The Development of Asphalt Mix Creep Parameters and Finite Element Modeling of Asphalt Rutting
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Asphalt pavement rutting is one of the most commonly observed pavement distresses and is a major safety concern to transportation agencies. Millions of dollars are reportedly spent annually to repair rutted asphalt pavements. Research into improvements of hot-mix asphalt materials, mix designs and methods of pavement evaluation and design, including laboratory and field testing, can provide extended pavement life and significant cost savings in pavement maintenance and rehabilitation. This research describes a method of predicting the behaviour of various asphalt mixes and linking these behaviours to an accelerated performance testing tool and pavement in-situ performance. The elastic, plastic, viscoelastic and viscoplastic components of asphalt mix deformation are also examined for their relevance to asphalt rutting prediction. The finite element method (FEM) allows for analysis of nonlinear viscoplastic behaviour of asphalt mixes. This research determines the critical characteristics of asphalt mixes which control rutting potential and investigates the methods of laboratory testing which can be used to determine these characteristics. The Hamburg Wheel Rut Tester (HWRT) is used in this research for asphalt laboratory accelerated rutting resistance testing and for calibration of material parameters developed in triaxial repeated load creep and creep recovery testing. The rutting resistance criteria used in the HWRT are developed for various traffic loading levels. The results and mix ranking associated with the laboratory testing are compared with the results and mix ranking associated with FEM modeling and new mechanistic-empirical method of pavement design analyses. A good relationship is observed between laboratory measured and analytically predicted performance of asphalt mixes. The result of this research is a practical framework for developing material parameters in laboratory testing which can be used in FEM modeling of accelerated performance testing and pavement in-situ performance.