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