RESPONSE AND PERFORMANCE OF CONTINGENCY AIRFIELD PAVEMENTS CONTAINING STABILIZED MATERIAL LAYERS

The mechanistic approach for the design and evaluation of Contingency Airfield Pavements (CAPs) containing stabilized material layers was validated. CAPs are inexpensive pavements built in peacetime and available immediately after an attack for limited aircraft operations. The mechanistic approach was validated by relating predicted first pass structural response parameters (stress and strain) to observed field performance.;Stabilized material layer modulus was back-calculated using the FWD data. First pass predicted structural response was determined using ILLI-PAVE, a stress dependent finite element computer program, and ILLI-SLAB, a finite element computer program for rigid pavements with cracks or joints. The test items were thin by conventional design standards and had predicted first pass stress ratios in the stabilized material layers greater than one. Item performance was divided into three phases explaining the development and propagation of the observed cracks. Transfer functions were developed relating predicted first pass crack stress or strain ratios to passes to functional failure.;Major study findings included: (1) Subgrade characteristics control performance in pavements with predicted first pass crack stress ratio greater than one. (2) CAPs should be designed and evaluated using an intact slab concept. (3) Design of CAPs should be based on stress or strain ratios less than one. (4) The presence of a crushed stone base course over a stabilized subbase course in an inverted pavement has a bridging effect at transfer cracks in the stabilized subbase and inhibits the rate of crack propagation to the surface. (5) In an inverted pavement, the thickness of the stabilized subbase is more effective in controlling the stress in the subbase than the thickness of the stone base course.;Eleven CAP test items were constructed; eight two-layer items containing a rigid cement aggregate mixture and two inverted pavement items containing stone base and stabilized subbase courses. Items were subjected to simulated channelized F-4 main gear traffic using a load cart. Field data analyzed in this report included Falling Weight Deflectometer (FWD) load-deflection data, surface cracking and profile measurements, and item center pass deflection and cumulative permanent deformation.