EVALUATION OF BEARING CAPACITY OF EXISTING ASPHALT PAVEMENT USING FALLING WEIGHT DEFLECTOMETER . THIRD INTERNATIONAL CONFERENCE ON BEARING CAPACITY OF ROADS AND AIRFIELDS. PROCEEDINGS, NORWEGIAN INSTITUTE OF TECHNOLOGY, TRONDHEIM, NORWAY, JULY 3-5 1990. VOLUMES 1-2

This paper describes a method for evaluating a structural capacity of existing asphalt pavements using deflection data obtained by the falling weight deflectometer. A back analysis was applied to estimate in situ elastic moduli of granular subbase and subgrade in the pavements. A tensile strain generated at the bottom of asphalt layer and a compressive strain generated in the subgrade surface under a standard wheel load were calculated with the BISAR. The number of allowable loading repetitions corresponding to the tensile strain and the compressive strain were estimated with asphalt strain criteria and subgrade strain criteria provided by many researchers. The relationships between the calculated tensile strain and the total amount of 50kN equivalent wheel load applications in service were obtained at six sections with different asphalt pavement structures in National Highway Route 337 in Hokkaido prefecture. Amount of cracking, rut depth and longitudial roughness on the highway were measured by an automatic pavement distress survey vehicle. The number of load repetitions to failure estimated with the asphalt strain criterion was closely connected with the cracking in each section. The asphalt strain criteria are useful information on mechanistic approach for the designs of new pavements and overlay, because there are close relationships between cracking and the estimated number of load reptitions to failure at each section in the highway. (Author/TRRL)