Comparison of Surface Comparison of Surface Resistivity to Bulk Resistivity to Bulk

Diffusion Testing of Diffusion Testing of ConcreteConcrete

Christopher C. Ferraro Ph.D. Assistant In Engineering Department of Civil and

Coastal Engineering, University of Florida

Mario Paredes P.E. Mario Paredes P.E. State Corrosion EngineerState Corrosion Engineer

Florida Department Florida Department TransportationTransportation

Corrosion induced deterioration is the most common cause of bridge

degradation in Florida

Research SignificanceResearch Significance

FDOT Chloride Penetration FDOT Chloride Penetration Research ProgramResearch Program

Started In 2002, Consisted of 3 phases:Started In 2002, Consisted of 3 phases: 11stst Phase (2002-2003): Characterization of Phase (2002-2003): Characterization of

structural concrete placed in the field usingstructural concrete placed in the field using AASHTO T277/ASTM C1202 – Chloride Penetration Test AASHTO T277/ASTM C1202 – Chloride Penetration Test Surface Resistivity (Florida Method FM5-578) Surface Resistivity (Florida Method FM5-578)

22ndnd Phase(2003-2007): Find the best electrical Phase(2003-2007): Find the best electrical indicators of permeability correlated to indicators of permeability correlated to diffusiondiffusion

Bulk Diffusion (NT Build 443)Bulk Diffusion (NT Build 443) RMT (NT Build 492)RMT (NT Build 492) AASHTO T277/ASTM C1202 – Chloride Penetration Test AASHTO T277/ASTM C1202 – Chloride Penetration Test Surface Resistivity (Florida Method FM5-578)Surface Resistivity (Florida Method FM5-578)

3rd Phase (2007-2009): Surface Resistivity as a 3rd Phase (2007-2009): Surface Resistivity as a nondestructive test to evaluate field structuresnondestructive test to evaluate field structures

4

The Chloride Ion The Chloride Ion Penetration TestPenetration Test

Cut and Epoxy26th Curing Day

Desiccate27th Curing Day

Cell Formation3rd Day of Test28th Curing Day

Performing Test3rd Day of Test28th Curing Day

The Chloride Ion The Chloride Ion Penetration TestPenetration Test

6

Chloride Ion Penetration Test Chloride Ion Penetration Test AASHTO-T277/ASTM C1202AASHTO-T277/ASTM C1202

Stanish, K.D. et alNegatively charged ions move from the anode reservoir to the cathode reservoir.

7

Chloride Ion Penetration Test Chloride Ion Penetration Test LimitationsLimitations

TemperatureTemperature Ionic ContributionIonic Contribution Hydroxyl ion formationHydroxyl ion formation Conductive MaterialsConductive Materials Effort Required for Specimen PreparationEffort Required for Specimen Preparation Cost Cost

Diffusion TestBulk Diffusion (NT Build 443)

Cylinder is sliced at 364 days of exposure for Chloride analysis

Each slice is ¼ in thick

16.5 % NaCl

Bulk Diffusion Test Bulk Diffusion Test NordTest NTBuild 443 NordTest NTBuild 443

16.5 % NaCl Solution

Sealed on All Faces Except One

Concrete Cylinder (4 in diameter, 4 in length)

10

Electrical Indicators of Ion Electrical Indicators of Ion PenetrationPenetration

NT Build 443 - RMTFM5-522Impress Current

Stanish, K.D. et al

SurfaceSurface Resistivity FM 5-578

Surface Resistivity Testing

8"

Top

Bottom Probe Spacing a =1.5"

4"

Wenner Array Probe

Resistivity MeterKOhm - cm

a a a

Small AC signal

Broomfield, J. et al Applied Current

Measured Voltage

Surface Resistivity

Chloride Ion Penetration Test LimitationsChloride Ion Penetration Test Limitations

14

Advantages of the Surface Advantages of the Surface Resistivity TestResistivity Test

TemperatureTemperature Ionic ContributionIonic Contribution Hydroxyl ion formationHydroxyl ion formation Effort Required for Specimen PreparationEffort Required for Specimen Preparation Cost Cost

Conductive Materials – Still a problemConductive Materials – Still a problem

Chini, A. et al 529 Data Sets

Comparison of Resistivity and Chloride Ion Penetration

Coulomb Values

Surf

ace

Res

istiv

ity

(k

-cm

)

16

Precision of MethodsPrecision of Methods

Single-Operator Precision for penetration testingSingle Operator Coefficient of Variation:

• Surface Resistivity = 8.2%

• Chloride Penetration Test = 12.3%

y = 49.85x-0.7379

R2 = 0.7884 y = 42.781x-0.6125

R2 = 0.7383

1

10

100

0.1 1.0 10.0 100.0

Diffusion (10-12 m2/s)

Res

istiv

ity (K

Ohm

-cm

)

1 Year 3 Year

91 Day SR Correlation to 1 & 3 year BD

18

Research ProgramResearch Program cont.cont.

