1

Pavement Instrumentation

Imad L. Al-QadiFounder Professor of Engineering

Pavement Optimum Investment

RELIABILITY(pavement condition)

PRES

ENT

WO

RTH

OPTIMUM

100 %50 %

TOTAL COST

Future Investment Maint., Rehab., User, etc.

INITIAL COST

FAILURE CRITERIA IN PAVEMENTS

RUTTINGFATIGUELOW TEMPERATURE CRACKINGCONTAMINATIONDRAINAGE/ MOISTURE

2

RUTTING IN SUBGRADE OR BASE

originalprofile

weak subgrade or underlying layer

asphalt layer

subgradedeformation

RUTTING IN HMA

weak asphalt layer

shear plane

originalprofile

FATIGUE CRACKING

3

REFLECTION CRACKING

LOW TEMPERATURE CRACKING

Loaded Flexible Pavement

Aggregate Base Deflection

Free Water Wedge

Hydrostatic Pressure

Subgrade Deflection

Direction of Travel

BaseBase

Subgrade

HMA

4

Moisture Damage

Subgrade Subgrade

Soil Migration

Aggregate Penetration

PCC/ HMABase

Subgrade

5

Benefits of Instrumentation• Measurement of response• Prediction of performance/ failure• Life estimation• Pavement configuration comparisons• Modification of designs • Construction/ maintenance evaluation

HVS FL - 2001

ATLAS @ UIUC - 2002

MnRoad - 1993

WesTrack - 1995Carson City, Nevada

NCAT Track 2000

6

• Adaptable Facility for Transportation Research and Evaluation

• 2.5km Long: 12 Flexible Pavement Sections and One CRCP

• Instrumentation during Construction• Rain and Snow Towers

Virginia Smart Road

Pavement Instrumentation

• Selection• Calibration• Installation• Protection• Data Collection• Data Analysis

7

Instrument Selection

Subgrade

21B Aggregate Subbase21A Stabilized Subbase

Open Graded Drainage LayerSM 9.5-A (in 3 Sections)

BM 25.0W. Surface

Pressure Cell (Two Sizes)Aggregate Strain Gage

Vibrating Wire Strain Gage

H-Type Strain Gage (Asphalt)

Time Domain Reflectomer (Two Types)Thermocouple Resistivity Probe

Underground Bunker Houses Data Acquisition System

Instrumentation

Pressure Cell

Aggregate Strain GageVibrating Wire Strain

Gage

H-Type Strain Gage

8

Thermocouple

TDR (CS610) TDR (CS615)

Resistivity Probe

LVDT

Piezometer

Instrument Types

KyowaLiquid Level

Multi-Depth Deflectometer

9

Static Strain Gauge

Thermocouple

Dynamic Strain Gauge

Steel Strain Gauge

Instrumentation Planning

Smart Road Pavement Design

A B C D E F G H I J K LOGFC (19mm)SM-9.5D (19mm)

SM-9.5A (50mm)

SM-9.5A (50mm)

SM-9.5A (50mm)

BM-25.0 (225mm)

21B (75mm)

21B (75mm)

21B (75mm)

21A Cement

Stabilized (150mm)

Cement OGDL

(75mm)

21A Cement

Stabilized (150mm)

21A Cement

Stabilized (150mm)

OGDL (75mm)

OGDL (75mm)

21B (150mm)

21A Cement

Stabilized (150mm)

21B (175mm)

Cement OGDL

(75mm)

OGDL (75mm)

OGDL (75mm)

OGDL (75mm)

OGDL (75mm)

21B (175mm)

21B (175mm)

21B (175mm)

SM-12.5D (38mm)

SM-9.5D (38mm)

SM-9.5E (38mm)

SM-9.5A (38mm)

SM-9.5D (38mm)

SM-9.5D (38mm)

SM-9.5D (38mm)

SM-9.5D (38mm)

BM-25.0 (100mm)

SM-9.5A* (38mm)

SM-9.5D (38mm)

SMA-12.5 (38mm)

BM-25.0 (150mm)

BM-25.0 (100mm)

BM-25.0 (225mm)

21B (150mm)

BM-25.0 (100mm)BM-25.0

(150mm)BM-25.0 (150mm)

BM-25.0 (150mm)

BM-25.0 (150mm) BM-25.0

(225mm)

21A Cement

Stabilized (150mm)

21A Cement

Stabilized (150mm)

BM-25.0 (150mm)

21B (75mm)

21A Cement Stabilized (150mm)

21B (150mm)

21A Cement

Stabilized (150mm)

21A Cement

Stabilized (150mm)

21A Cement

Stabilized (150mm)

21B (75mm)

21A Cement

Stabilized (150mm)

CRCP

Concrete (250mm)

Cement OGDL

(75mm)

OGDL (75mm)

21B (150mm)

OGDL (75mm)

