1. Field validation of constructed sub-grade and pavement
September 21, 2006
John S. Popovics
Jeffery Roesler
Marshall Thompson
David Lange
Robert Rodden
Yi-Shi Liu
Department of Civil & Environmental Engineering

2. Project Objectives
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.
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.

3. Work to date Pavement sensing (instrumented concrete slab)
NDE tasks
Saw-cut joints
10 inch pcc slab
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)

4. Concrete pavement instrumentation
Three types of sensors are embedded in the
concrete slab:
Relative humidity (RH) and temperature
(at a range of depths though the slab)
Slab lift-off (at slab corners)
Joint opening
On-site battery-powered data logger collects data

5. Sensor layout (plan view)
Instrumented concrete slab cast on June 22, 2006 at ATREL
Sensor layout (plan view)

6. Joint Opening Data
Dowel bars
No dowel bars

7. Lift-Off Data

8. RH profile

9. Temperature profile

10. Non-destructive tests (impact-echo)
Expected resonance at 8000 Hz for 10 inch slab
Dis-bonded region
Bonded region

11. Impact-echo thickness predictions
Data from bonded regions (hollow points)
Expected value
Data from dis-bonded regions (solid)
Inaccurate thickness predictions where pcc bonded to ac

12. 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)

13. Future work Pavement sensing
NDE tasks
Continue sensing and data collection in trial slab
to monitor longer term environmental effects, and
share data with other OMP projects
Incorporate sensors (similar layout) in actual O’Hare
slab cast in 2007 (R/W 9L section?)
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