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Field validation of Field validation of constructed sub-grade constructed sub-grade

and pavementand pavement

John S. PopovicsJohn S. PopovicsJeffery RoeslerJeffery Roesler

Marshall ThompsonMarshall ThompsonDavid LangeDavid Lange

Robert RoddenRobert RoddenYi-Shi LiuYi-Shi Liu

Department of Civil & Environmental Engineering

September 21, 2006September 21, 2006

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Project Objectives

The output data from the sensors will be used to infer stress and movement of the slab owing to temperature and moisture gradients. Those responses will be used as input for other OMP research projects.

The NDT findings will be used to develop new test methods that provide more appropriate and effective performance at the OMP site.

Obtain response data and non-destructive test (NDT) test results from a test structure that replicates the nominal design

to be used in the O’Hare modernization program.

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Work to date Pavement sensing (instrumented concrete slab)

NDE tasks

10 inch pcc slab

Saw-cut joints

16 inch dense AC base

NDT applied to determine in place thickness and/or material properties of pavement layers.

Impact-echo and surface wave methods (SASW, MASW)

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Concrete pavement instrumentation• Relative humidity (RH) and temperature

(at a range of depths though the slab)

• Slab lift-off (at slab corners)

• Joint opening

Three types of sensors are embedded in the concrete slab:

On-site battery-powered data logger collects data

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Sensor layout (plan view)

Instrumented concrete slab cast on June 22, 2006 at

ATREL

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Joint Opening Data

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

6/17 6/22 6/27 7/2 7/7 7/12 7/17

DATE

JOIN

T-O

PE

NIN

G (

in)

A

B

C

D

AC

BD

Dowel bars

No dowel bars

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Lift-Off Data

0

0.005

0.01

0.015

0.02

0.025

0.03

6/17 6/22 6/27 7/2 7/7 7/12 7/17

DATE

LIFT

-OFF

(in)

No Dowel Bars (East Joint)

Dowel Bars (West Joint)

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RH profile

10

20

30

40

50

60

70

80

90

100

14 15 16 17 18 19 20 21 22

days

RH

(%

)

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Temperature profile

10

15

20

25

30

35

40

14 15 16 17 18 19 20 21 22

days

Tem

per

atu

re (

C )

'

10Bonded regionDis-bonded region

Non-destructive tests (impact-echo)Expected resonance at 8000 Hz for 10 inch slab

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0.2

0.25

0.3

0.35

0.4

0.45

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Age (days)

Th

ick

ne

ss

(c

m)

Impact-echo thickness predictions

Expected value

Inaccurate thickness predictions where pcc bonded to ac

Data from bonded regions (hollow points)

Data from dis-bonded regions (solid)

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Work to date Conclusions Useful data for field verification of the

constructed pavement layer have been collected. The sensor layout was effective. Most sensors functioned adequately, but lift-off sensor design should be improved.

Conventional NDT tests may not work suitably for OMP pavement structure (dense asphalt base)

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Pavement sensing

NDE tasks

Future workContinue sensing and data collection in trial slabto monitor longer term environmental effects, and share data with other OMP projects

Modify or develop new NDT methods for estimation of

layer properties and thickness that will work on O’Hare

pavement: modified impact-echo and MASW. Tests

Developed at ATREL, verified at O’Hare

Incorporate sensors (similar layout) in actual O’Hare slab cast in 2007 (R/W 9L section?)