PRESENTED AT NATIONAL BRIDGE PRESERVATION PARTNERSHIP CONFERENCE ORLANDO, FLORIDA 2014 AUTHORS ROBERT WALDE, SURTREAT HOLDING, LLC PRESENTER RICH LAMPO, U.S. ARMY CORPS OF ENGINEERS RESEARCH LABORATORY DAVID STEPHENSON, US ARMY CORPS OF ENGINEERS RESEARCH LABORATORY JIM NICHOLS, NASA, KENNEDY SPACE CENTER
Cement Chemistry Porosity –Cement Phase 20% (W/C 0.5) – Penetration of water, air (oxygen and carbon dioxide), Chlorides (CIˉ), other. Alkalinity – pH 13 – Hydroxyl ions (OHˉ) – Inhibit steel corrosion. Carbonation - Reduce pH – Ca(OH)2 + CO2 → CaCO3+H2O pH – 13 to pH – 8
Reinforcing Steel Corrosion Reinforcing Steel Corrosion – Major Cause of Concrete Structure Failure Steel Corrosion Mechanism and Impact • • • •
Electrochemical oxidation process Inhibited by cement alkalinity and cover Accelerated by cement chloride, air and moisture content Types of corrosion Micro cell – same rebar Macro cell – different rebar Uniform – exposed steel Pitting – most common
Feo
Fe++ + 2e-
Anodic cell
H2O + O
2OH-
Cathodic cell
Feo + H2O + O Fe2O3
Fe(OH)2 + 2eExpands
Equilibrium cell
causing concrete delamination and spalling
Corrosion Process on Surface of Steel
TYPES AND MECHANISMS OF MIGRATORY CORROSION INHIBITORS INORGANIC TYPE
MIGRATE IN THE IONIC PHASE FUNCTION AT THE ANODIC CORROSION SITE CHEMICAL TYPES ARE SILICATES AND NITRITES
ORGANIC TYPE MIGRATE IN THE VAPOR PHASE FUNCTION AT BOTH ANODIC AND CATHODIC SITES CHEMICAL TYPES ARE AMINE CARBOXYLATES AND AMINE ALCOHOLS
Reinforced Concrete Micro Structure
METHODS FOR UTILIZING MIGRATORY CORROSION INHIBITORS SURFACE APPLIED ON REINFORCED CONCRETE
Inorganic and organic types used ADDED TO CONCRETE AND SHOTCRETE MIX Inorganic and organic types used DIRECT APPLICATION ON STEEL Organic type dissolved in oil INDIRECT APPLICATION ON STEEL Organic types placed in enclosed space or on packaging ADDITION TO STEEL SURFACE COATING Organic type added to coating formulation
APPLICATION OF MIGRATORY CORROSION INHIBITOR ON BRIDGE DECK
MEASUREMENT OF CORROSION RATE AND DEGREE ELECTRO-PHYSICAL METHODS DIRECT CORROSION CURRENT FLOW FROM ANODE TO CATHODE ASTM G109 MEASURES MACRO-CELL CURRENT INDIRECT MEASUREMENT OF CORROSION CURRENT BY POLARIZATION RESISTANCE Icr =Vp/Pr GALVAPLUSE INSTRUMENT HALF-CELL POTENTIAL ASTM C876-09 MEASURES POTENTIAL FOR CORROSION OR DRIVING FORCE FOR CORROSION IF CONDITIONS FOR CORROSION EXIST. DIRECT OBSERVATION OF PROTECTIVE COATING SURFACES DEGREE OF CREEP FROM X SCRIBED AREA ASTM D1654 SCORE ON SCALE OF 10 TO 1 DEGREE OF SURFACE RUST ASTM D610 SCORE ON SCALE OF 10 TO 1
GALVAPLUSE CORROSION RATE MEASUREMENT
CORPS OF ENGINEERS OKINAWA BRIDGE AND GIRDER RESTORATION PROJECT USING SURFACE APPLIED MIGRATORY CORROSION INHIBITORS STRUCTURE TYPES Fuel depot patrol bridges Warehouse ring girders AGE OF STRUCTURES Built in the 1950’s REBAR CORROSION CONDITION Carbonation front has reached the rebar level Concrete spalling exposed rusty rebar SURFACE APPLIED MIGRATORY CORROSION INHIBITORS APPLIED Inorganic/anodic /silicate type Organic/anodic/cathodic/aminecarboxylate type Application Rates 100SF/gal
Initial Conditions
1 ft.