The third phase of researchThe third phase of research Surface resistivity as a NDT test to Surface resistivity as a NDT test to

evaluate field structuresevaluate field structures Surface Resistivity as a Performance

Test for Transport Properties Presuel-Moreno et.al (yesterday’s sesson)

19

Geometry EffectsGeometry Effects ρρreal ≠ real ≠ ρρmeasuremeasure

• Curvature of sample forces equi-potential lines into urvature of sample forces equi-potential lines into smaller smaller areas.areas.• The result is a modified resistivity reading.The result is a modified resistivity reading.

The real resitivity of concrete can be calculated byThe real resitivity of concrete can be calculated by

ρρrealreal == ρ ρmeasuremeasure/K/K

Where K is a correction factor that accounts for the Where K is a correction factor that accounts for the geometrical effects of the test (Morris, W. et al.)geometrical effects of the test (Morris, W. et al.)

20

Geometry EffectsGeometry EffectsMorris, W. et al

21

Geometry EffectsGeometry EffectsSurface Resistivity vs Distance

from Top of 6 x 12 Cylinder

5.0

5.5

6.0

6.5

7.0

7.5

0 1 2 3 4 5 6 7 8

Distance from Top (Inches)

Surf

ace

Res

istiv

ity (K

Ohm

s-cm

)

0 Min 15 Min 30 Min 45 Min 60 Min 75 Min 180 Min

Drying Time

22

Geometry EffectsGeometry EffectsSurface Resistivity vs Time

6 x 12

5.0

5.5

6.0

6.5

7.0

7.5

0 20 40 60 80 100 120 140 160 180

Minutes

Surf

ace

Res

istiv

ity (K

Ohm

s-cm

)

0" 1" 2" 3" 4" 5" 6" 7"

Distance From Top

23

4 3 2 1 -1 -2 -3 -40

30

60

180

5.0

5.5

6.0

6.5

7.0

7.5

Sur

face

Res

istiv

ity (K

Ohm

s-cm

)

Distance from Center (Inches)

Tim

e (M

inut

es)

Surface Resistiv ity vs Time and Distance

7.0-7.5

6.5-7.0

6.0-6.5

5.5-6.0

5.0-5.5

Geometry EffectsGeometry Effects

24

Geometry EffectsGeometry EffectsSurface Resistivity vs Curing Condition

Class VW/C=0.39 Fly Ash=20%

0

20

40

60

80

100

120

140

160

180

0 20 40 60 80 100 120 140 160 180 200

DAYS

SUR

FAC

E R

ESIS

TIVI

TY (K

ohm

s-cm

)

Moisture Room Lime Tank Outside

RCP DATA SR 28 Days 180 Days 28 Days 180 Days Coulomb Coulomb KOhm-cm KOhm-cmMoisture Room 5792 954 7.5 40.2Lime Tank 6715 1411 7.1 25.7Outside (Air cured) 4918 1182 20.7 155.2

25

References:References:“Florida Method of Test for Concrete Resistivity as an Electrical Indicator of Its Permeability”, (FM5-578) Florida Department of Transportation, 2004

“Standard Method of Test for Resistance of Concrete to Chloride Ion Penetration”, (T259-80), American Association of State Highway and Transportation Officials, Washington, D.C., U.S.A., 1980

“Standard Method of Test for Electrical Indication of Concrete’s Ability to Resist Chloride”, (T277-93), American Association of State Highway and Transportation Officials, Washington, D.C., U.S.A., 1983

“Standard Test Method for Electrical Indication of Chloride’s Ability to Resist Chloride” (ASTM C1202-94) 1994 Annual Book of ASTM Standards V 04.02, ASTM, Philadelphia, pg. 620-5

Berke, N. S., and Hicks, M.C., “Estimating the Life Cycle of Reinforced Concrete Decks and Marine Piles Using Laboratory Diffusion and Corrosion Data”, Corrosion Forms and Control for Infrastructure, ASTM STP 1137, V. Chaker, ed., American Society for Testing and Materials, Philadelphia, 1992

Broomfield, J., and Millard, S., “Measuring Concrete Resistivity to Assess Corrosion Rates”, Concrete Report from the Concrete Society/Institute of Corrosion Liaison Committee, pp. 37-39

Chini, A., Muszynski, L., Hicks, J., “Determination of Acceptance Permeability Characteristics of Performance-Related Specifications for Portland Cement Concrete”, Florida Department of Transportation, July 11, 2003

Hooton, R., Thomas, M., Stanish, K., “Prediction of Chloride Penetration in Concrete”, Federal Highway Administration, October 2001

Morris, W., Moreno, E.I. and Sagues, A. A., “Practical Evaluation of Resistivity of Concrete in Test Cylinders using a Wenner Array Probe”, Cement and Concrete Research, Vol. 26, No. 12, pp. 1779-1787, 1996

Powers, R., Sagues, A., Cerlanek, W., Kasper, C., Li, L., Liang, H., Poor, N., Baskaran, R., “Corrosion Inhibitors in Concrete Interim Report”, Federal Highway Administration, FHWA-RD-02-002, March 2002

Stanish, K., Hooton, R., Thomas, M., “Testing the Chloride Penetration Resistance of Concrete: A Literature Review”, FHWA Contract DTFH61-97-R-00022”Prediction of Chloride Penetration in Concrete”

Streicher, P.E. and Alexander, M.G., “A Chloride Conduction Test for Concrete”, Cement and Concrete Research, Vol. 25, No. 6, pp. 1284-1294, 1995