Field testing of concrete pavements at Chicago O'Hare International airport

In concrete pavements, differential temperature and drying gradients cause slabs to curl as shrinkage occurs. Internal stress in concrete is induced when slab corners lift off the ground, making the slabs susceptible to cracking under applied loads. In this study, concrete pavement instrumentation was employed to obtain pavement response data for the purpose of improving the understanding of slab behavior, which leads to confidence in pavement design. The sensor layout design incorporated the full suite of pavement sensors, including lift off gauges, joint opening gauges, and internal temperature and relative humidity sensors. Two testing projects were implemented: the preliminary testing at the Advanced Transportation Research and Engineering Laboratory (ATREL) test facility near the University of Illinois campus, and the field testing at the Chicago O'Hare International airport. In both tests, the expected cyclic diurnal variations and gradients with respect to depth from surface of the slab were observed. The pavement response data were collected and analyzed to infer stress and movement of the slab owing to environmental loads generated by temperature and moisture gradients. Those responses were also used to monitor the occurrence of cracking.