Characterisation of interface bonding between hot-mix asphalt overlay and concrete pavements: Modelling and in-situ response to accelerated loading

This study investigates the effects of pavement interface conditions on hot-mix asphalt (HMA) overlay response using the laboratory and field measurements accompanied by a numerical analysis. A laboratory and accelerated testing programme were conducted as part of a comprehensive study to determine the optimum tack coat application rate for HMA-Portland cement concrete (PCC) composite pavements by Leng et al. (2008, Transportation Research Record: Journal of the Transportation Research Board, 2057, 46-53; 2009, Transportation Research Record: Journal of the Transportation Research Board, 2127, 20-28). This study synthesises the accelerated and laboratory test results with a 3D finite element (FE) model to evaluate the effects of various bonding conditions on the overlay response as well as the interface behaviour. The model outcome was validated using the laboratory and field results. The FE model was utilised to extend the findings of this study to different temperatures, tyre configurations and loading conditions. Pavement interface was modelled using a hyperbolic Mohr-Coulomb friction model, whereas HMA overlay was modelled as a viscoelastic material. A moving load was applied and implicit dynamic analysis was carried out. Field and laboratory experiments along with the numerical analysis proved the importance of achieving good bonding at the pavement interface for HMA overlay. This study found that as pavement temperature increases, the interface bonding effects on the overlay response are amplified. This could be the main contributing factor to overlay rutting. The influence of interface condition on the HMA surface and bottom strains was evaluated using a numerical model supported by full-scale accelerated pavement testing results. The effects of varying interface properties such as stiffness and strength on the HMA overlay response were investigated. The numerical model provided a range of expected HMA critical strains under realistic interface conditions ranging from full bonded to debonded conditions. This study clearly shows the significance of tack coat type and application rate effects on pavement critical responses through laboratory, in-situ response and advanced modelling.