Data Collection and Performance Monitoring of an Instrumented ...

P3 2009 Pavement Performance Prediction Symposium: July 15-17, 2009, Laramie, Wyoming 

Data Collection and Performance Monitoring 

of an Instrumented 

Flexible Pavement Section on I-35 

Pranshoo Solanki 

Musharraf Zaman 

K. K. Muraleetharan 

University of Oklahoma 

July 16, 2009


Acknowledgement 

• ODOT 

– Bryan Cooper, Mike Brutsche, Bryan Hurst, Jeff 

Dean, Danny Gierhart, Lester Harragarra, Chris 

Clarke, Scott Cosby, Red Raley, Bruce Valley 

• NCAT 

– David Timm, Angela Priest, Brian Waller, Thomas 

McEwen, Jason Moore, 

• Langston University 

– Wilson Brewer 

• Haskell Lemon Construction Co. 

– Jay Lemon, Phillip Hawkins, Casey Hawkins


Outline 

• Objectives 

• Pavement Design & Field Instrumentation 

• Pre-Installation Efforts 

• Construction & Instrumentation 

• Field Data Collection & Processing 

• Pavement Material Characterization 

– Natural and stabilized subgrade soil, aggregate 

base, asphalt concrete 

• Performance Tests: Laboratory & Field 

– Rut, Fatigue cracking, Pavement layer modulus 

• Future Work


OBJECTIVES


Objectives 

• Develop transfer functions 

– Rut 

– Fatigue 

• Study secondary roadway using I-35 

– Thinner Section 

– Accelerated Conditions 

• Better understand M-E design 

– Actual vehicular traffic loading 

– Environmental factors


M-E 

Material 

Properties 

Analysis 

N 

f 

= 

k1( 

1 

Environment 

ε 

) 

Pavement Structure 

t 

k 

1 

2 

( ) 

E 

k 

Traffic 3 

σ ε 

Response 

Transfer Function 

Pavement Performance


PAVEMENT DESIGN & 

FIELD 

INSTRUMENTATION


Location of Site 

• I-35 South Bound, McClain County 

(Oklahoma) 

• 1000-ft. test section 

Instrumented Site 

WIM Site


Pavement Section 

2” S-4 HMA 

5” S-3 HMA 

8” Type A Aggregate Base 

8” Stabilized Subgrade (Fly Ash @ 12%) 

Natural Subgrade


Instrumentation Array 

Edge of Driving Lane 

Axle Sensors 

Stabilized 

Subgrade 

Stress 

4 ft 

1 ft 1 ft 

2 ft 

Outside Wheel Path 

2 ft 

Subgrade 

Stress 

2 ft 

2 ft 

Base 

Stress 

2 ft 

7 ft 

5 ft 

9 ft 

12 ft 

Center Line Stripes 

Moisture Probes 

Strain Gauge 

Earth Pressure 

Cell 

Temperature 

Probes


Instrumentation Layout 

Asphalt Concrete 

Aggregate 

Base 

Stabilized 

Subgrade 

Subgrade


Types of Data Collected 

• Dynamic Data 

– Strain; Stress (EPC); Wheel wander (Offset) 

• Environmental Data 

– Pavement temperature; Moisture under the 

pavement; Ambient temperature, Rainfall, 

Wind Speed, Humidity, Solar radiation 

• Traffic Data 

– Weight/axle, Speed 

• Performance Data 

– FWD testing; 

– Rut measurements; Crack mapping


Dynamic Data 

• Strains: CTL Asphalt Strain Gages 

• Butyl rubber outer core 

• Measure transverse and longitudinal strain 

• Total strain gages required: 12 

– 3 in two rows for transverse strain 

– 3 in two rows for longitudinal strain


Dynamic Data (Cont’d) 

• Stress: Geokon 3500 Earth Pressure Cell 

• 9.0-in. diameter steel plates filled with oil 

• Maximum bearing capacity of 36.3 psi 

• Total earth pressure cells: 3 

– Natural subgrade; Stabilized subgrade; Aggregate base


Dynamic Data (Cont’d) 

• Wheel wander: Dynax ® Axle Sensors 

• Z-pattern to measure transverse wheel placement 

• Total sensor: 3 

– 2 parallel sensors: 88.0-in. long 

– 1-diagonal sensor: 120.0-in. long


Environmental Data 

• Pavement temperature: Campbell Scientific, Inc. 

