COMPARATIVE STUDY OF PAVEMENT RESPONSE TO FWD AND AXLE LOADINGS . THIRD INTERNATIONAL CONFERENCE ON BEARING CAPACITY OF ROADS AND AIRFIELDS. PROCEEDINGS, NORWEGIAN INSTITUTE OF TECHNOLOGY, TRONDHEIM, NORWAY, JULY 3-5 1990. VOLUMES 1-2

The response of flexible pavements to 100-KN single axle and Falling Weight Deflectometer (FWD) loadings was investigated. A Benkelman beam (BB) was used to measure surface deflection basin under the axle loading. The FWD and BB were compared side-by-side on five experimental pavements, including four asphalt concrete pavements and one crushed rock pavement. Comparisons of the deflection basins and the deflection variations within pavement of test sections are made. Equations correlating deflections from FWD with the BB measurements are presented. Finally, the pavement layer moduli are determined by interpretations of measured surface deflection basins. In this process, a methodology in which the regression approach is used to estimate the initial moduli and the backcalculation is used to obtain the final estimated moduli has been developed to ensure the uniqueness of the insitu moduli. Results of the study indicate that the moduli of various layers evaluated from the FWD deflection basins are not exactly equal to those obtained from the BB deflection basins. (TRRL)