Design of Rigid Overlays for Airfield Pavements
Rollings, Raymond Sydney
Witczak, Matthew W.
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Existing rigid overlay pavement design methods are empirical and use a specified level of cracking as the defined failure condition. The existing empirical designs are based on tests run thirty years ago, and current analytical models provide greatly improved abilities to examine the overlay pavement structure. Emphasis by many agencies on life cycle cost analysis and more sophisticated maintenance and rehabilitation strategies require methods of predicting pavement performance rather than simply developing safe designs. A layered elastic analytical model was selected to evaluate stresses from applied loads in the pavement structure. Pavement performance was measured in terms of a Structural Condition Index which related the type, degree, and severity of pavement cracking and spalling on a scale of 0 to 100. Models were developed to represent the effect of cracking in base slabs under the overlay, to account for fatigue damage of previous traffic on the base pavement, and to account for the effects of substandard load transfer at slab joints. The predicted performance of overlays and pavements using this analysis was checked against the results of full-scale accelerated traffic tests conducted by the Corps of Engineers and against current overlay design methods and was found to provide reasonable agreement. This methodology using the layered elastic analytical model and analysis of fatigue and cracking in the base slab provides a method of predicting pavement and overlay deterioration in terms of a Structural Condition Index.