USE OF THE FALLING WEIGHT DEFLECTOMETER TO PREDICT DAMAGE POTENTIAL ON ALASKAN HIGHWAYS DURING SPRING THAW

Benkelman beam data have been widely used to design overlays and establish load restrictions. However, research carried out in Alaska has shown that their use can result in gross errors in areas where freeze-thaw conditions prevail. It has long been known that the shape of the deflection basin is related to the life of the pavement. As a result, a method has been developed to determine damage potential and thaw depth based on tests with falling weight deflectometer (FWD). This method adjusts the measured center deflection to the deflection that would have been obtained had no frozen materials been present in the pavement structure. Because this adjusted FWD deflection is essentially equivalent to the traditional Benkelman beam deflection (for relatively thin asphalt-surfaced pavements at the same test load), conventional methods can be used to design overlays and establish load restrictions.