPS/cemen a io o 0.15, he e is a subs an ial 55 % inc ease compa ed
o he UHPFRC wi hou high pe o mance plas icize . Fu he mo e, i is
wo h highligh ing ha all mixes including SPS ha e been inc eased in
wo kabili y, while main aining consis en iscosi y and uni o m ex u e
h oughou he p ocess, de oid o he need o ib a ion.
On he con a y, as a as he conc e e slump is conce ned, a
consis en posi i e e ec end is ollowed, mi o ing he slump low
ela ionship, which in a iably de e mines he luidizing e ec o SPS on
conc e e. Addi ionally, i is also no iceable ha none o he pas es
exhibi ed signi ican de o ma ion o seg ega ion du ing he mini-slump
es , as illus a ed in Fig. 5.
P e ious s udy [24] demons a ed ha he luidi y o SPS-doped
cemen mo a was g ea e han ha o mo a wi hou SPS, wi h he
maximum e ec i e dose being 0.03 %, beyond his dosage, he wo k-
abili y o he cemen mo a did no imp o e u he . In UHPFRC, a
simila e ec can be obse ed; howe e , he addi ion o wo o he
binde s alongside cemen allows highe dosages o con inue enhancing
wo kabili y.
3.3. Ini ial and inal se ing ime
In Fig. 6, he p og ession o pene a ion esis ance wi hin he
UHPFRC ma ix is depic ed using he Vica needle es appa a us o all
SPS mixes. No ably, i is e iden ha he highe he SPS dosage, he
longe he delay in he build-up o ma ix pene a ion esis ance, he eby
ex ending bo h ini ial and se ing imes.
Fo he de e mina ion o se ing imes, Eq. (2) was applied h ough
eg ession analysis as desc ibed by:
log(PR) = a+b⋅log( )(2)
whe e log (PR) ep esen s he pene a ion dis ance in millime e s,
signi ies he elapsed ime in minu es, and a and b deno e he eg ession
coe icien s. The esul ing eg ession coe icien s, coe icien o de e -
mina ion (R
2
), and he ini ial and inal se ing imes a e p esen ed in
Table 3.
As shown in Fig. 6, he e a e di e ences o 10.5 hou s be ween he
ini ial se ing ime o SPS-0 and SPS-0.05. Howe e , hese dispa i ies
escala e o 16.7 and 25.7 hou s o SPS-0.10 and SPS 0.015 espec i ely,
compa ed o SPS-0. The di e ences become mo e p onounced a he
inal se ing ime, since he dosages wi h highe SPS in hei composi ion
ook 18.8 (SPS-0.10) and 27.1 (SPS-015) hou s longe han SPS-0 o se ,
Fig. 2. Se ing up and ins umen ing h ee-poin bending es s.
J.D. Ruiz Ma ínez e al.
Cons uc ion and Building Ma e ials 470 (2025) 140683
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hus accumula ing an inc ease o 204.3 % and 295 % espec i ely in he
inal se ing ime.
Addi ionally, he inclusion o SPS esul ed in a p opo iona e in-
c ease in he dispa i y be ween he ini ial and inal se ing ime ames.
The ime window expanded by 7.6 % o he dosage wi h he lowes SPS
addi ion, while eaching a 61 % inc ease o he composi ion wi h he
highes SPS. These esul s indica e ha SPS p ima ily unc ions ha e
been o delay bo h he ini ial and inal se ing imes, as well as o widen
he ime gap be ween hem. Consequen ly, hese changes will e lec in
he physical and mechanical p ope ies o he composi ions.
While his cha ac e is ic may limi he use o SPS in ce ain ime-
sensi i e applica ions, i can p o ide signi ican bene i s in o he s, and
we belie e hese po en ial applica ions wa an u he explo a ion. The
p olonged se ing imes in conc e e mix u es can o e se e al ad an-
ages in speci ic applica ions. Fo example, in la ge-scale cons uc ion
p ojec s o in ho clima es, longe se ing imes can help mi iga e he isk
o p ema u e se ing, allowing o be e wo kabili y and mo e
con olled placemen o he ma e ial. Fu he mo e, ex ended se ing
imes can educe he isk o c acks due o apid sh inkage [48–50]. ul-
ima ely con ibu ing o he du abili y and longe i y o he conc e e.
3.4. E ec o SPS on UHPC hea o hyd a ion
Fig. 7 illus a es how he hyd a ion hea low a ies wi h a ying SPS
doses.
