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Field validation of constructed sub-grade and pavement

Field validation of constructed sub-grade and pavement. July 20, 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

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Field validation of constructed sub-grade and pavement

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  1. Field validation of constructed sub-grade and pavement July 20, 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. 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

  4. Relative humidity/temp sensors • Sensirion SHT75 • Single sensor measures RH and Temperature • RH accuracy +/- 1.8% • Temp accuracy +/- 0.3% • Sample at depths ½”, 1”, 2”, 3”, 5”, 7” and 8½” for complete depth profile • Sensors used and proven reliable by UIUC

  5. Slab lift-off gauges • Modified LVDT • Tip affixed to base material under slab • LVDT mounted in chamber that is bonded to concrete • Used by FAA R&D Division (NAPTF) • Resolution 1.0-2.0 microns

  6. Joint opening gauges • Surface-mounted LVDTs • LVDT and reaction platen affixed to the top of slab across joint near edge • Resolution 1.0-2.0 microns

  7. Data loggers & multiplexers • On-site battery-powered data logger developed at UIUC (Campbell Scientific) • Sensor multiplexer used and proven reliable by UIUC

  8. Instrumented concrete slab cast on June 22, 2006 at ATREL (Rantoul, IL) Saw-cut joints 10 inch pcc slab 16 inch dense AC base

  9. Sensor layout (plan view)

  10. Sensor locations

  11. No dowel bars Dowel bars Joint Opening Data

  12. Lift-Off Data

  13. RH profile

  14. Temperature profile

  15. May not work for pcc over ac base Non-destructive Tests NDT applied to determine in place thickness and/or material properties of pavement layers. • Impact-echo (IE) and seismic methods • Surface wave methods (SASW and MASW) • determine slab thickness • locate internal delamination or voiding • determine pavement layer structure profile • (thickness and stiffness)

  16. Impact-echo results Expected resonance at 8000 Hz for 10 inch slab Dis-bonded region Bonded region

  17. 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

  18. Useful data for field verification of the constructed pavement layer are being collected. The sensing will continue to monitor longer term effects of the environment. Conventional NDT tests may not work suitably for OMP pavement structure. We aim to modify or develop new NDT methods that will work. Summary

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