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

Abstract

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.

Keywords:

• interface
• accelerated testing
• finite element
• hot-mix asphalt
• Portland cement concrete

Acknowledgements

This publication is based on the results of ICT-R55, Tack Coat Optimisation for HMA Overlays. ICT-R55 was conducted in cooperation with the Illinois Center for Transportation (ICT); the Illinois Department of Transportation (IDOT), Division of Highways and the US Department of Transportation, Federal Highway Administration.

The authors would like to acknowledge the assistance of David Lippert, IDOT's Engineer of Materials and Physical Research and the following members of the Technical Review Panel for ICT-R55: James Trepanier (Chair), Amy Schutzbach, Charles Weinrank, Patty Broers, Terry Hoekstra, Derek Hoekstra and Tom Winkelman.

The contents of this paper reflect the view of the authors, who are responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the ICT and the IDOT. This paper does not constitute a standard, specification or regulation. Trademark or manufacturers' names appear in this paper only because they are considered essential to the object of this document and do not constitute an endorsement of product by the ICT or the IDOT. In addition, this work was partially supported by the National Center for Supercomputing Applications (NCSA) under project # TG-ECS090012 and utilised the NCSA Dell Intel 64 Cluster Abe and Cobalt machine.

Notes

^† Present address: Rutgers, The State University of New Jersey, 623 Bowser Road, Piscataway, NJ 08854, USA