technical committee on autogenous healing in cementitious materials_tc075b_tcr09

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



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.



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



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.



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



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



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




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



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




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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