PREDICTION OF DAMAGE POTENTIAL ON ALASKAN HIGHWAYS DURING SPRING THAW USING THE FALLING WEIGHT DEFLECTOMETER. FINAL REPORT

Benkelman Beam data have been widely used to design overlays and establish load restrictions. However, research carried out in Alaska has shown that gross errors can occur from its use 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 develooped to determine the damage potential and thaw depth based on Falling Weight Deflectometer (FWD) tests. This method adjusts the measured center deflection to the deflection which would have been obtained had no frozen materials been present in the pavement structure. This adjusted FWD deflection is essentially equivalent to the traditional Benkelman Beam deflection (for relatively thin asphalt-surfaced pavements, at the same test load) so that conventional methods may be used to design overlays and establish load restrictions.