technical committee on autogenous healing in cementitious materials_tc075b_tcr09
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8/14/2019 Technical Committee on Autogenous Healing in Cementitious Materials_TC075B_tcr09
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Tedmical Ciee Re阿おω Dig Eiti, 91-1ωI C叩yn似⑥2閥均a Co間取IstJtute
Committee Report : JCI・ TC075B
Technical Commttee on Autogenos Heaing匝Cementtous Maerials
Shn-ichi GARASH, Mnoru KUND, Tomoya NSWK
Abstract
91
百le Committee on Autogenous Heaing in Cementitious Meris (chain: Shinichi
gashi, Kzawa University) hs cried out its activiesωreonlze pぉt studies on血e
sef-heng!-reparingncon of concrete over two yes (2007-2008). A surey of 白E
iterature ncuding the atest reserch位ends of the commitee members was conducted with a
prtic叫r focus on由e mechism of sef-heing!repairing, in order to cassi骨粗d dene
the phenomena. The Commitee so hed a workshop/pe discussion during也e nu
convention of JCI in 2008, at which vuabe owedge企om resechers in vrious spheres
ws accumuated, with discussions made on e requred direction of tre s佃dy.
Keywords activated reparing, autonomic heng, crack, natra heaing, repr
technique
Introduc姐onSefheaing of cracks in concre旬is a generic term for phenomena incudng re-hydration
of unhydrated cement, which hs been recoied as a phenomenon for a ong te, as
mentioned by A. M. Nevie1 s‘autogenous heaing.' However, da回accumuaon組d
qutitive evauation have not been sucient for engneers to consider白is phenomenon
也e desi ste. Therefore, it hs not become avabe for desi d use as a method of
repair. JCI Technic Commiton Autogenous Heng n Cementious Mris
(JC・TC075B, chann Shnichi gashi, Kzawa University) hs cied out cvities
to review past studies on sef-heaing!・repairing of concrete over the ast two yes
(20072008). 百e commitee members, who e isted n Table , ∞nduc旬d a iterature
surey incudng ther atest reserch resuts d hed discussions wi the of achievng
也e qutication of sefheaing on vious scaes. Specic弘ese ncude a microscopic
eve (modeng usng cement hydraon modes), mesoscopic eve (evuation on a eve of
constutive modes), d macroscopic eve (utiiz耳ion methods on a concre旬member eve).
At a workshop/pe discussion hed durng the Annu Convention of JCI in 2008, vauabe
owedge of resechers 企om vious eds w accumuated, wi discussions hed
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8/14/2019 Technical Committee on Autogenous Healing in Cementitious Materials_TC075B_tcr09
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S Igahi, M KW児a and T. Nihiwaki ! Tec加ical Cittee Rors 2ゆ Diest Editm, 91-102
1ble : Dra table of conents of e epot
Capter 1 IntroducionCapぬr 2 Sef. heag/repairing peomea ad deosCapter 3 Sef. heag/rep唱iring mecasms and crrent stae of techology
Capter4 Maぬria 即時田皿odels o se. ealing/repairgCapter 5 Eperea evalation of self hea酔epairing e飴ctsCapter 6 Applcaon exampes of sef heag/reparng nctonsCapt泡r7 τeame of sef heag/ep岨rg other 直dsCapter 8 Sef heag peomena of ceamc materas (Specal corbo)Capt泡r 9 JCI wokshop FokaCapter 10 ConclsosAppendx
. Classcaion o phenomena and de自国姐ons otems
93
The Commitee categorzed te concept of self-hengーreparing as shown n Fig. 1組d
Table 3, focusng on respecve phenomena. Tabe 4 gives exples of studies n each
c旬gory. The c蹴go白紙ion nd dierences of mechnisms betw閃ne c蹴goe温e
expled n e following praphs:
‘Recovery' which covers te entire ea shown in Fig. 1 is dened s event in gener
n which least one nion of concrete rωovers by whatever mes. Conventiona
repair/s仕engtenng corresponds to也is while it is expected也at self-heaing・reparing of
concrete det w由is report will be regded s a fesible mes for recovery.
