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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. Project Objectives.
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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
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.
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)
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
Instrumented concrete slab cast on June 22, 2006 at ATREL Sensor layout (plan view)
No dowel bars Dowel bars Joint Opening Data
Non-destructive tests (impact-echo) Expected resonance at 8000 Hz for 10 inch slab Dis-bonded region Bonded region
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
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) Work to date Conclusions
Future work Continue sensing and data collection in trial slab to monitor longer term environmental effects, and share data with other OMP projects • Pavement sensing • NDE tasks 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