Determining Effects of Layer Bonding and De-Bonding on Perpetual Pavements

This study investigates de-bonding of asphalt concrete (AC) layers in flexible pavements and determines how de-bonding affects the performance of these pavements using mechanistic models. At present, all flexible pavement design methods assume that there is complete bonding between all AC layers. In complete bonding conditions, the strain at the base of the asphalt layer are transferred to the asphalt layer below, and the displacement at these locations is equal. These assumptions are made to facilitate the modeling of AC pavements. However, in reality, these assumptions are not completely satisfied. Materials in each layer are not identical so the response to traffic loading is different. Using complete bonding conditions in flexible pavement design thus reduces design reliability due to increasing traffic volumes, traffic speed, and tire pressure. Current mechanistic-empirical analysis shows that 90% of the pavements presented in this study fail by top-down cracking if de-bonding occurs between the AC layers. Bottom-up cracking and AC rutting also increase significantly in de-bonded environments. This study recommends the development of a model that accounts for partial bonding/de-bonding in flexible pavement design.