‘Selfheaingrepairng' is demed悩n event n genera in which at lest one nction of
concrete recovers by mechnisms nherenty provided n concrete wi世0ut te need for
rep or s回ng世enng. Note紙‘heaing' d‘rep釦ing' e dierentiated om each oter
as follows: te foner refers to cloggng of cracks by phenomena found in convention
concrete s well suchrehydration of cement d deposion of cacium cbon旬 wheres
e l枕er refers to mens clog crackng by te addition of rtici device s a substitute
for convention repr/s回ng世enng. I oter words ‘heaing' mkes cracng of a
cementitious meria clogged by itself, utiizng its nne mechisms. Addition of a
supplement cementitious materia for nstnce appropri旬 proportion to accelerate
such a crackclogging mechism is aso ncluded in‘heng.世e oter hd,‘reprng'
adds devices such箇microcpsues nd heatgeneratng devices血a e outside of也E
category of conventiona supplementry cementitious materis to imprt a crackclogging
cpability s a new ncon.
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S Igahi, M KW児a and T. Nihiwaki ! Tec加ical Cittee Rors 2ゆ Diest Editm, 91-102 95
Table 4: Study cases corresponding to he classicaon of se-healingrepairing
乃 pe Study case Heangl Ineretlreparmg engieered
仏 Natua heang Re. hydato of esda Heang Ieet
yaed田皿et n ow WICcoceeRe. hydato of cacks fond nhydr ulic scues
[B] Autonoc eag Use ofy as EngieeredECC cotaining ashUse of speca addtve (expaveaddve)Use ofbacea
[C] Acivaed repairi Incusio of icrocapsues, ec RepargUse ofbrite ppe eworUse of heageneraing devces
Use of sapeeory aoysFuso wit oorng techniques
A stated bove,由e scope of‘healing' ncludes two direcons.印e lS craιk clogging by
conventionally own phenomena, such s cement rehydration d CaCÜ deposition n
hydraulic suctures. The other is heng by adding chemic admires d/or
supplement c四entitious ma細胞s,such悩担保psive addive,y錨h,uncured epoxy,
ωconcreteωeact i脂latent po旬ntial,or by includng short bers n concrete to suppress
the widenng of crack wid血s. The latr direction aso ncludes a methoda utilzes bacteria
livng orgisms, having them deposit CaC03 in cracks to clog them 百e foer drection is
dened here s‘na加ra heang,悩
with no tici mes. This corresponds to ea A in Fg. 1.百e latter direction is dened
here s‘autonomic heang, in view of也e ct也at,血ough supplementry cementitious
materials nd/or renforcing bers紅白added to concrete, these have been ∞nvenonly
added to concrete not for self-healing/-repairng but to be in旬a pt of世e s飢re
constutng concæ旬.百e 旬rmautonomic' was adopted ωexpress concretes own hengeect, because the s佐ct町e of concrete itself accelerates clogging of cracks. This corresponds
to ea B n Fig. L‘Autogenous healing is deed as the concept encompassing eas A d
B. I refers ω a phenomenon in genera n which crackng is clogged by
mechisms/capabilities possessed by the sucture of concrete itself, regdls of wheer or
not ay supplementry cementitious materiachemical adm区re is added
In the entre ea of‘recover shown n Fg. 1,e ea outside of e category of
‘healing represents‘reparng.' Area C in也e gure is deedぉ‘activd rep創ngJemphaszng 由e pont紙the healing nction is developed by a stmulus企om outside. Tis
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96 S Igahi, M KW児a and T. Nihiwaki ! Tec加ical Cittee Rors 2ゆ Diest Editm, 91-102
ea includes study cases atempting ωmic clogging of cracks by incorporating something
di島rent om conventiona1 concrete s回Cre,such as concrete w抽 embedded devi∞for
automac repring by a specic igger including rticia1 ones to aively imprting a
selιrepairng eect s a new nction. Specica1y,也is nc1udes the nstnces of embedding mcrocps由s or glass pipesntninge above-mentionrepr mia1s,as well as these
combned wi a heatng device.
