Three-dimensional analytical model for exploration of the block cracking phenomenon in asphalt pavements

Block cracking is a common type of distress in asphalt pavements, which can be found in a variety of climatic and geographical locations. The extensive nature of this cracking form often leads to significant maintenance costs and reduces the ride quality and service life of the pavement surface. Although this deterioration mode is covered in many pavement evaluation guides and condition rating systems, the underlying mechanisms of block cracking have not been fully investigated. This is likely because the phenomenon requires a three-dimensional (3D) fracture analysis to be conducted to capture the structural response associated with this complex cracking form. Computational fracture modelling and simulation will ultimately be needed to explore the detailed thermal and material gradients, time dependencies and nonlinearities associated with this 3D cracking phenomenon. However, it is first necessary to develop rigorous closed-form, analytical solutions to serve as benchmarks for the verification of future 3D numerical simulation results. In addition, the reference analytical solutions provide preliminary new insights into the mechanisms of block cracking. This study presents a 3D, analytical elastic model of a two-layer pavement system subjected to constant thermal stresses. Analytical solutions of displacement and stress fields are presented in the equation and graphical form and new insights towards the mechanisms of block cracking are discussed. The use of the model as a tool to verify numerical solutions, such as finite element analyses is also discussed. Illustrative examples a field validation example and a summary of required model extensions are also provided.