Visiting Researcher: Dr Didier Bodin

Premature rutting of asphalt pavements still represents a serious practical problem for heavily trafficked roads, particularly under high temperature conditions. Over the years a number of different approaches have been used for the prediction of permanent deformation in flexible pavement structures. One of the limitations associated with the more sophisticated techniques is that application to practical pavement problems requires implementation of the constitutive model in a Finite Element (FE) framework. This has limited the applicability of these more complex models and to-date no accepted methodology is used in the UK.In April 2004, EPSRC funded a 3-year project at Nottingham entitled Development and FE Implementation of a Non-Linear Constitutive Model for Asphalt (GR/S56818/01). The aim of this project is to further develop and validate a non-linear elasto-visco-plastic constitutive model for asphalt with visco-plastic damage so that permanent deformation in the asphalt layers of a pavement structure under traffic loading can be predicted with reasonable accuracy. As part of this project, an extensive programme of laboratory testing is currently being undertaken as well as a comprehensive programme of model development and implementation. Simulative wheel loading tests are being undertaken and full-scale trials under controlled conditions are planned for Spring 2006 which will serve as validation test cases for the model.Over the last few years, much research has been undertaken in the LCPC pavement division related to rutting of asphalt pavements. A three-dimensional elasto-viscoplasticity model has been developed and applied to describe the behaviour of asphalt under cyclic loading. The model has been implemented into the Csar-LCPC Finite Element (FE) software developed by LCPC. The aim of this proposal is to seek funding to bring Dr Didier Bodin to NCPE as a Visiting Researcher for a period of 12 months to work alongside the current EPSRC project on constitutive modelling of asphalt. The large amount of experimental data generated from the current project will be used to calibrate/evaluate the constitutive model developed by LCPC and predictions will be compared to those from the model being developed by Nottingham and Delft as part of the current project.