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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?)