In addition since‘autonomic hea1ing' d aivated repa廿ing e investiged in白
se direcon of addng a new釦nction,世e rea nc1uding bo曲目deed with a term
‘engneered he1ng!rep創rng.
3 Examples of se-healing-repaiing31 Natural healg
Fgue 2 shows n exple of natura1 hea1ing in concreぬ ). This is a conぽete specimen
havng aticia1 crackng induced d then eposed t a tida zone enviromnent for 15 yes.
Most cracks with a sm11 width (ound 0.5 m or less have been natura11y heed. The
substces c10gging the cracks re reporedω be primaily et位g旬with needlelke crystas
nd maesium hyoxide.
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s Igi, M. Kunieda nd T Nihiw / Technic Cαnmittee Repor 309-Diget Editi岨, 91-102
a Ettringte and magnesum hydroxide deposting near crackngcourtesy of H. Hamada
" CO i n the
0C032ーキ
\ Water
(b) Mecansm ofnatural eaing
Figu : Exmpl of nul hlng in hydulic sucus
3. Auonomic hng
97
Concrs contaning n xpnsiv addiv 3
) nd y ash4) noducd in hs scon as
匂pical xpls of auonomic halng.
Figu 3 shows cogging of cracks n n auonomic-halng concr conanng n
ansv addiiv a slighy hgh dosag血n usu I has bn conmd血a a crack
widh of up o 0 m cn b suciny cloggd by姐g of 28 days Aciv rsrch s
conducd on曲s p of concrt wi aim of rducng wa lakag by cack cloggng
Figu 4 shows an xpl of auonomchaing ∞ncr ulzng susand
hydaon of y ash. Ths sudy was conducd as a join rsch by h Hokkado NorhRgiona Buldng Rsach Insu, Murorn Insu ofcnology, and ohr n副知ions
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98 S. IgarashiラM. Kunieda and T. Nishiw北i / Technical Commitee Repors 2009 - Digest Editionラ91102
This tpe of healing is also characterized by the cracks to be healed - microcracks
induced by ost daageラwhich are not as lage as macroscopic cracks due to bending.
Autonomic healing of cracks aer undergoing deterioration due to企eezing d awing
action has been evaluated based on compressive streng, relative dynic modulus of
elasticit, carbonation dep, pore volumeラad visual cracking information. Recuring for
four weeks at has been carried out to enhace y ashヲs potential capability of autonomic
healing, proving a high autonomic healing eect of y ash cement.
Figure 3: Example of healing of a crack with a width of around 04 mm
(courtesy of Á. Hosoda)
Durabiity factor 7% Durabiity factor 9%
I g dg g-sg zz s, sv zg s sS ks z- ss g gs
(FAreplacement ratio of 1 to 15% with a W/C of 5 to 55%)
Figure 4 Combination of freeze-thaw deterioration and autonomic healing5
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s Igarashi, M. Kieda d Nishiwaki I Technical C叩niee Repα 2叩9 -Dige泣Et叩, 91-102 99
33 Activated repairing
Concree in which a glass pipe en伺psulating a epai material nd a hea-geneating
device e embedded6) as sho Fig. 5 is a epresenative exmple of activated repairing.
