Effective maintenance of a concrete pavement requires precise evaluation of the load transfer efficiency (LTE) at the transverse joint, which is simply calculated from the falling weight deflectometer (FWD) deflections at the loaded and unloaded slabs. In this study, the FWD deflections were simulated with the randomly generated elastic moduli of the pavement layers using the three dimensional finite element method considering the degradation process at a joint, which was categorized into five stages, from completely sound, to having broken dowels and a void underneath the joint. A database of FWD deflections, layer elastic moduli and the associated stage was created from the simulation results. The layer moduli were identified from the measured FWD deflections at a joint by searching the closest calculated FWD deflections to those measured from the database. The results of the analysis not only provide the layer moduli, but also the degradation stage of the joint to help engineers determine the appropriate rehabilitation measures. The method was validated on a 16 year old concrete pavement, on which the FWD measurements were performed three times: just before opening to traffic, after 9 years and 16 years of service. The identified layer moduli were not changed after 16 years of service, and some joints degraded owing to dowel corrosion, broken dowels and the existence of voids underneath the joints. The developed method is able to show the entire picture of the state of the joints in a section and also provide information on which parts of a particular joint have deteriorated.
STRUCTURAL EVALUATION OF TRANSVERSE JOINT OF 30 YEARS CONCRETE PAVEMENT ON EXPRESSWAY WITH FWD BACKCALCULATION