Structures were experiencing significant rebar corrosion prior to rehabilitation. Corrosion appeared to be due to carbonation of the concrete rather than chloride-induced corrosion 12
Initial Conditions Ring girder of warehouse at Naha Port
Girder shows signs of deterioration due to rebar corrosion and general breakdown of the concrete cement structure. Spalling, efflorescence, delamination, rust stains and other common signs of concrete failure.
13
Culvert Bridge
BEFORE AND AFTER APPLICATION OF CORROSION INHIBITOR DEGREE OF REBAR CORROSION
CHANGE IN EXPECTED TIME FOR CORROSION DAMAGE BEFORE AND AFTER APPLICATION OF CORROSION INHIBITORS 14
-
Ring Girder Degree of Rebar Corrosion Before and After Application of Corrosion Inhibitor System
Probability of Concrete Failure Due to Rebar Corrosion Before and After Application of Corrosion Inhibitor System
15
CORROSION RATE MEASUREMENTS ON REINFORCED CONCRETE BEAM BEFORE AND AFTER APPLICATION OF MIGRATORY CORROSION SYSTEM ON CONCRETE SURFACE MIGRATORY CORROSION SYSTEMS
Organic, Duel Function, Vapor Phase Inhibitor Applied First At 100SF/Gal Of Formulated Product Anodic Ionic Phase Migratory Inhibitor Applied Second At 100SF/Gal Of Formulated Product CORROSION RATE IN MICROMETERS OF STEEL LOST PER YEAR BY CONVERSION OF CORROSION CURRENT IN MICROAMPS PER CM2 BEFORE APPLICATION JANUARY 2007 MEDIAN CORROSION RATE AVERAGE CORROSION RATE
AFTER APPLICATION JULY 2007 JULY 2010
41
6
5
61
23
14
CORROSION RATE MEASUREMENTS ON REINFORCED CONCRETE BRIDGE BEFORE AND AFTER APPLICATION OF MIGRATORY CORROSION SYSTEM ON CONCRETE SURFACE MIGRATORY CORROSION SYSTEMS
Organic, Duel Function, Vapor Phase Inhibitor Applied First At 100SF/Gal Of Formulated Product Anodic Ionic Phase Migratory Inhibitor Applied Second At 100SF/Gal Of Formulated Product CORROSION RATE IN MICROMETERS OF STEEL LOST PER YEAR BY CONVERSION OF CORROSION CURRENT IN MICROAMPS PER CM2 BEFORE APPLICATION JANUARY 2007 MEDIAN CORROSION RATE AVERAGE CORROSION RATE
30 37
AFTER APPLICATION JULY 2007 JULY 2010 8 13
7 7
NASA/KSC JOINT R&D EVALUATION OF TWO NEW MIGRATORY REBAR CORROSION INHIBITORS IN 1996 MIGRATORY CORROSION INHIBITORS EVALUATED
Inorganic Water Soluble Anodic Type Applied At100SF/Gal Organic Alcohol Soluble Anodic/Cathodic Type Applied At 100SF/Gal
TEST METHOD USED
Macro-cell Designed To Measure Half-cell Potential and Corrosion Current Design And Method Similar To ASTM G109 Chloride Activated Rebar (Anodic State) At 1 and 2 Inches From Surface Cathodic State Rebar 5 Inches From Surface Half-cell Measured Through Ports In Test Block
