Characterizing Mechanical Responses of Composite Pavements in Falling Weight Deflectometer Testing for Structural Condition Evaluation

Abstract

Evaluating the structural condition of composite pavements (i.e., flexible over rigid) is crucial for pavement management systems, which are significantly affected by mechanical responses in the joints of Portland cement concrete (PCC) slabs. However, limited research is concentrated on the effects of PCC joints on the composite pavement mechanical responses in falling weight deflectometer (FWD) testing. In this study, the aim is to develop a practical method for evaluating the structural condition of composite pavements using FWD testing. The proposed method utilizes deflection basin parameters (DBPs) to identify the position of a PCC slab joint and estimate the depth of reflective cracking. The mechanical responses in FWD testing were characterized using finite-element models, and correlations between the DBPs and critical mechanical responses were analyzed. The results were verified using field data sets collected from routine surveys in Indiana. The research indicates that the mechanical responses at the bottom of the asphalt layer present the second fluctuation (SF) caused by the PCC joint in FWD testing. The extreme values of normal and shear strain in the SF can be used as critical mechanical responses to identify the PCC joint and evaluate reflective cracking. When the reflective cracking depth reaches 75% of the asphalt layer thickness, the shear strain increases sharply. The adjusted base damage index and surface curvature index are correlated with the extreme values of normal and shear strains, respectively. This correlation enables recognition of PCC joints and estimation of reflective cracking in composite pavement based on FWD testing.