thermistors 

• Thermistor in epoxy-filled aluminum housing 

• Total thermistors: 5 

– 0.0-in.; 2.0-in.; 3.5-in.; 7.0-in. (asphalt concrete) 

– 10.0-in. (aggregate base)


Environmental Data (Cont’d) 

• Moisture under the pavement: ECH2O, EC-5 

• Measures dielectric constant of soil 

• Installed 3.0-in. below surface 

• Total sensors: 3 

– Natural subgrade; Stabilized subgrade; Aggregate base


Environmental Data (Cont’d) 

• Weather Station 

– Ambient temperature 

– Rainfall 

– Wind Speed 

– Humidity 

– Solar


Traffic Data 

• Vehicle Classification: WIM (Weigh-In-Motion) site


Performance Data 

• Pavement Layer Moduli: FWD using Dynatest 

Model # 8000 

• Plate diameter = 11.8-in.; Load = 6, 9, 12 and 15 

kips; Sensor spacing = 0, 8, 12, 24, 36, 48, 72 in. 

• Location: six identified stations


Performance Data (Cont’d) 

• Rut Measurements and Crack Mapping 

• Rut: Straight edge and rut gage; Face Dipstick ® 

• Crack: Grid pattern 

• Location: Six identified stations


PRE-INSTALLATION 

EFFORTS


Pre-Installation Efforts 

• Asphalt Strain Gauges 

• Calibration Information 

• Checked for functionality 

• Cable Ties were attached 

V ( Calib. 

Excitation Voltage) 

30mV 

Multiplier = 

× Calibration Factor × 

V ( DATAQ Excitation Voltage) 

5V


Pre-Installation Efforts (Cont’d) 

• Earth Pressure Cells 

• Calibrated at NCAT 

Pr essure = 7.2615*Voltage −0.2844 

• Checked for functionality


Pre-Installation Efforts (Cont’d) 

• Moisture Probes 

• Calibrated at OU for site specific material


CONSTRUCTION & 

INSTRUMENTATION


Excavation of Existing Weak Subgrade Soil and Backfilling with 

Imported Soil (Apr . 29 May 0 1, 2008 ) 

Grading and Compaction of Subgrade Soil ( May 0 2, 2008 ) 

Construction of Stabilized Subgrade Layer (SSG) ( May 0 5, 2008 ) 

Installation of EPC and MP on Subgrade Layer ( May 0 5, 2008 ) 

Heavy Rainfall (May 07, 2008) 

FWD on SSG (May 10, 2008) 

Installation of Earth Pressure Cell and Moisture Probe on Stabilized 

Subgrade Layer ( May 12 , 2008 ) 

Construction of Aggregate Base Layer (AGB) ( May 12 , 2008 ) 

FWD on AGB (May 13, 2008) 

Priming on Aggregate Base Layer ( May 13 , 2008 ) 

Installation of Earth Pressure Cell, Moisture Probe and Asphalt 

Gages on Aggregate Base Layer ( May 14 , 2008 ) 

Strain 

Paving with Asphalt Concrete (AC) ( May 14 – May 15 , 2008 ) 

Driving Nails (May 28, 2008) 

Installation of Temperature and Lateral Positioning Sensors; Cutting of 

Block and Cylindrical Asphalt Concrete Samples ( May 16 , 2008 ) 

FWD on AC (May 16 – May 20, 2008 2008) 

Removal of Concrete Traffic Barriers ( May 28 , 2008 ) 

Striping and Opening of Lane for Vehicular Traffic ( May 30 , 2008 )


Subgrade Compaction and Grading


Construction of Stabilized Subgrade


Installation of EPC on Subgrade 

Traffic Direction


Installation of MP on Subgrade 

Traffic Direction


FWD Test on Stabilized Subgrade


Installation of EPC and MP on SSG


Installation of EPC and MP on SSG


Construction of Aggregate Base


Installation of ASG


Paving Operation


Paving Operation


Installation of Temperature Sensor


Installation of LPS


Field Compacted Samples


Field Compacted Samples


Opening of Traffic


FIELD DATA COLLECTION 

& PROCESSING


Temperature 

Probes 

Moisture Content 

Strain 

Stress 

Air Temperature 

Offset


# of Axles 

Weight (Kips) 

ESAL


Data Collection - Procedure 

Site visited once a week 

Data collected for 20 

class 9 vehicles (five 

axles) 

Takes 10 to 20 min. 

depending on traffic.


