Corrosion and Protection of Steel Reinforced Concrete

7/23/2019 Corrosion and Protection of Steel Reinforced Concrete

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CORROSION AND PROTECTION OFSTEEL

REINFORCED CONCRETE

PROVIDED BY: EMAD BEHDAD

LECTURER: PROF.SHAMS

CORROSION AND

PROTECTION OF STEELREINFORCED CONCRETE

PROVIDED BY: EMADBEHDAD

LECTURER: PROF.SHAMS


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OUTLINE

INTRODUCTION CORROSION PROCESS

TYPES OF CORROSION CAUSES OF CORROSION

PROTECTION METHODS CONCLUSION


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What is Corrosion o St!!"# ASTM terminolog !" #$% &e'ne( )orro(ion *( +t,e

),emi)*l or ele)tro),emi)*l re*)tion -eteen *m*teri*l/ 0(0*ll * met*l/ *n& it( en1ironment t,*t

2ro&0)e( * &eterior*tion o3 t,e m*teri*l *n& it(2ro2ertie(.4 For (teel em-e&&e& in )on)rete/)orro(ion re(0lt( in t,e 3orm*tion o3 r0(t ,i), ,*(to to 3o0r time( t,e 1ol0me o3 t,e origin*l (teel

*n& none o3 t,e goo& me),*ni)*l 2ro2ertie(.Corro(ion *l(o 2ro&0)e( 2it( or ,ole( in t,e (0r3*)eo3 rein3or)ing (teel/ re&0)ing (trengt, )*2*)it *( *re(0lt o3 t,e re&0)e& )ro((5(e)tion*l *re*.


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Electrochemical process of steel

corrosion in concrete


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Volumetric change


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Ca, Na, K hydroxides inhydrated cement raise the pHto ~13.

! dense protecti"e ferricoxide #$e%&3' passi"e film

forms around thereinforcement

(his passi"e film stops irondissolution, and is sta)le atpH *1+

R!inor$!%!nt Prot!$tion &'

Passi(! Fi"%

P*((i1e 'lm &e1elo2( on t,e -*r (0r3*)

2H 6#7


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Y!s i:

!a) Con$r!t! is a"*a's +r', th!n th!r! is noH-O to or% rst. A"so a//r!ssi(! a/!nts

$annot !asi"' +i0s! into +r' $on$r!t!.1&) Con$r!t! is a"*a's *!t, th!n th!r! is noo2'/!n to or% rst.

1$) Catho+i$ 3rot!$tion is s!+ to $on(!rt

a"" th! r!inor$!%!nt into a $atho+! sin/ a&att!r'. This is not !as' to i%3"!%!nt&!$as! ano+i$ %!sh is !23!nsi(!, an+ thist!$hno"o/' is not !as' to insta"" an+ %aintain


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Can we avoid corrosion?

No, not entirely:Concrete is not usually under ater or

continuously dry. Aggressive agents such

as carbon dioxide! de-icing agents and"orsea ater can diffuse into the best of moist

concrete! and corrosion ill eventually

result.


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CAUSES OF CORROSION INCONCRETE


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COMMON CORROSION TYPES4) Cr!(i$! Corrosion

Cre1i)e )orro(ion i( * lo)*li8e& 3orm o3 )orro(ion0(0*ll *((o)i*te& it, * (t*gn*nt (ol0tion on t,emi)ro5en1ironment*l le1el. S0), (t*gn*ntmi)roen1ironment( ten& to o))0r in )re1i)e( !(,iel&e&*re*(%. O9gen in t,e li0i& ,i), i( &ee2 in t,e)re1i)e i( )on(0me& - re*)tion it, t,e met*l.

O9gen )ontent o3 li0i& *t t,e mo0t, o3 t,e )re1i)e,i), i( e92o(e& to t,e *ir i( gre*ter/ (o * lo)*l )ell&e1elo2( in ,i), t,e *no&e/ or *re* -eing *tt*);e&/ i(t,e (0r3*)e in )ont*)t it, t,e o9gen5&e2lete& li0i&.


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Crevice Corrosion of Rebar as So!e

Si!ilarities wit" #illifor! CorrosionThe head of the advancing filament becomes

anodic! ith a lo p# and a lack of oxygen!

as compared ith the cathodic areaimmediately behind the head here oxygen

is available through the semipermeable

film. Corrosion proceeds as the cathode

follos behind the anodic head (from

Corrosion $asics %AC&).


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-) Pittin/T,eorie( o3 2*((i1it 3*ll into to gener*l )*tegorie(/ one -*(e& on *&(or2tion *n&

t,e ot,er on 2re(en)e o3 * t,in o9i&e 'lm. Pitting in t,e 3ormer )*(e *ri(e( *(&etriment*l or *)ti1*tor (2e)ie(/ (0), *( Cl5/ )om2ete it, O< or OH5 *t (2e)i')

(0r3*)e (ite(. B t,e o9i&e 'lm t,eor/ &etriment*l (2e)ie( -e)ome in)or2or*te&

into t,e 2*((i1e 'lm/ le*&ing to it( lo)*l &i((ol0tion or to &e1elo2ment o3

)on&0)ti1e 2*t,(. On)e initi*te&/ 2it( 2ro2*g*te *0to5)*t*lti)*ll *))or&ing to t,e

gener*li8e& re*)tion/ M=n = nH M!OH%n = nHCl/ re(0lting in

*)i&i')*tion

o3 t,e *)ti1e region *n& )orro(ion *t *n *))eler*te& r*te !M=n *n& M *re t,eioni)

*n& met*lli) 3orm( o3 t,e )orro&ing met*l%.


