Response and Performance Of Thin Bonded Rigid Overlays Subjected To Accelerated Pavement Testing

The 13th full-scale Accelerated Pavement Test (APT) experiment at the Civil Infrastructure Laboratory (CISL) of Kansas State University aimed at determining the response and failure mode of thin concrete overlays. Four pavement structures were built and tested in this experiment: 2 Thin Concrete Overlay (TCO) pavements, having 100 and 150 mm thick overlays constructed on top of a 125 mm thick PCCP and, 2 Thin Whitetopping (TWT) pavements, with 100 and 150 mm thick PCC overlays constructed on top of 125 mm hot-mix asphalt layer. The pavements were equipped with instrumentation to measure the strains at selected locations in each PCC overlay. Each of the 4 pavements was loaded with approximately 2 million passes of the CISL APT machine, under in-door ambient temperature conditions. No moisture was added to the pavements. Response measurements and performance evaluations were performed at about every 100,000 passes. Due to the effect of wheel loading, the TCO pavements failed due to the loss of support underneath the concrete slab. No loss of bond between the PCC overlay and the supporting slab was observed. The 100 mm TWT exhibited a transverse fatigue crack at the middle of the slab, while the 150 mm TWT exhibited no cracks at the end of testing. The theoretical strains in the concrete overlays at the locations were instrumentation was installed were computed with the ANSYS Finite Element Method (FEM) software. It was found that the magnitude and shape of computed strains matched well those of the strains measured before any APT loads were applied. It was, therefore, concluded that the 3-D finite element model built and the assumption made (linear elastic materials, fully bonded overlays) can estimate accurately the response of TWT and TCO pavements under wheel loading and therefore, can be used for predicting the performance of thin concrete overlays.