Design of Rigid Overlays for Airfields

Abstract

Current airfield overlay design generally uses empirical methods developed in the 1940s and 1950s. This paper presents a mechanistic overlay design procedure based on layered elastic theory as an alternative to the empirical design procedure. The layered elastic model is capable of analyzing layered structures with different material properties and interface conditions. It is also compatible with many current evaluation techniques using falling weight deflectometers. This mechanistic design approach includes the effects of fatigue and structural damage to the base pavement before overlay, progressive cracking of the base pavement after overlay, and substandard load transfer at joints. The proposed design procedure was checked against the results of the accelerated traffic tests originally used to develop the empirical overlay design equations, and comparative designs were also made using the proposed design procedure and the empirical equations. The proposed procedure generally gave good and reasonable comparisons with traffic test data, but the quantity of overlay test track data is limited. This analysis found that the current unbonded overlay equation is conservative; however, the partially bonded equation is not.