s25 innovative testing ltc2013

7/29/2019 S25 Innovative Testing LTC2013

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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!

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