Geocomposite Membrane

Reinforcing Mesh

Woven Geotextile

Copper Plate

10

Smart Road Infrastructure

8

DaqBook 200

DBK cards

WaveBook 512

WBK10

WBK16

11

Data Logger & Multiplexers

Weather Station

Campbell Scientific

INSTRUMENT LOCATION AND DRIVING PATHS

12

Instrument Location

Preparation for Field Instrumentation

Instrument Preparation

13

Digging Trenches

Digging Trenches

14

Thermocouples and TDRs

Instrument Modification and Calibration

LVDT

15

LVDT Construction

TDR Calibration

TDR Calibration

16

Pressure Cell

Benddedrod

Instrument Installation

Pressure Cell Installation

17

PLACING HMA OVER INSTRUMENTS

INSTRUMENT INSTALLATION

COMPACTING ASPHALT OVER INSTRUMENTS

18

SPECIAL INSTRUMENTATION

Section K Section J

Section I Section L

Environment Instrumentation

LVDT Installation

19

Instrument Protection

Pressure Cells

Pressure Cells

20

Pressure Cells

Wrong

Instrument Protection

HMA Strain Gauges

21

Strain Gauge

Wiring

Wire Protection

22

WIRE TRENCHES

Laying Out Wires

WIRE SPLICING

23

Paving Process

Instrument In-situ Response

FWD Testing

24

FWD

FWD Testing Procedures (2)

Weight

Loading plate

Def

lect

ion

Distance

Typical deflection basins

B. B. Guzina and R. H. Osburn (2002)

A-B: LiftB-C: Drop

Geophones

-50

0

50

100

150

200

0 0.5 1 1.5 2Pulse Duration (secs)

Stre

ss R

espo

nse

(kPa

) 0

10

20

30

40

50

60

70

80

-1.5 -1 -0.5 0 0.5 1 1.5 2DISTANCE (ft)

Pres

sure

(psi

)

5000 lbs7000 lbs9000 lbs11000 lbs 13000 lbs

Instrument Response under

FWD Loading

25

FWD on Low Modulus Material

0300600900

120015001800

0 0.2 0.4 0.6 0.8 1Time (sec)

Stra

in ( μ

m/m

)

0300600900

120015001800

0 0.2 0.4 0.6 0.8 1Time (sec)

Stra

in ( μ

m/m

)

Vibrations: 40 Hz (2400 VPM)

Horizontal Transverse Strain under HMA

No Vibrations

-2500

-500

1500

3500

5500

7500

0 0.2 0.4 0.6 0.8 1Time (sec)

Stra

in ( μ

m/m

)

-2500

-500

1500

3500

5500

7500

0 0.2 0.4 0.6 0.8 1Time (sec)

Stra

in ( μ

m/m

)

Longitudinal Strain under HMA

Vibrations: 40 Hz (2400 VPM)

No Vibrations

26

050

100150200250300

0 0.2 0.4 0.6 0.8 1Time (sec)

Ver

tical

Str

ess (

kPa)

0100200300400500600700

0 0.2 0.4 0.6 0.8 1Time (sec)

Ver

tical

Str

ess (

kPa)

Vertical Compressive Stress

138mm

263mm

Data Management

Data Filtering

27

Data Collection and Management

• Several Visual C++ Software– SmartAcq: Configure Instruments and Acquire

Data – SmartOrganizer: Create Files per Section, Data

Type, and Date from Raw Files – SmartWave: Display and Analyze Dynamic Data

• Databases: Access with C++ Visual Interface– Temperature and Moisture – Stresses and Strains

Dynamic Data(Truck Loading)Dynamic Data

(Truck Loading)

Static Data(Environmental)

Static Data(Environmental)

Temperature(15 minutes)

Temperature(15 minutes)

Moisture(1 hour)

Moisture(1 hour)

Frost depth(6 hours)

Frost depth(6 hours)

Stress(2-second wave)

Stress(2-second wave)

Strain(2-second wave)

Strain(2-second wave)

TYPES OF DATA

Instrument Triggering and Data Saving

28

Data Management

Data Collection and Management• Static Data: One File Per Bunker Created

Every Day at Midnight (Tab-Delimited Text File)– Date, Section #, Type

• Dynamic Waves: One File Per Bunker with All Triggered Instruments Created Only during Truck Testing (Binary File) – Date, Load, Speed, Pressure, Section #

TDR and Vibrating Wire Configuration Window

29

Thermocouple and Frost Probe Configuration Window

Pressure Cells & Strain Gauges

DATA MANAGEMENT

30

Sample Pressure Cell Data

TYPICAL COLLECTED DATA (STRAIN)

DATA ANALYSIS

D05-24-2000L1S5P105ScB

31

DATA ANALYSIS

DATA ANALYSIS

DOWNLOAD DATA

32

Pavement Response

• 3 Load Levels (L1, L2, L3)

• 3 Tire Inflation Pressures (80, 95, 105 psi) (550, 655, 725 kPa)

• 4 Speeds (5, 15, 25, 45 mph) (8, 25, 40, 72 km/h)

Truck Loading

33

Time Domain Reflectometry

0

5

10

15

20

3/3/00 3/17/00 3/31/00 4/14/00 4/28/00 5/12/00 5/26/00

Date

Moi

stur

e C

onte

nt (%

)

