Transcript Comparison of Surface Resistivity to Bulk Diffusion

Comparison of Surface Resistivity to
Bulk Diffusion Testing of Concrete
Christopher C. Ferraro Ph.D.
Assistant In Engineering
Department of Civil and Coastal
Engineering, University of Florida
Mario Paredes P.E.
State Corrosion Engineer
Florida Department Transportation
Research Significance
Corrosion induced deterioration is the
most common cause of bridge
degradation in Florida
FDOT Chloride Penetration Research
Program
Started In 2002, Consisted of 3 phases:
1st Phase (2002-2003): Characterization of
structural concrete placed in the field using
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2nd Phase(2003-2007): Find the best electrical
indicators of permeability correlated to diffusion
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Bulk Diffusion (NT Build 443)
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RMT (NT Build 492)
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AASHTO T277/ASTM C1202 – Chloride Penetration Test
Surface Resistivity (Florida Method FM5-578)
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AASHTO T277/ASTM C1202 – Chloride Penetration Test
Surface Resistivity (Florida Method FM5-578)
3rd Phase (2007-2009): Surface Resistivity as a
nondestructive test to evaluate field structures
The Chloride Ion Penetration Test
Cut and Epoxy
26th Curing Day
Desiccate
27th Curing Day
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The Chloride Ion Penetration Test
Cell Formation
3rd Day of Test
28th Curing Day
Performing Test
3rd Day of Test
28th Curing Day
Chloride Ion Penetration Test
AASHTO-T277/ASTM C1202
Negatively charged ions move from the anode reservoir to the cathode reservoir.
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Stanish, K.D. et al
Chloride Ion Penetration Test Limitations
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Temperature
Ionic Contribution
Hydroxyl ion formation
Conductive Materials
Effort Required for Specimen Preparation
Cost
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Diffusion Test
Bulk Diffusion (NT Build 443)
Cylinder is sliced at
364 days of exposure for
Chloride analysis
16.5 % NaCl
Each slice is
¼ in thick
Bulk Diffusion Test
NordTest NTBuild 443
16.5 % NaCl Solution
Concrete Cylinder
(4 in diameter,
4 in length)
Sealed on All
Faces Except
One
Electrical Indicators of Ion Penetration
NT Build 443 - RMT
Stanish, K.D. et al
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FM5-522
Impress Current
Surface Resistivity FM 5-578
Surface Resistivity Testing
Small AC signal
Wenner
Array
Probe
a a a
Resistivity Meter
KOhm - cm
Bottom
Probe Spacing
a =1.5"
8"
4"
Top
Surface Resistivity
Broomfield, J. et al
Applied Current
Measured Voltage
Chloride Ion Penetration Test Limitations
Advantages of the Surface Resistivity Test
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Temperature
Ionic Contribution
Hydroxyl ion formation
Effort Required for Specimen Preparation
Cost
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Conductive Materials – Still a problem
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Comparison of Resistivity and Chloride Ion Penetration
529 Data Sets
Surface Resistivity (kW-cm)
Chini, A. et al
Coulomb Values
Precision of Methods
Single-Operator Precision for penetration testing
Single Operator Coefficient of Variation:
•
Surface Resistivity = 8.2%
•
Chloride Penetration Test = 12.3%
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91 Day SR Correlation to 1 & 3 year BD
100
Resistivity (KOhm-cm)
y = 49.85x-0.7379
R2 = 0.7884
y = 42.781x-0.6125
R2 = 0.7383
1 Year
3 Year
10
1
0.1
1.0
10.0
Diffusion (10
-12
2
m /s)
100.0
Research Program cont.
The third phase of research
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Surface resistivity as a NDT test to evaluate field
structures
Surface Resistivity as a Performance Test for
Transport Properties Presuel-Moreno et.al
(yesterday’s sesson)
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Geometry Effects
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ρreal ≠ ρmeasure
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Curvature of sample forces equi-potential lines into smaller
areas.
The result is a modified resistivity reading.
The real resitivity of concrete can be calculated by
ρreal = ρmeasure/K
Where K is a correction factor that accounts for the
geometrical effects of the test (Morris, W. et al.)
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Geometry Effects
Morris, W. et al
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Geometry Effects
Surface Resistivity vs Distance
from Top of 6 x 12 Cylinder
7.5
Surface Resistivity (KOhms-cm)
7.0
6.5
6.0
5.5
5.0
0
1
2
3
4
5
6
7
Distance from Top (Inches)
0 Min
15 Min
30 Min
45 Min
Drying Time 21
60 Min
75 Min
180 Min
8
Geometry Effects
Surface Resistivity vs Time
6 x 12
7.5
Surface Resistivity (KOhms-cm)
7.0
6.5
6.0
5.5
5.0
0
20
40
60
80
100
120
140
Minutes
0"
1"
2"
3"
4"
Distance From Top
22
5"
6"
7"
160
180
Geometry Effects
Surface Resistivity vs Time and Distance
7.5
6.5
7.0-7.5
6.5-7.0
6.0-6.5
6.0
5.5-6.0
5.0-5.5
5.5
5.0
4
30
3
2
Distan ce
1
-1
from Ce
nter (Inc
hes)
Mi
60
nu
te s
)
180
Ti m
e(
Surface Resistivity (KOhms-cm)
7.0
-2
23
-3
0
-4
Geometry Effects
Surface Resistivity vs Curing Condition
Class V
W/C=0.39 Fly Ash=20%
180
RCP DATA
SURFACE RESISTIVITY (Kohms-cm)
160
Moisture Room
Lime Tank
Outside (Air cured)
140
28 Days
Coulomb
5792
6715
4918
SR
180 Days
Coulomb
954
1411
1182
28 Days
KOhm-cm
7.5
7.1
20.7
180 Days
KOhm-cm
40.2
25.7
155.2
120
100
80
60
40
20
0
0
20
40
60
80
100
120
140
DAYS
Moisture Room
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Lime Tank
Outside
160
180
200
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
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