Exo he mic we ing and an ea ly-s age eac ion a e esponsible o
he i s peak in Fig. 7, esul ing in a gela inous coa ing con aining
e ingi e ods [24]. Subsequen ly, he e is a ime in e al known as he
induc ion pe iod, whe e he hea low emains almos cons an (b ween
he end o he i s peak and he beginning o he second). The second
Fig. 3. The mo-g a ime ic analysis o SPS-0 and SPS-0.15 a 28 days.
Fig. 4. Mini slump low o UHPFRC wi h di e en SPS con en s.
J.D. Ruiz Ma ínez e al.
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peak co esponds o he pe iod whe e he p ima y p oduc s, C–S–H and
CH, a e p oduced, and is known as he accele a ion pe iod [24].
The hyd a ion eac ion p ocess is closely ela ed o he cemen
se ing p ocess. The di e ence be ween he ini ial and inal se ing imes
co espond o he s a and inish o he accele a ion pe iod ( he ime
be ween he s a o he second peak and he maximum poin o ha
second peak) in he hyd a ion p ocess. [51].
The addi ion o SPS conside ably changed he hyd a ion kine ics.
The induc ion pe iod inc eased d ama ically wi h he inc ease in SPS
dosage, sugges ing ha SPS delayed he hyd a ion o CH and C-S-H,
p oducing ha he accele a ion pe iod began wi h a delay, which is
consis en wi h he di e ence in he ini ial se ing ime. The s udy’s
expe imen al indings mos ly concu wi h hose o SPS in con en ional
cemen [24].
Fig. 5. Mini slump low esul s o each mix: a) SPS-0, b) SPS-0.05, c) SPS-0.10, and d) SPS-0.15.
Fig. 6. Ini ial and inal se ing ime.
J.D. Ruiz Ma ínez e al.
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3.5. S e eomic oscope
Fig. 8 displays images depic ing he bond be ween one s eel ibe and
he cemen i ious ma ix, ini ially posing challenges in disce ning any
no iceable impac o SPS. None heless, Fig. 9 po ays he p o ile o med
in he a ea jus p eceding he appea ance o he s eel ibe , showcased a
he cen e o Fig. 9, e ealing compelling e idence ha sugges s a co -
ela ion be ween he dosage o SPS and he enla ged a ea o conc e e
su ounding he ibe .
The esul s depic ed in Fig. 9 p omp he hypo hesis ha he luid-
iza ion o he cemen i ious mix could po en ially enhance he adhesion
o he s eel ibe s. Fu he mo e, i is in e ed ha in UHPFRC con aining
app oxima ely 2 % s eel ibe s, he luidiza ion o he cemen i ious
ma ix acili a es a mo e uni o m o ma ion, he eby diminishing
no able po es and po en ially augmen ing he con ac o he ma ix and
ibe s and he ic ion du ing a pull-ou es [52].
3.6. Po osi y
Po osi y plays a undamen al ole in e alua ing he comp essi e
s eng h o conc e e. The p esence o po es in he conc e e ma ix e-
duces he solid su ace a ea a ailable o s ess ansmission, po en ially
comp omising he ma e ial’s load-bea ing capaci y. I is c ucial o
conside no only o al po osi y bu also he size, dis ibu ion, and
in e connec i i y o po es, as hese ac o s signi ican ly in luence he
mechanical beha io o conc e e [9].
To p o ide a comp ehensi e analysis, po es we e classi ied in o ou
ca ego ies in Fig. 10: gel po es (<10 nm), la ge mesopo es (10–50 nm),
mac opo es (0.05–10
μ
m), and en ained ai (>10
μ
m) [53].
In pa icula , po es wi h a size in he ange be ween 0.01 and 10
μ
m
ha e a de imen al e ec by weakening he conc e e ma ix, c ea ing
s ess concen a ion poin s, and acili a ing c ack p opaga ion. In
con as , gel po es, wi h a size smalle han 0.01
μ
m, do no ha e a
signi ican impac on comp essi e s eng h. In ac , a small quan i y o
gel po es can be bene icial by imp o ing he wo kabili y o conc e e and
educing sh inkage.
Rega ding he esul s o each ype (Table 4), i was obse ed ha as
he pe cen age o SPS inc eases, he o al po osi y dec eases excep o
he 0.15 % dosage, which is slighly inc ease espec o 0.1 %. In he
di e en anges, he end is simila o ha o o al po osi y. These
indings align wi h obse a ions made wi h a s e eomic oscope (see
subsec ion 3.5), whe e i was assumed ha wi h highe SPS dosage, he
numbe o la ge po es would be educed. This phenomenon sugges s an
expec ed inc ease in comp essi e s eng h. Howe e , i is impo an o
conside o he ac o s ha may in luence po osi y concen a ion, such as
an excess o supe plas icize s, which could lead o an inc ease in po e
size and o al po osi y in pas es, mo a s, and conc e es [24].