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Air-orne/ m*rine/ in&0(tri*l/ gro0n&*ter/ )*(t5in

Cl? )*n 2enetr*te t,ro0g, t,e 2*((i1e 'lm

At Cl5 6 +t,re(,ol&4/ 2*((i1e 'lm -re*;( &on/)orro(ion initi*te(Cl5 +t,re(,ol&4 1*l0e i( t2i)*ll @.@$ - t o3

)on)rete !@.@


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Ca1OH)- 5 CO- 6 CaCO7 5 H-O


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EFFECT OF CARBONATIONIt )*n )*0(e (o3t (0r3*)e/ &0(ting *n&

)olor

),*ngeIt re&0)e( 0*lit )on)reteIt re&0)e( t,e )on)rete *-ilit to

2rote)trein3or)ement 3rom )orro(ion !in *ne92o(e&en1ironment%

It ill re(0lt in *&&ition*l (,rin;*ge in


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DETECTIN" CARBONATION De2t, o3 )*r-on*tion )*n -e &ete)te& 0(ing

*n in&i)*tor.

A ),emi)*l (0), *( P,enol2,t,*lein (2r*e&on to 3re(,l -ro;en )on)rete.

Are*( rem*ining *l;*line ill t0rn in * -rig,t20r2l52in; )olor.

C*r-on*te& *re*( o3 )on)rete ill rem*in0n),*nge& in )olor.


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!8 !8

Cl-Cl-

R!&ar!8 !8

R!&ar

F! F!55

5(! Ions $ve Ions


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Degree

ofCorrosi

on

Time

I

Initiation Propagation(corrosion)

Critical chloridethreshold

Migration of chlorides, H20

and O2into the concrete, no

corrosion and no damage toconcrete

Corrosion of the steelreinforcement and

cracing and!or spallingof concrete

Reinforcing steel corrosion

ClCl-

ClCl-


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Cl-Cl- Cl

-

Cl-Cl-

Cl-Cl-Cl-

Cl-Cl-

Cl-

Cl-

..

.

.

. .

.

.

.

.

.

.

.

.

.

.. .

.

. .

.

...

..

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.

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..

.

.

.

.

.

..

..

.

.

.

..

.

.

.

.

..

.

. ..

..

.Electrolyte

Cl- Cl- Cl-

Cl-Cl-Cl-

Cl-Cl-

Cl-

Cl-

Cl

Cl-Cl-

Cl- Cl-

Cl-

Cl-

Cl

Cl-Cl-

Cl- Cl- Cl-

Corrosion = Iron + Oxygen + MoistureEither

the pH falls due to car)onation or other chemicals

chlorides reach the steel a)o"e the threshold concentration

an electrical charge destroys the natural protection of the steel Electrons flo and ions migrate

-ust expansion causes cracing

-apid deterioration

/palling

pH *~1+

!node CathodeCathode

e0 e0

Moistr!O2'/!nIron


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"palling

Cracs

#ith$%st"taining

$e&arloss

Delamination


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%bandoned Electric Pole


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9ISH ISLAND


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BANDAR ABBAS


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),lori&e in&0)e&rein3or)ement)orro(ion in

)on)rete e92o(e&to (e**ter

Corro&e& re-*r 3rom )r*);e& )on)reteo3 * 2*r;ing (tr0)t0re e92o(e& to&ei)ing (*lt(


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Rein3or)e& (teel in )on)rete

)r*);ing


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CORROSION PREVENTION

METHODSREBAR COATIN"

SCARIFIED PATCHED DEC AAITS

ANODE MESHFLY ASH

HOT5DIP "ALVANIIN"

IRELESS SENSOR FOR MONITORIN"CHLORIDE IN CONCRETE

INHIBITORS


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REBAR COATIN" A+(anta/! o !3o2' $oat!+ r!&ar

Th! $oatin/ has stron/ a+h!si(! or$! to th! st!!".

Th! $oatin/ has /oo+ $h!%i$a" sta&i"it'.

Th! $oatin/ has /oo+ t!na$it' an+ *!ar a&i"it'. Th! $oatin/ has hi/h ins"ation an+ anti8$atho+!

+!$o%3osa&i"it'.

Th! $oatin/ has *i+! ran/! t!%3!ratr! a+a3tation.

Th! $oatin/ has hi/h a+h!si(! or$! *ith th! $on$r!t!.

Pro+$ts ha(! n! Ph'si$a" Pro3!rt'.