0

5

10

15

20

25

30

35

40

45

50

Prec

ipita

tion

(mm

)

Precipitation

Moisture Content

0

5

10

15

20

3/14/00 3/28/00 4/11/00 4/25/00 5/9/00 5/23/00

Date

Moi

stur

e C

onte

nt (%

)

0

5

10

15

20

25

30

35

40

45

50

Pre

cipi

tatio

n (m

m)

Precipitation

Moisture Content

6

8

10

12

14

16

18

20

3/30/00 4/9/00 4/19/00 4/29/00 5/9/00 5/19/00 5/29/00 6/8/00date

volu

met

ric m

oist

ure

cont

ent (

%)

0

5

10

15

20

25

30

35

40

45

50

prec

ipita

tion

(mm

)

BM6-1MBM6-2Mprecipitation

6

8

10

12

14

16

18

20

3/30/00 4/9/00 4/19/00 4/29/00 5/9/00 5/19/00 5/29/00 6/8/00date

volu

met

ric m

oist

ure

cont

ent (

%)

0

5

10

15

20

25

30

35

40

45

50

prec

ipita

iton

(mm

)

EM6-1MEM6-2Mprecipitation

6

8

10

12

14

16

18

20

3/30/00 4/9/00 4/19/00 4/29/00 5/9/00 5/19/00 5/29/00 6/8/00date

volu

met

ric m

oist

ure

cont

ent (

%)

0

5

10

15

20

25

30

35

40

45

50

prec

ipita

tion

(mm

)

KM6-1MKM6-2Mprecipitation

05

101520253035404550

6/1 6/2 6/3 6/4 6/5 6/6 6/7 6/8

Date

Under WS

AmbientUnder 21B

TEMPERATURE DATA

34

TEMPERATURE EFFECT

0300600900

1200

10 12 14 16 18 20 22 24 26 28 30Temperature (°C)

5/24/009:00 AM10/19/008:50 AM

020406080

100120

-0.4 -0.2 0 0.2 0.4Time (s)

5/24/009:00 AM10/19/008:50 AM

8 km/h, 190mm

0

0.25

0.5

0.75

1

-0.4 -0.2 0 0.2 0.4Time (sec)

Nor

. Ver

t. C

omp.

St

ress

40mm 190mm 267mm419mm 597mm

0

0.25

0.5

0.75

1

-0.1 -0.05 0 0.05 0.1Time (sec)

Nor

m. V

ert.

Com

p.

Stre

ss

40mm 190mm 267mm419mm 597mm

72km/h

8km/h

)dt*

2(siny(t) 2 π+π

=

00.20.40.60.8

1

-0.1 -0.05 0 0.05 0.1

MeasuredHaversine

00.20.40.60.8

1

-0.01 -0.005 0 0.005 0.01

MeasuredHaversine

8km/h, 40mm, d=0.15s

72km/h, 40mm, d=0.02s

35

0.01

0.1

1

10

0 20 40 60 80Speed (km/h)

Hav

ersi

ne T

ime

(sec

)

597mm 419mm 267mm190mm 40mm

Haversine Duration vs. Depth and Speed

y = 45.852e0.0399x

R2 = 0.88

0

50

100

150

200

250

300

0 5 10 15 20 25 30 35 40 45Temperature (°C)

Vert

ical

Str

ess

(kPa

)

724kPa655kPa552kPaTrendline (all)

Effect of Tire Inflation Pressure on Measured Vertical Compressive Stress under HMA

EFFECT OF LOAD ON MEASURED VERTICAL STRESS UNDER HMA

y = 1.97e0.054x

R2 = 0.92

y = 2.55e0.0602x

R2 = 0.95

y = 5.26e0.0422x

R2 = 0.95

020406080

100120140160180

0 5 10 15 20 25 30 35Temperature (°C)

41.5kN30.1kN19.8kN

36

σ = 28.3e0.0565T

R2 = 0.920

50

100

150

200

0 10 20 30 40Temperature (C)

Ver

tical

Str

ess (

kPa) 8km/h 24km/h

40km/h 72km/h

Vertical Stress vs. Speed

0

50

100

150

200

10 15 20 25 30 35 40Temperature (°C)

Stra

in ( μ

m/m

)

8km/h 24km/h40km/h 72km/h

Transverse Strain vs. Speed

EFFECT OF TIRE INFLATION PRESSURE ON MEASURED HORIZONTAL TRANSVERSE STRAIN

UNDER HMA

8km/h

μstrain = 8.48e0.086T

R2 = 0.930

20406080

100120140160180

10 15 20 25 30 35 40Temperature (°C)

μ

551.6kPa655kPa724kPaTrendline (all)

37

Effect of Speed on Measured Horizontal Transverse Strain under HMA @ 25°C

y = 75.2e-0.0183x

R2 = 0.96

0

10

20

30

40

50

60

70

0 10 20 30 40 50 60 70 80Speed (km/h)

μstr

ain