The occrence of a crack aivates a mechnism白紙selecively heas he紅ea ner the crack, thereby auomatically suppying e epai mateial企om te pipe embedded in the concree
material
New crack due to re-Ioading
Figure 5: Actvated repairng by supplying a repair material
(courtesy ofT Nishiwak)
4. Summary of experimental nvestigation
Tale 5 gives epresentave exmples of exising meods of inoducing dmge nd
ev山富士ing selfhealing・repairing, as wel a evalu富士ion indices. Snce selιheingrep即時
is generay reevnt to ‘cracks,' most expeiments induce tensie o bending cracks
concree to a specied crack widh. hen, te concrete is recred,組d subjeced o s出il
tests to con批estorion of批帥ng血 rigidity, and absorbed energy (te蹴a under
働oaddispacement cuet9).刀ere e so mny exmples which micocrcks wiin
concree induced by企eezing nd thawing ωt e c10gged by autonomic heing, for ins旬nce,
which is evuated by relaive atios of dynmodulus of elぉiciザ 10) d ose in which
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100 S Igahi, M KW児a and T. Nihiwaki ! Tec加ical Cittee Rors 2ゆ Diest Editm, 91-102
chnges n the water permeability accordng to chngng crack width are measured 3, 11)
Exmples of evaluatng the resistnce to mass sfer伽oug clogged cracks other 世
w旬r incude也ose evalu組ng也e resistce ω chloride ion仕sfer12. However mo唱t of
these nvestigaons currenty reman on a research level Furthermore it is also hoped白紙self-healng of other tpes of dage will be nvestigated d that eistng nondes佐ctive test
methods will be applied to由e evalution of selfhealing
Table 5: pes of damage, resto叫on mechanisms, and evauaon
mehods/indces relevant o sel-healng (exampes)
Method of nducing damage Lang tes {ense, exrreezand thawimtes
Restoaton mechasm (shown above) Natal ealngAtonomc heng (Fly as epansveaddtve y ash + sot直be eocemen ec.)Acvaed epang {Resn capse glassppe + epaÌ mateaÙ
Evalaon metod/ndex McrosopeWater permeabiytasoc plse veocyCaplly absoponDepth of code on penetaonFe sengthAbsobed enegyRgtyReatve dynamc mods
5. Outline ofworkshop
A workshop tited ‘the Cutngedge niques of Concrete Selfreparing' which was
held on the second day of the JCI nual Convention at Fukoka in 008 whig ly
success with participts accordngω也e x utiv r (see Fig. 6
At rst the committee charman Shin-ichi Igarashi of Kanawa University nodu∞d也e purposes d backound of也mmitteed the workshop. Then the secret Mnoru
Kunieda of Nagoya University suaed也e discussions at也e commitee ncuding the
国get scope d demitions of terms ぽ由民o血er committee members in位。du∞d
cuttngedge nformaion related to selfhealing/repairing as foll日明:
Hidenori Hada of Kyshu University reported natral healng found in mne s甘uctures;
ro Sagawa ofNi自u Cement repo巾d on auωnomic heang ulng世e pozolanic
reaction of y ash kira Hosoda of Yokoha National University d ・hoA
of也eUniversity of Tokyo reported on autonomic heangncrete using e却nsive additive nd
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S. Igarashi, M Kieda ad T. Nishiwaki I Teclicl Cαnmiee R叩αs 3)09-D沼田t Editio, 91-102 101
Tomoya Nishiwaki of Yamagaa Universiy introduced s加dy cases on self-repairing concree
desied o go白rough acvaed epairing using glass pipes and heageneraing devices. This
bieng session was foowed by a panel discussion coordinaed by Pro Hirozo Mihashi of
Tohoku Universi臥wih白e following pneliss: Prof. oyoaki Miyzawa ofKyoo Universiy,
Assoc. Pro oshih Kishi of 白e Universiy of okyo, ad Dr K位uo Yamada of 白e
Cenal Reserch Insie, aiheiyo Cemen. In he discussion niiaed by Prof. Mihshi, he
peiss alked abou he backounds o血eir sdy d new ideas, expecaion for he
esablishmen of guideines based on quiative evaluaion, d e imporace of conrol,
acivey exchging views incuding quesions om picips
a Panelists (b) Panelists
(c) The audience
Figure 6: JCI workshop in Fukuoka
6. Summary
A saed above, e review of he curren sae of selfhealing/ーrepairing caied maers
necessy for puing由is echnoogy o pracical use JCI plas o organiz怠a new commiee
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102 S Igahi, M KW児a and T. Nihiwaki ! Tec加ical Cittee Rors 2ゆ Diest Editm, 91-102
on由e systeatzation of self-he1ng technology for ceentious aeria1s chared by Prof.
Shn-ichi Igashi ofKnawa University for 2009 d 2010 to deve1opent11y te over
由e activities of由e present cottee百e new coittee pcully ntends t sit
resech infoation d acculate d翻on selfhea1ing/repairing technology
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