biogenic corrosion & cementitious repair materials
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Biogenic Corrosion & Cementitious Repair Materials. Joseph Talley ICRI Presentation. The Problem. Biogenic (H 2 S) Corrosion in Municipal Sewer Systems. Manholes Wet Wells Lift Stations WWTP Structures Pipe Lining. The Problem. Products Available. Cementitious Mortars - PowerPoint PPT PresentationTRANSCRIPT
Biogenic Corrosion & Cementitious Biogenic Corrosion & Cementitious Repair MaterialsRepair Materials
Joseph TalleyJoseph TalleyICRI PresentationICRI Presentation
The Problem...The Problem...
Biogenic (HBiogenic (H22S) Corrosion inS) Corrosion in
Municipal Sewer SystemsMunicipal Sewer Systems
• ManholesManholes• Wet WellsWet Wells• Lift StationsLift Stations• WWTP StructuresWWTP Structures• Pipe LiningPipe Lining
The Problem...The Problem...
Products AvailableProducts Available
• Cementitious MortarsCementitious Mortars
– Portland Cement Mortars – Portland Cement Mortars – Structural PropertiesStructural Properties• Portland Cement blended with natural aggregatesPortland Cement blended with natural aggregates• Portland Cement and pozzolons blended with natural aggregatesPortland Cement and pozzolons blended with natural aggregates• Bacteria Inhibiting admixtures are also availableBacteria Inhibiting admixtures are also available
– Calcium Aluminate Blended Mortars– Calcium Aluminate Blended Mortars– Mild Corrosion Resistance Mild Corrosion Resistance and Structural Propertiesand Structural Properties
• Calcium Aluminate cement blended with natural aggregatesCalcium Aluminate cement blended with natural aggregates
– 100% Calcium Aluminate Mortars– 100% Calcium Aluminate Mortars– Excellent Corrosion Excellent Corrosion Resistance and Structural PropertiesResistance and Structural Properties
• 100% Calcium Aluminate cement and Calcium Aluminate aggregate 100% Calcium Aluminate cement and Calcium Aluminate aggregate mortarsmortars
Products AvailableProducts Available
• Inert Coatings and LiningsInert Coatings and Linings– Epoxies and UrethanesEpoxies and Urethanes
• 100% solids generally recommended in underground 100% solids generally recommended in underground applicationsapplications
• Excellent chemical resistanceExcellent chemical resistance
• Installer dependentInstaller dependent
– Thermoplastic Sheet LinersThermoplastic Sheet Liners• Excellent chemical resistanceExcellent chemical resistance
• Installer dependent – seam welding is criticalInstaller dependent – seam welding is critical
• Labor intensive – used with mastic or cementitious Labor intensive – used with mastic or cementitious underlaymentunderlayment
– Cured-in-Place LinersCured-in-Place Liners• Excellent chemical resistance and structural propertiesExcellent chemical resistance and structural properties
• Installer and equipment dependentInstaller and equipment dependent
• Annular space must be properly addressedAnnular space must be properly addressed
Evaluation MethodsEvaluation Methods
Previous Evaluations of Concrete Corrosion Previous Evaluations of Concrete Corrosion Considered Only Acid Chemical AttackConsidered Only Acid Chemical Attack
Wet Acid Test Wet Acid Test MethodMethod
Does not consider Does not consider “bacterial aspect”“bacterial aspect”
Inability to Inability to reconcile lab results reconcile lab results with field resultswith field results
Corrosion TypesCorrosion Types
• ACID CHEMICAL - Diluted and Concentrated ACID CHEMICAL - Diluted and Concentrated Liquids (HLiquids (H22SOSO44))
• SULFATES - Soil or Water (SOSULFATES - Soil or Water (SO22 -- ions) ions)
• ALKALINE - (OHALKALINE - (OH-- ions) ions)
• BACTERIAL - The #1 Problem BACTERIAL - The #1 Problem Hydrogen Sulfide Atmosphere (HHydrogen Sulfide Atmosphere (H22S)S)
Biogenic CorrosionBiogenic Corrosion
Biogenic Corrosion KineticsBiogenic Corrosion Kinetics
SepticSewageEffluent
Stripping ofH2S in
Sulfate RichEnvironment
FoodSource
H2SOxidizing
intoElemental
Sulfur
Digestion byThiobacillus
Bacteria
Excretionof Sulfuric
Acid
AttackingAttackingSourceSource
Crown CorrosionCrown Corrosion
Research & Evolution of Evaluation MethodsResearch & Evolution of Evaluation Methods
