| The objective of this study is to investigate the thin concrete overlay performance and the effects of bonding on that performance. A sufficient bonding between concrete overlay and existing pavement is one of the factors affecting the pavement performance. In order to characterize the performance of overlay and bonding, a field survey, laboratory experiment and FEA analyses were carried out.; First, a field evaluation of both bonded and unbonded pavement test sections in Iowa was performed. Initially, a pavement surface condition survey was performed. Then, cores were extracted from the existing pavements and tested for their bond strengths. It was found that a proper bonding condition, surface preparation of existing pavement, overlay construction and overlay material provided reasonable bond strength.; Second, both bonded and unbonded concrete cylinders using polymer and regular concrete were fabricated to measure the bonding strength. The laboratory experiment showed the polymer concrete samples exhibited higher bonding strength than the regular concrete samples.; Third, a 3D FEA model using a spring element was developed to quantify the bond level. This model simulated the various bonding levels from fully bonded to unbonded condition by changing the stiffness of spring element. A parametric study was conducted by changing the spring stiffness to develop a matrix that can be used to determine the spring stiffness to model the different bonding levels.; Finally, a 3D FEA pavement model including a concrete element was used to investigate the concrete overlay performance based on the first crack formation in the concrete slab. A parametric study was carried out to find what factors affected the first crack formation. It was found that the overlay deterioration level and thickness significantly affected the first crack formation. Then, using these factors, an overlay life expectancy was estimated, which can be used to predict the future pavement performance. |