Data Processing 

• Watch video footage. 

• Match & Combine Data coming from the 

DataQ System and the WIM station. 

• Construct a table with the Data recorded. 

• Use a software developed by NCAT to add 

strain measurements and other data 

parameters to the table.


Results – Wheel Wander 

• 05 Dec, 2008: Total 24 weekly trips for 

data collection 

• Weekly trip: 20 class 9 vehicles (5 axles)


Results – Long. VS. Trans. Strain 

• Each class 9 vehicle provides five 

maximum longitudinal and transverse 

strain peaks


Results – Strain VS. Temperature 

e 

α 

t 2 T 

1 

ε = α


PAVEMENT MATERIAL 

CHARACTERIZATION


Natural Subgrade Layer 

• Soil collected from site 

– Soil classification test (lean clay) 

• Proctor test (ASTM D 698) 

– OMC = 14.5%; MDD =110.4 pcf 

• Resilient Modulus (M r ) 

– Six specimens (OMC & OMC+2%) 

– M r (OMC) = 15-20 ksi; 

– M r (OMC+2%)= 11-16 ksi


Stabilized Subgrade Layer 

• Fly ash collected from site 

– 12% Class C fly ash (CFA) 

• Resilient Modulus (M r ) 

– Six specimens (OMC & OMC+2%) 

– Curing for 2, 8, 16, 23 and 30 days


Aggregate Base Layer 

• Bulk aggregates collected from site 

– Gradation 

– Washed, oven-dried and sieved 

• Resilient Modulus (M r ) at OMC 

– Three specimens 

– M r = 14 – 49 ksi


PERFORMANCE TESTS: 

LABORATORY & FIELD


Rut Test 

• APA Rut Test 

– S4 Mix 

– OHD L-43 

– Field compacted cylinders 

– Laboratory compacted cylinders 

• Parameters 

– Air voids (2±1%, 4±1%, 6±1%, 8±1%, 10±1%) 

– Temperature (40 o C, 50 o C, 64 o C)


Rut Test Results 

12 

Manual APA Rut Measurements (mm) 

10 

8 

6 

4 

T = 40 deg C 

T = 50 deg C 

T = 64 deg C 

T = 64 deg C (Field Compacted) 

y = 0.3382x + 3.8833 

R² = 0.659 

y = 0.4388x + 1.0509 

R² = 0.9092 

y = 0.331x + 0.5289 

R² = 0.5971 

2 

0 

0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 

Air Voids (%)


Field Rut Measurements (May 19, 2009) 

• Maximum rut value at sta. 235 

– 0.45 in from Dipstick; 0.30 in from rut gage


Fatigue Test 

• Four-point fatigue test 

– AASHTO T 321 

– Field compacted beams (SemMaterials, L.P.) 

– Laboratory compacted beams 

• Parameters 

– Air voids (2±1%, 4±1%, 6±1%, 8±1%, 10±1%) 

– Temperature (5 o C, 20 o C, 40 o C)


Fatigue Test Results 

• Four-point fatigue test 

– AASHTO T 321 

– Number of cycles to failure = 70,000 (T = 

5 o C); Air voids = 8.5% 

– Number of cycles to failure = 240,000 (T = 

20 o C); Air voids = 8.5%


Falling Weight Deflectometer (FWD) 

• Dynatest Model 8000 series 

– Performed on top of six stations 

– Top of sensors (strain gauge & pressure cell) 

• Aggregate Base/Stabilized Subgrade 

– Plate size: 17.9-in. 

– Load: 6, 8, 12 kips 

– Sensor spacing: 12, 24, 36, 48, 60, 72-in. 

• Asphalt concrete (different time/temperatures) 

– Plate size: 11.8-in. 

– Load: 6, 8, 12, 15 kips 

– Sensor spacing: 8, 12, 24, 36, 48, 72-in.


FWD Results: Asphalt Concrete 

β T 

E = β e 

2 

1 

4000 

3500 

HMA Stiffness, ksi 

3000 

2500 

2000 

1500 

1000 

y = 22179e -0.047x 

R² = 0.8405 

500 

0 

30 40 50 60 70 80 90 100 110 120 

Average Pavement Temperature, F 

Filtered Data 

Expon. (Filtered Data)


Pavement Instrumentation Response 

• FWD conducted on top of each strain gauge 

after construction 

– Structural analyses performed using KENPAVE (calculated) 

– Percent difference (1% - 24%) increases with loading level 

Strain Gauge 

Number 

Load (lbs.) 