The Hamburg University Test ChamberThe Hamburg University Test Chamber
Duplicates biogenic corrosionDuplicates biogenic corrosion
Municipal effluent and Municipal effluent and bacteria are usedbacteria are used
Temperature, humidity, Temperature, humidity, HH22S ppm are controlledS ppm are controlled
Corrosion calibrated Corrosion calibrated to harshest level (1 to 24 ratio to harshest level (1 to 24 ratio for the portland cement based for the portland cement based control mortar)control mortar)
* BIOGENIC AND CHEMICAL SULFURIC ACID CORROSION OF MORTARS – JOURNAL OF MATERIALS IN CIVIL ENGINEERING / NOVEMBER 1999
pH Evolution & Biogenic Corrosion (HpH Evolution & Biogenic Corrosion (H22S)S)
Portland CementPortland Cement Portland & PozzolonPortland & Pozzolon Calcium Aluminate BlendCalcium Aluminate Blend
100% Calcium100% CalciumAluminate MortarAluminate Mortar
Inert CoatingsInert Coatings
pH EvolutionpH Evolution
00 100100 200200 30030000
11
22
33
DaysDays
pH e
volu
tion
pH e
volu
tion
Understanding of Bacterial Activity:Understanding of Bacterial Activity:Bact
eria
l act
ivit
y
pH
T. Thiooxidans
I ncreasingacidity
T. Neapolitanus
T. tioparus
T. Intermedius
T. Novellus
9 8 7 6 5 4 3 2 1
There are different strains of Thiobacillus adapted to each pH range environment
Current Research activity into Microbiological Corrosion
• ASTM Committee C13 on Concrete Pipe
– C13.03 subcommittee formed in 2005 on “Determining the Effects of Biogenic Sulfuric Acid on Concrete Pipe and Structures”
– Organizing Industry funding to Michigan State University to complement pending NSF grant
– Goal is to identify specific thiobacilli with modern DNA sequencing
– This bacteria would then be used to innoculate material specimens to start the corrosion cycle and then maintain in a controlled chamber
Portland Cement Hydration KineticsPortland Cement Hydration Kinetics
•As Portland cement hydrates, calcium hydroxide As Portland cement hydrates, calcium hydroxide [Ca(OH)[Ca(OH)22] is inescapably liberated.] is inescapably liberated.
Ongoing Disruptive PhenomenaOngoing Disruptive Phenomena
•The “Ongoing Disruptive Phenomena” is the means of attack The “Ongoing Disruptive Phenomena” is the means of attack and failure of Portland cement based materials.and failure of Portland cement based materials.•The sulfuric acid produced by the bacteria attacks the calcium The sulfuric acid produced by the bacteria attacks the calcium hydroxide (lime) liberated during hydration:hydroxide (lime) liberated during hydration:
•Ca(OH)Ca(OH)22 + H + H
22SOSO44 CaSO CaSO
44 + 2H + 2H22OO
• Lime + Sulfuric AcidLime + Sulfuric Acid Gypsum + Water Gypsum + Water
Delamination of Inert Coatings Delamination of Inert Coatings
Protective – Reactive BarrierProtective – Reactive Barrier
• Calcium Aluminate Calcium Aluminate cement liberates cement liberates “gibbsite” (AH“gibbsite” (AH33) )
upon hydration.upon hydration.• Alumina gel inhibits Alumina gel inhibits
the bacterial activity the bacterial activity of the Thiooxidans of the Thiooxidans strain.strain.
AH3
• Alumina gel also neutralizes the acid produced Alumina gel also neutralizes the acid produced by the consumption of hydrogen ions:by the consumption of hydrogen ions:
–{AH{AH33 = Al = Al
22(OH)(OH)66} + 6H} + 6H++ 2Al 2Al3+3+ + 6H + 6H
2200
How CA Mortars WorkHow CA Mortars Work
{AH{AH33 = Al = Al
22(OH)(OH)66} + 6H} + 6H++ 2Al 2Al3+3+ + 6H + 6H
2200
•H2SO4 in solution becomes:
H+ + SO42- + HSO4
2- + H20 (hydrogen, sulfate, bisulfate ions & water)
•CA cement mixed with water hydrates to become:
C3AH6 + C2AH8 + AH3
•AH3 is cement notation (shorthand) for Al2(OH)6
•pH = -log[H+] , or the negative log of the molecular concentration of hydrogen ions in solution
•AH3 consumes H+ ions yielding:
2Al3+ + 6H20 (or Alumina ions and water)
•Consumption of H+ ions from solution reduces the H+ molecular concentration, therefore the pH is locally increased.
How 100% CA Mortars WorkHow 100% CA Mortars Work
•The CA aggregates are the key…
•As AH3 is consumed, an abundance of CA in unreacted cement and CA aggregates continue to hydrate in a humid sewerage environment, continuously forming more AH3.
