Developing a Performance-Based Framework for the Analysis and Design of Unbound Granular Pavements

This research investigates rutting behaviour in flexible pavements constructed with unbound granular materials, which dominate Australia’s road network. Current design methods rely on simplified mechanistic–empirical approaches that do not fully capture the influence of stress state, material state, and climate conditions. Advanced laboratory testing, including Constant Radial Stiffness Triaxial tests and novel Radial Stiffness tests, was used to characterise material behaviour. An incremental rutting model was developed and integrated into pavement analysis, incorporating climate-driven moisture variations. The study demonstrates the applicability of performance-based design frameworks for predicting long-term performance and supports the development of cost-effective, structurally durable pavements.