Us!+ in th! &i"+in/ *ith hi/h +!%an+ an+ n+!r th!$orrosi(! En(iron%!nt, it $an "!n/th!n th! s! "i! o th!&i"+in/ or %or! th! ;< '!ars.


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EPOY COATIN" PREVIE MODEL


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EPOYGCOATED BARSAno+!

Re&0)e( *no&e

*re*In)re*(e(t,re(,ol&

Catho+!

Re&0)e( )*t,o&i) *re*

E"!$tri$a" Conn!$tion Ele)tri)*l 2*t, -eteen

*no&e *n& )*t,o&e Ma=!s ioni$ 3ath*a' "on/er

Ioni$ 3ath

REDUCEDCORROSION


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t,erm*ll (2r*e& )o*ting( o3

n *n& Al/ )om-*t )orro(ion For *tmo(2,eri)/ -0rie&/ *n& m*rine en1ironment )orro(ion

2rote)tion/ n !TS%/ Al !TSA%/ *n& t,eir *llo( ,*1e 2ro1en t,*tt,e 2ro1i&e long term )orro(ion 2rote)tion *n& o0t2er3orm mo(t*ll ot,er met,o&(.

Ano&i) !TSJTSA% met*l )o*ting( *22lie& to (teel )*t,o&e( !moreno-le t,*n n or Al%/ *re re3erre& to *( )*t,o&i) or (*)ri')i*l2rote)tion )o*ting ((tem(.

T,e(e t,erm*l (2r* )o*ting( 2ro1i&e )orro(ion 2rote)tion -e9)l0&ing t,e en1ironment !or ele)trolte% *n& *)ting *( * -*rrier)o*ting !li;e 2*int(/ 2olmer(/ *n& e2o9ie(%/ -0t 0nli;e t2i)*l

-*rrier )o*ting( t,e *l(o 2ro1i&e (*)ri')i*l *no&i) 2rote)tion.


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>in$ an+ ?in$ a""o's ar! a"so s3ra'!+ +ir!$t"' onto$on$r!t! to 3rot!$t th! st!!" r!&ar *ithin

Ar) (2r*ing o3 8in) on * )on)rete-ri&ge 2ier in t,e Flori&* e(. In t,i()*(e t,e 8in) *)t( *( (*)ri')i*l *no&e/

*lt,o0g, it i( more 3re0entl 0(e& inim2re((e&5)0rrent ((tem(. T,reeim2re((e&5)0rrent 8in) ((tem( ,*1e*lre*& -een in(t*lle& - t,e Mini(tro3 Tr*n(2ort*tion o3 Ont*rio in Toronto

S*)ri')i*l )*t,o&i) 2rote)tion o3 (teelin )on)rete - t,erm*l 8in) (2r*ing


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FLY ASH 0(ing * Fl A(, )on)rete it, 1er lo 2erme*-ilit/ ,i),

ill &el* t,e *rri1*l o3 )*r-on*tion *n& ),lori&e( *t t,e le1elo3 t,e (teel rein3or)ement.

Fl A(, i( * 'nel &i1i&e& (ili)* ri), 2o&er t,*t/ in it(el3/gi1e( no -ene't ,en *&&e& to * )on)rete mi9t0re/ 0nle(( it)*n re*)t it, t,e )*l)i0m ,&ro9i&e 3orme& in t,e 'r(t 3e&*( o3 ,&r*tion. Toget,er t,e 3orm * )*l)i0m (ili)*,&r*te !CSH% )om2o0n& t,*t o1er time eKe)ti1el re&0)e()on)rete &iK0(i1it to o9gen/ )*r-on &io9i&e/ *ter *n&),lori&e ion(. B re&0)ing ion &iK0(ion/ t,e ele)tri)*lre(i(t*n)e o3 t,e )on)rete *l(o in)re*(e(


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CATHODIC PROTECTIONIm2re((e& )0rrent !*)ti1e%

S*)ri')i*l *no&e !2*((i1e%


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TITANIUM ANODE MESH%& TYPIC%''Y %TT%CE( TO TE CONCRETE S)R#%CE %N(

TEN ENC%PS)'%TE( IN CEMENTITIO)S M%TERI%'S&

*+ E%SI'Y CON#ORMS TO TE STR)CT)RE EOMETRY&

C+MOST )SE( IMPRESSE( C)RRENT %NO(E #OR CONCRETE&


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Mi9e& Met*l O9i&e *)ti1*te& Tit*ni0m Ano&e( in t,e 3orm o3 *ri--on me(, )*n -e in(t*lle& in )lo(e 2ro9imit *n& 2*r*llelto t,e rein3or)ement -*r( !re-*r%.

MMO Ri--on Me(,


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1. Simple to Install.

2. No Power Supply Needed.

3. No Wiring or Conduit.

4. No Long-Term Monitoring or Maintenance


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Conventional Patch Repair


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Embedded inc !node "or Patch Repair


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CATHODIC PROTECTION

SACRIFICIAL ANODE


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REFRENCES Concrete Society Technical Reports TR 36 and 37


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.)orro)ell.)o.0;


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Documents

Corrosion and Protection of Steel Reinforced Concrete