Measured 

Micro Strain 

Calculated 

Percent 

Difference 

6,000 109.7 102.2 7 

6 (Transverse) 

9,000 138.3 153.3 11 

12,000 175.9 204.3 16 

15,000 212.7 255.3 20 

6,000 108.2 102.2 6 

8 (Transverse) 

9,000 128.4 153.3 19 

12,000 182.4 204.3 12 

15,000 216.7 255.3 18 

6,000 103.3 102.2 1 

10 

(Longitudinal) 

9,000 129.8 153.3 18 

12,000 182.9 204.3 12 

15,000 218.3 255.3 17 

11 

(Longitudinal) 

6,000 106.0 102.2 4 

9,000 127.1 153.3 21 

12,000 168.4 204.3 21 

15,000 206.2 255.3 24


Pavement Instrumentation Response 

• FWD conducted on top of each earth pressure 

cell after construction 

– Structural analyses performed using KENPAVE (calculated) 

– Pressure cell nearest to the loading surface shows the best 

agreement with the calculated values 

– Difference between measured and calculated values could be 

attributed to the major assumptions of elastic theory used by 

KENPAVE (e.g., all layers are assumed to be infinite, static load, 

etc.) 

Stress (psi) 

Pressure Cell 

Location 

Natural 

Subgrade 

Stabilized 

Subgrade 

Aggregate 

Base 

Load (lbs.) 

Measured 

Calculated 

Percent 

Difference 

6,000 1.1 2.6 131 

9,000 1.5 3.8 162 

12,000 2.2 5.1 133 

15,000 3.1 6.4 104 

6,000 3.7 4.9 34 

9,000 4.5 7.4 63 

12,000 6.4 9.8 54 

15,000 8.5 12.3 45 

6,000 9.1 9.5 4 

9,000 11.6 14.2 22 

12,000 17.3 18.9 9 

15,000 22.6 23.6 5


FUTURE WORK


Shift Factors 

• Attributes the difference between laboratory 

and field peformance 

– (e.g., field fatigue life > lab fatigue life) 

• Several reasons 

– Difference in state of stress, traffic wander, 

material difference between field and lab, HMA 

healing due to rest period 

Shift Factors


Fatigue Shift Factors 

• Stress state shift factor (SH s ) 

SH 

2 

Exε 

x 

2 

2 σ 

z 

+ Exε 

y 

+ 

1.46E 

• Material shift factor (SH m ) 

s 

SH 

W 

= 

W 

m 

uni 

tri 

= 

2 

( E ε 

• Traffic-wander shift factor (SH t ) 

SH 

t 

field 

x 

= N / N = g / 

∞ 

∫ 

−∞ 

x 

lab 

( d −b) 

( S ) f ( S ) = S 

x 

) 

c 

a 

ε ( x) dx / f ( x) ( x)dx 

f ( x) 

= ε 

ratio 

∞ 

∫ 

−∞ 

ratio 

= 

2 

1 x 

1 − 

2 

2 

σ 

e 

2πσ 

SH = SH × SH × SH 

s 

m 

t


Hourly middepth 

Temp 

E = β T 

1 

β 

2 

HMA 

Stiffness, E 

α 

t 

e 2 T 

1 

ε = α 

Measured 

Strain 

Calibration of 

Transfer Functions 

N 

f 

= 

k 

1 ( 

1 

) 

ε 

t 

k 

1 

2 

( ) 

E 

k 

3 

Cycles per Hour, n 

D 

= ∑ 

n 

N 

i 

fi 

Pavement 

Performance 

Solve regression constants such that 

D = 1 at time of failure


Outcome… 

• M-E performance model calibration or 

development 

• Laboratory data to field performance 

• Pavement response for dynamic effects on 

pavement deterioration from mechanistic 

viewpoint 

• Develop seasonal trends in pavement 

response 

• Correlate response to pavement damage

P3 2009 Pavement Performance Prediction Symposium: July 15-17, 2009, Laramie, Wyoming

Data Collection and Performance Monitoring of an Instrumented ...

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