s25 innovative testing ltc2013
TRANSCRIPT
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Innovative Concrete Testing
2013 Louisiana Transportation Conference
Tyson D. Rupnow, Ph.D., P.E.
Patrick Icenogle, P.E.
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Outline
Surface Resistivity
What is it?
Comparative Testing
Cost Benefit
Precision Statement
Ruggedness Study
MIT-Scan-T2What is it?
Proposed Research
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Background
ASTM C 1202
Quick
2 days of testing
Mostly samplepreparation
Expensive
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Background
Wenner Probe
Much quicker
Less expensive
Shorted curing time
Portable!
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Surface Resistivity Meter
Peg spacing = 1.5 inch
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Sample Markings
Average of eight total readings
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Sample Testing
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Test Factorial
Measure surface resistivity and RCP on varying
ages of samples
Ages of 14, 28, and 56 days
Sample size = 4 in. x 8 in. cylinders
Mixture ID
w/cm
0.35 0.50 0.65
100TI X X X
80TI-20C X X X
50TI-50G120S X X X
90TI-10SF X X X
95TI-5SF X X X
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AASHTO: RCP to SR
Chloride Ion
Permeability
High
ModerateLow
Very Low
Negligible
Table 2 Surface Resistivity - Permeability
Surface Resistivity Test
k-cm
< 12
> 254
12 - 2121 - 37
37 - 254
Chloride Ion Penetrability
High
ModerateLow
Very Low
Negligible
Table 1 Chloride Ion Penetrability Based on Charge Passed
Charge Passed (coulombs)
>4,000
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Results Overall Relationship
y = 29647x-0.944
R = 0.8922
0
1000
2000
3000
4000
5000
6000
7000
8000
0 50 100 150 200 250 300 350
AverageRapidChloridePermeability
(Coulombs)
Average Surface Resistivity (k-cm)
LTRC Data
AASHTO Correlation
Power (LTRC Data)
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Results 28 Day SR vs. 56 Day RCP
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Preliminary Cost Benefit
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Preliminary Cost Benefit
Total cost of the project: $102,878
Estimated 1 year savings: $1.6 million
Ratio of about 15
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Implementation
Test at 28-days of age, can use compression
samples
Accept on 28-days measurements of 27 k-cm
Purchased 11 SR meters, one for each state lab
State-wide training
Developed TR 233 procedure
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Caminada Bay Bridge
43 lots
7 hour trip for RCP sample delivery to LTRC
2.5 hour trip for SR sample delivery to District lab
One trip a week for three months
Save on technician drive, mileage, samplepreparation and testing time
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Implementation
50 bridges under construction per year by DOTD
Conservative savings of $20,000 per year perproject
DOTD saves an estimated $1,000,000 per year inoperational costs
Contractor QC savings are expected to be equal to
or greater than DOTD savings
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Surface Resistivity Precision
ASTM C802: Standard Practice for Conducting an
Interlaboratory Test Program to Determine thePrecision of Test Methods for Construction
Materials
ASTM C670: Standard Test Methods for Preparing
Precision and Bias Statements for Test Methodsfor Construction Materials
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Sample Set Averages
0
50
100
150
200
250
300
A B C D E F G H
Average
SurfaceResistiv
ity(k-cm)
Material
1
2
3
4
5
6
7
8
9
10
11
12
1314
15
16
17
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Lab Average
0
50
100
150
200
250
300
A E F H B C D G
AverageSurfaceResistivity(k-cm)
Material
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Estimates of Precision
R = 0.8309
R = 0.9585
0
2
4
6
8
10
12
0 100 200 300
StandardDevtion(k-cm)
Material Average (k-cm)
Within between Linear (Within) Linear (between)
0
1
2
3
4
5
6
7
0 100 200 300
Coeffie
cientofVariation(%)
Material Average (k-cm)
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Results
Single operator one-sigma limit in percent (1s%) is
average within-laboratory COV.
1s% = 2.2% Multilaboratory one-sigma limit in percent (1s%) is
average between-laboratory COV.