{AH{AH33 = Al = Al
22(OH)(OH)66} + 6H} + 6H++ 2Al 2Al3+3+ + 6H + 6H
2200
•This is how a 100% Calcium Aluminate mortar can continue to locally raise the pH in this environment, taking us back to the bacterial strain graph…
Anhydrous (unreacted) CA grains
100% Calcium Aluminate Materials Inhibit Bacterial Activity:100% Calcium Aluminate Materials Inhibit Bacterial Activity:
• 100% CA mortars keep 100% CA mortars keep the system in a state of the system in a state of minimal bacterial activity minimal bacterial activity (between pH 3.0 and pH (between pH 3.0 and pH 4.0).4.0).
• The AHThe AH33 that is that is
continually released continually released from the aggregate from the aggregate system can be enough system can be enough to neutralize the to neutralize the additional Hadditional H++ ions ions produced by the produced by the bacteria.bacteria.
Bact
eria
l act
ivit
y
pH
T. Thiooxidans
I ncreasingacidity
T. Neapolitanus
T. tioparus
T. Intermedius
T. Novellus
9 8 7 6 5 4 3 2 1
Total Calcium Aluminate BarrierTotal Calcium Aluminate Barrier
• Combines the Protective-Reactive Barrier Combines the Protective-Reactive Barrier effects of both calcium aluminate cement effects of both calcium aluminate cement and manufactured calcium aluminate and manufactured calcium aluminate aggregates.aggregates.
• Calcium aluminate aggregates are Calcium aluminate aggregates are hydraulic and reactive.hydraulic and reactive.
•Both cement and aggregates have Both cement and aggregates have the same chemistry and the same chemistry and mineralogy. mineralogy. •This creates unmatched This creates unmatched neutralization capacity and neutralization capacity and produces both a physical and produces both a physical and chemical bond upon hydration.chemical bond upon hydration.
23
City of Ormond Beach, Florida: ReferenceCity of Ormond Beach, Florida: Reference
• 1”- 4” deterioration of Portland 1”- 4” deterioration of Portland
cement concrete in 5 yearscement concrete in 5 years
• Exposure of reinforcing steelExposure of reinforcing steel
• HH22S readings > 30 ppmS readings > 30 ppm
After 3 years in service the After 3 years in service the external attack on the discharge external attack on the discharge line, installed 1 year later than the line, installed 1 year later than the lining, clearly demonstrates the lining, clearly demonstrates the corrosive nature of this corrosive nature of this environment.environment.
After 9 years the state of lining After 9 years the state of lining remains excellent. Trowel remains excellent. Trowel marks are still present in the marks are still present in the corners…corners…
InstallationInstallation
• Cementitious Materials are relatively easy to Cementitious Materials are relatively easy to install…install…– Cementitious Mortars are designed for “wet” Cementitious Mortars are designed for “wet”
installations installations
• Contractor Qualifications are very importantContractor Qualifications are very important– Insist upon some type of manufacturer designation…Insist upon some type of manufacturer designation…
• CertificationCertification
• ApprovedApproved
• QualifiedQualified
– Similar work requirements…Similar work requirements…
• The Installer can be the most important factor for The Installer can be the most important factor for success with any rehabilitation material.success with any rehabilitation material.
Old manholes can be Old manholes can be very irregularly shaped very irregularly shaped and even have brick and even have brick missingmissing
Materials Materials are easily are easily mixed by mixed by just adding just adding waterwater
Manhole Rehab ProcessManhole Rehab Process
Spray-applied mortars are easily Spray-applied mortars are easily applied into the large voidsapplied into the large voids
Once applied, mortars can Once applied, mortars can quickly be finished to provide a quickly be finished to provide a
smooth liningsmooth lining
A masonry A masonry brush can be brush can be used for used for finishing to finishing to provide a provide a different lookdifferent look
Before & After RehabilitationBefore & After Rehabilitation
Before…Before…
……AfterAfter
Total Protective – Reactive Barrier ProcessTotal Protective – Reactive Barrier Process
Ongoing Disruptive Phenomena is
apparent with existing portland cement based materials The clean, prepared,
and reinforced structure receives a
100% Calcium Aluminate mortar
installation
The finished product exhibits the Protective – Reactive Barrier effect of
a 100% Calcium Aluminate structural lining
Existing Wet Well After Rehabilitation
Typical Wet Well RehabTypical Wet Well Rehab
Existing channel box in deteriorated condition Sluice gate installed and structure coated
Box Structure RehabBox Structure Rehab
Existing Wet Well Rehabilitated Wet Well
Typical Wet Well RehabTypical Wet Well Rehab
Existing Brick Manhole with Tidal Infiltration After Cementitious Rehabilitation
Manhole RehabilitationManhole Rehabilitation
Deteriorated Precast Manhole with Bench & Invert Problems Rehabilitated Entirely with Cementitious Mortar
Manhole RehabilitationManhole Rehabilitation
Precast Manhole with Failure of Existing Coating Existing Coating Removed and Mortar Installed
Manhole RehabilitationManhole Rehabilitation
QuestionsQuestions
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AnswersAnswers