3.7. Mechanical p ope ies
3.7.1. Comp essi e s eng h
In his sec ion, he a e age alues o comp essi e s eng h ob ained
om ou epe i ions a e p esen ed. As depic ed in Fig. 11, he a e age
comp essi e s eng h o he conc e e inc eased wi h he ise in SPS
concen a ion. Fo he SPS-0.05 concen a ion, a 0.4 % inc ease o
comp essi e s eng h was obse ed compa ed o plain conc e e, which
p o ed o be negligible. Howe e , in he case o he SPS-0.10 concen-
a ion, he e was a 4.5 % inc ease, while o SPS-0.15, i was 9.5 %
highe compa ed o plain conc e e.
These indings a e di ec ly linked o po osi y. In he case o SPS-0.05,
he inc ease in comp essi e s eng h was impe cep ible because, in he
ange o po es la ge han 1 µm, i was e y simila o ha o SPS-0, as
can be seen in Fig. 10. I is in he case o SPS-0.10 and SPS-0.15 whe e a
mo e signi ican educ ion in po osi y is obse ed in he ange o po es
la ge han 1 µm, especially in he band o po es la ge han 90 µm. This
highligh s he consis ency and co ela ion be ween comp essi e
s eng h esul s and he in e nal po osi y o he ma ix.
3.7.2. Flexu al ensile s eng h
Fig. 12 p esen s he Load-CMOD displacemen cu es o all es ed
specimens (SPS-0, SPS-0.05, SPS-0.10, and SPS-0.15), ob ained om he
h ee-poin bending es s. These cu es p o ide a de ailed ep esen a-
ion o he lexu al beha io , pa icula ly he peak load capaci y, pos -
Table 3
Coe icien s o Eq. (2) and se ing imes a 25ºC.
Mix A b R
2
Ini ial Se [h] Final se [h]
SPS−0.0 −54.11 124.92 0.9531 9.30 13.20
SPS−0.05 −138.70 418.01 0.9836 15.80 20.10
SPS−0.10 −165.20 554.18 0.9643 23.15 28.15
SPS−0.15 −205.10 739.66 0.9877 31.00 36.65
Fig. 7. UHPC hea low o hyd a ion wi h di e en dosages o SPS.
J.D. Ruiz Ma ínez e al.
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Fig. 8. Images wi h hei espec i e 3D modeling o each mix: a-b) SPS-0, c-d) SPS-0.05, e- ) SPS-0.10, and g-h) SPS-0.15.
J.D. Ruiz Ma ínez e al.
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peak so ening esponse, and ene gy abso p ion. As obse ed, he
inco po a ion o SPS leads o an inc ease in peak load and enhanced
pos -peak esis ance, wi h highe SPS dosages exhibi ing a mo e g adual
decline in load, indica i e o imp o ed ac u e oughness [54]. The
CMOD cu es allow o a mo e p ecise e alua ion o he c ack p opa-
ga ion and duc ili y o he ma e ial.
Fig. 13 displays he alues o he p opo ional limi (LOP) ela i e o
he EN 14651:2007 +A1:2008 s anda d [46], se ing as a ep esen a-
ion o he lexu al s eng h o ini ia ion o lexu al c acking, as well as
he esidual lexu al ensile s eng h o all mixes admixed wi h SPS and
hei espec i e s anda d de ia ion.
In all SPS concen a ions, an inc ease in he ini ia ion o lexu al
c acking is obse ed (black squa es in Fig. 13), by 10 % o SPS-0.05,
31 % o SPS-0.10, and 38 % o SPS-0.15. This imp o emen in he
ini ia ion o lexu al c acking is a ibu ed o he educ ion o mac o-
po es deduced om he po osime y esul s (Fig. 10) and because he e
is a highe local ic ion be ween ma ix and ibe s when SPS is added
Fig. 9. P o ile ela ed o EDF images.
Fig. 10. Po e size dis ibu ion o each conc e e wi h di e en SPS concen a ion.
Table 4
To al po osi y (mL/g) and po e ange dis ibu ion (mL/g).
Range SPS-0 SPS-0.05 SPS-0.1 SPS-0.15
>10
μ
m 0.158 0.205 0.126 0.125
10–0.05
μ
m 0.345 0.337 0.334 0.306
0.01–0.05
μ
m 0.100 0.091 0.105 0.159
<0.01
μ
m 0.045 0.006 0.014 0.022
To al 0.635 0.555 0.566 0.593
J.D. Ruiz Ma ínez e al.
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