Consequence of Layer Separation on Pavement Performance

摘要

Asphalt concrete (AC) and portland cement concrete (PCC) pavements were investigated to determine the consequence of overlay separation on pavement behavior. Available methods of detection and rehabilitation of layer separation were addressed. Stresses and strains resulting from aircraft loading in an AC pavement section were computed by layered elastic theory. Layer slippage and consequent separation generates large tensile strains at the bottom of the slipped layer, resulting in reduced fatigue life. Horizontal tangential loads due to braking or turning generate high tensile strains at the top of the overlay just outside the wheel imprint which are likely to be critical even when layer separation is not present. A pavement where interlayer slippage has occurred should be repaired by removing the slipped layer and replacing it with a well-bonded layer. A finite element model was used to evaluate PCC pavement response to load, and Westergaard/Bradbury equations were used to determine curling stresses. It was found that loss of bond adversely affects maximum pavement tensile stress (thus fatigue life) and maximum pavement deflections. It is also believed that curling stresses may cause debonded thin overlays to separate from the underlying slab, causing extremely high stress in the overlay if a load is applied. Bond can be obtained only if good construction techniques are followed. Detection of bond loss may be possible using corner deflections determined by nondestructive testing. Keywords: Runways; Structural analysis.