Presented by: Derek Zaccheo,

Steven Kreeley,

and Gary Reiff

CORROSION OF STEEL REINFORCEMENT

IN CONCRETE AND MINIMIZATION

PROBLEM STATEMENT

Corrosion a major issue in

reinforced concrete structures

Protective coatings on rebar within

concrete matrix

Chloride attacks, carbonation and

alkaline reserve losses mainly

responsible

Volume of corrosion products

exceeds volume of steel, creating

tensile stresses

Tensile stress leads to cracking,

spalling, potential failure of

structure

CORROSION MECHANICS

Carbonation and/or chloride induced corrosion primary causes

Both causes are functions of electrochemical processes

CARBONATION-INDUCED

PROCESS

CHLORIDE-INDUCED

PROCESS

CORROSION MECHANICS (CONT.)

Carbonation Depth Factors:

Cover Thickness

Carbonation Resistivity

Effective CO2 Diffusion Coefficient

CO2 Binding Capacity

Curing Condition

Age

Cement Type

Cement Composition

Calcium Oxide Content

Wetness Time

Ambient Temperature

Relative Humidity

Environmental Conditions

CO2 Surface Concentration

Carbonation depth within concrete influences amount of resulting

corrosion

CORROSION MECHANICS (CONT.)

Chloride attacks typically in

marine environments

Carbonation/Chloride

induced corrosion avoided

with epoxy coated rebar

Epoxy Advantage: safeguards

against generalized corrosion

Epoxy Disadvantage: stil l

prone to localized corrosion

and microcracking

EFFECTS OF CORROSION

Reduction of rebar cross section

Reduction of rebar load capacity

Increase in volume of corrosion product will cause

expansion, cracking, and spalling

CORROSION MITIGATION (MEMORY ALLOYS)

Memory alloys can be used

as rebar instead of

traditional steel

Highly resistant to slowly

occurring corrosion

Nickel-Titanium alloy (NiTi)

typically used

Corrosion rate a function

of the metals used in the

alloy

CORROSION MITIGATION (FIBERS)

Fibers act as a safeguard

between the concrete matrix

and the encased rebar

Typically polypropylene (PP),

polyvinyl alcohol (PVA), and

hooked-end steel fiber used

Responsible for transport of

corrosive elements

Hooked-end steel fiber will

cause corrosion first

generates localized corrosion

of the fiber itself

CORROSION MITIGATION (CONCRETE COVER)

Concrete cover refers to minimum distance

from member face to rebar

More difficult for chloride ions to reach

rebar

Aided by use of admixtures:

Cathodic Inhibitors - form insoluble film on cathodic

surfaces (effective)

Anodic Inhibitors - form insoluble film on anodic surfaces

(more effective)

Organic Inhibitors - block cathodic AND anodic absorption

reactions from occurring on rebar (most effective)

NEW AND DEVELOPING CORROSION

CONTROL TECHNIQUES (HYFRC)

New hybrid fiber reinforced

concrete (HyFRC) delays

cracking up to strains

surpassing those of

conventional steel rebar

Consistently outperforms

traditional plain/reinforced

concrete

Can be used with traditional

rebar

NEW AND DEVELOPING CORROSION CONTROL

TECHNIQUES (ADMIXTURES )

Includes the following:

Silica fume – counteracts

penetrating chlorides and Ca(OH)2

Latex – minimizes pores

Methylcellulose – similar effects as

silica fume, but not as significant

Carbon Fibers – decreases electrical

resistivity of concrete (should be

used with silica fume)

All are easy to use and cost -effective

NEW AND DEVELOPING CORROSION CONTROL

TECHNIQUES (FRP)

Fiber-reinforced polymers (FRPs)

used to mitigate corrosion AFTER

member is affected

Carbon or glass fibers used:

Carbon more typical despite

higher initial cost (performs

better)