1s% = 3.9%
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Surface Resistivity Ruggedness
ASTM E1169: Standard Practice for Conducting
Ruggedness Tests
Planned experiment to determine factors or test
conditions and the level of influence of those factorsor conditions
Each factor is assigned two levels
Generally done on uniform material, however, some
factors for this study were mixture specific
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Ruggedness Factors
Factor Variable Discussion Level 1 (-) Level 2 (+)
A Aggregate Type Type of coarse aggregate Gravel Limestone
B Aggregate Size Size of coarse aggregate #57 #67
C Calcium Nitrite Presence of Calcium Nitrite in mixture Yes No
D
Lime Water Curing Curing in lime water tank Yes No
E Segregated Cylinder Segregation of aggregate in cylinder by vibration Yes No
F Air Entraining Presence of air entraining (0.50 oz/cwt) Yes No
G Temperature Conditioning temperature (water controlled) 76F 73F
H Surface Moisture Time of drying after saturated surface dry(temperature is air controlled for the 15 min)
SSD + 15minutes
SSD + 0minutes
I Age Age at measurement 14/56 day 28 day
J Meter OffsetOff set pegs from center of longitudinal side,placement at 1.25 inch from center
1.25" 0"
K Collection PatternCollecting 8 measurements in one revolution instead
of standard 4 in two revolutions8x1 4x2
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14/28 Results
0
0.5
1
1.5
2
2.5
0 0.5 1 1.5 2 2.5 3 3.5
HalfNorm
al
Effect
Aggregate Type
Age
Surface Moisture, interactions
Temperature, interactionsMeter Offset
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28/56 Results
0
0.5
1
1.5
2
2.5
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5
HalfNorm
al
Effect
Aggregate Type
Age
Surface Moisture, interactions
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Results
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
18.0
SurfaceResistivity(k-cm)
14 days 28 days 56 days
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Results
0.0
1000.0
2000.0
3000.0
4000.0
5000.0
6000.0
7000.0
8000.0
9000.0
0.0 50.0 100.0 150.0 200.0 250.0 300.0
RCP(Coulom
bs)
Surface Resistivity (k-cm)
Extra Factorial
LTRC Curve FitAASHTO Curve Fit
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Conclusions
Ruggedness study showed age and aggregate
type as significant factors for surface resistivity
Comparing individual factors against a control
suggests age, calcium nitrite, aggregate size, andaggregate type as significant factors for surfaceresistivity
Similar rapid chloride penetration results suggestthese factors influence permeability in general orwill influence both tests
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Non-Destructive Thickness
MIT SCAN-T2
2 mm
Quick measurements
Stores 16,000 points
Non-destructive
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Proposed Research
Evaluate MIT-SCAN-T2 as an alternative method
of determining pavement thickness in PCC andHMA pavements.
Pair with cylinder testing, maturity, or other non-destructive means of measuring pavementstrength for quality control/assurance.
Feasibility of MIT-SCAN-T2 to locate dowel barsand check alignment.
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MIT-SCAN-T2 Procedure
Place reflector on base layer Galvanized sheet metal
3 to 12 diameter plate
0.03 thickness
Pave right over reflector
Note general location
MIT-SCAN-T2
Eddy currents
Pinpoints reflector
Measures thickness
Must be used away from
other metal objects
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MIT-SCAN-T2
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Benefits
Reduction in cores.
Less damage to pavement.
Increased sampling frequency.
Less travel time and sample management.
Testing PCC pavement at earlier ages.
Calibration for GPR.
Possible QC/QA for dowel/tie bar locations andorientation.
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Research by Others
MIT-SCAN-T2 based on magnetic imaging
tomography.
Quick, easy to use, non-destructive.
5 minutes per measurement.
Can measure up to 20 inches in depth.
Can be run as soon as pavement can be
walked on.Accuracy is 0.1 inch for 12 inch thickness.
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Research by Others
Yu showed the device correlated extremely well
with step-frequency GPR.
CalTrans recommended for ease of use and no
calibration. Wisconsin DOT stated more effective and efficient
than coring.
Iowa DOT and MnDOT have included method inproject proposals.
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MIT SCAN-2
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Thank You!