NASA/KSC JOINT R&D EVALUATION OF TWO NEW MIGRATORY REBAR CORROSION INHIBITORS IN 1996 PERFORMANCE RESULTS Inorganic Anodic Ionic Migratory Inhibitor REBAR
FRESH CONCRETE
DEPTH
Potential Current
CORROSION ACTIVE Potential Current
60 DAYS LATER Potential Current
12 MONTHS LATER Potential Current
mV
uA
mV
uA
mV
uA
mV
uA
1
-150
5
-300
70
-130
10
-130
2
2
-200
5
-350
90
-150
10
-200
3
Organic Vapor Phase Migratory Inhibitor
REBAR
FRESH CONCRETE
DEPTH
Potential Current
CORROSION ACTIVE Potential Current
60 DAYS LATER Potential Current
12 MONTHS LATER Potential Current
mV
uA
mV
uA
mV
uA
mV
uA
1
-150
5
-300
70
-70
15
-300
2
2
-200
5
-390
50
-80
15
-170
3
PAINT PLUS MIGRATORY CORROSION INHIBITOR PAINT TYPE 2 Part Epoxy Polyamide Primer, Formula 150,Type III Conformance:MIL-DTL-24441/20
MIGRATORY CORROSION INHIBITOR Type: Amine-carboxylate added to part A Concentration: 2.5weight percent of dry film solids
APPLICATION Spray applied on new and pre-corroded ASTM A1008 carbon steel panels
abraded with black beauty
PAINT PLUS MIGRATORY CORROSION INHIBITOR PERFORMANCE EVALUATION APPLICATION
2 To 3 Mil Film On Abraded White And Corroded Steel Panels EXPOSURE 500 Hours In Salt Fog Chamber Per ASTM B117 PERFORMANCE MEASUREMENTS Film Adhesion Per ASTM D3359 On Scale 0 To 5 Creep From X Score Per ASTM D1654 On Scale Of 0 To 10 (10 No Creep)
Degree Of Rust On Smooth Side Per ASTM D610 On Scale Of 0 To10
COMPARISON OF PERFORMANCE WITH AND WITHOUT MIGRATORY INHIBITOR ADDED TO PAINT APPLIED ON CORRODED STEEL PANELS VCI TYPE CONDITION ADHESION CREEP DEGREE OF RUST 2
Without VCI
4B
3
4
With VCI
5B
6
8
COMPARISON OF PERFORMANCE WITH AND WITHOUT MIGRATORY INHIBITOR ADDED TO PAINT APPLIED ON WHITE STEEL PANELS VCI TYPE
CONDITION Without VCI 1 With VCI Added * average of 4 panels
ADHESION CREEP 5B 5.25 4B 6.25
DEGREE RUST 3.0 8.75
BENEFITS OF PAINT PLUS MIGRATORY CORROSION INHIBITOR CAN BE APPLIED ON RUST COVERED STEEL WILL MIGRATE THROUGH RUST TO WHITE
METAL SURFACE AND TO HARD TO COAT RECESSED AREAS CAN PERFORM SPOT COATING MAINTENANCE WITHOUT NEED FOR SURFACE PREPARATION TO WHITE METAL USE AS PRIMER COAT FOR FINAL FINISH COAT
MIGRATORY CORROSION INHIBITORS A TOOL FOR PRESERVATION OF BRIDGES APPLY ON EXISTING REINFORCED CONCRETE
BRIDGE DECKS AND STRUCTURES EXPERIENCING REBAR CORROSION TO EXTEND LIFE. ADD TO CONCRETE MIX OR ON SURFACE OF NEW BRIDGES TO INHIBIT DAMAGE FROM FUTURE CORROSION CONDITIONS. APPLY PAINT WITH MIGRATORY CORROSION INHIBITORS ON BRIDGE STEEL STRUCTURES AND COMPONENTS.