Manufactured as plates or

wraps to cover

longitudinal/shear

reinforcement

Wraps most commonly

used to simulate anodes

CURRENT GAPS IN RESEARCH

Use of environmentally friendly

coatings

How to measure degradation

and lifespan of rebar coatings

Industrial knowledge of epoxy

coatings

How to stop localized

corrosion

How to replace coatings

RESEARCH PROPOSAL

Continue research on behavior of

environmentally friendly coatings

in accordance with EPA

regulations

Create models that simulate

coating decay for various

environmental conditions

Use of NDE testing and improved

versions

Utilize code to improve lifespan

calculations

CONCLUSION

Two types of steel reinforcement

corrosion:

Chloride-induced

Carbonation-induced

Epoxy coatings great protective

measure (but potential localized

corrosion)

Different fibers, memory alloys,

admixtures, and FRPs aid in mitigation

Corrosion a fundamental key to

determine structural l ifespan

REFERENCES

[1 ] Blunt J , Jen G , Oster tag C.P. Enhanc ing corros ion res is tance o f re in forced concre te

s t ructures w i th hybr id f iber re in forced concrete . Corros ion Sc ience 2015; 92 ; 182-191 .

[2 ] Facundo Almeraya, J . M. B . , Andres A. Torres Acosta , Ci t la l l i Gaona Tiburc io (2012) .

"Corros ion in Re in forced Concrete ." In te rnat ional Journal o f Corros ion , 2012(1) , 1 .

[3 ] Federa l H ighway Admin ist ra t ion , U .S. Department of Transpor tat ion . Corros ion

Protect ion - Concrete Br idges 1998; 2 .

[4 ] Fu X , Chung D.D.L . E f fect o f corros ion on the bond be tw een concrete and stee l rebar.

Cement and Concrete Research 1997; 27 ; 1811-1815 .

[5 ] Gadve Sangeeta , Mukher jee Abhi j i t , Ma lhotra , S .N . Corrosion Protect ion o f F iber -

Re inforced Polymer -Wrapped Re in forced Concrete . ACI Mater ia ls Journal 2010; 107 .4 ; 349-

356.

[6 ] Hou J iangyuan, Chung D.D.L . E f fect o f admix tures in concrete on the corros ion

res is tance o f s tee l re in forced concrete . Corros ion Sc ience 2000; 42 ; 1489–1507 .

[7 ] Kim B, Boyd A.J . , Lee J .Y. E f fect o f t ransport proper t ies o f f iber types on s tee l

re in forcement cor ros ion . Journal o f Compos i te Mater ia ls 2010; 45 ; 949-959.

[8 ] Ko leva , D .A. , Guo Z . , van Breugel K . , de Wi t J .H .W. Micros tructura l proper t ies of the bulk

matr ix and the s tee l /cement paste in ter face in re in forced concrete , mainta ined in

condi t ions o f corros ion and cathodic protect ion . Mater ia ls and Corros ion 2010; 61; 561-

567 .

REFERENCES (CONT.)

[9 ] Nat ional Mater ia ls Advisory Board , D. o . E . a . P. S . , Na t ional Research Counci l (2011) .

"Corros ion Research Grand Chal lenges ." Research Oppor tun i t ies in Corros ion Sc ience and

Engineer ing , 39 -52 .

[10] Rondel l i G ianni . Corros ion res is tance tests on NiTi shape memory a l loy. Biomater ia ls

1996; 17 ; 2003-2008 .

[11 ] Sw amy, R. N . (1988) . "Epoxy Coated Rebars The Panacea for Stee l Corros ion in

Concrete . " Construct ion and Bui ld ing Mater ia ls , 3 (2 ) , 86 -91 .

[12] Y. Zhou, B . G . , K . Wi l l iam, A. At ta r (2015) . "Carbonat ion - Induced and Chlor ide - Induced

Corros ion in Rein forced Concre te S tructures . " Journal o f Mater ia ls in C iv i l Engineer ing ,

27(9) , 1 -17 .