Unbound road pavements are commonly used in arterial and low-volume roads. In Australia, these pavements amount to about 90% of the sealed road network. They comprise layers of unbound materials like crushed rock placed over prepared subgrade soils. An asphalt or bitumen layer is typically placed on top to provide sealing and riding conditions. The primary distress mode for these pavements is excessive rutting, which arises from the vertical plastic deformation from the unbound and subgrade layers. These plastic deformations occur primarily from volumetric and shear deformation accumulation due to cyclic stresses induced by traffic loads. The performance of these layers depends heavily on the density and degree of saturation of these materials, signifying the critical importance of unsaturated soil mechanics.

Furthermore, these parameters can change during operation, especially the degree of saturation due to interaction with the prevailing climate, depending on the seal permeability. Unfortunately, due to the complexity of these processes, predominantly empirical approaches are employed to design these pavements. In particular, there is a significant disconnect between testing, design, and construction of these pavements, which hinders reaping benefits from digitalisation, such as using digital twin concepts.

Drawing on insights from research undertaken at the Australian Research Council (ARC)’s Industry Transformation Research Hub for Smart Next Generation Transport Pavements (SPARC Hub), this keynote presentation delves into the comprehensive integration of pavement testing, design, and intelligent construction of unbound road pavements with thin asphalt seals. It will introduce an innovative testing methodology referred to as the Constant Radial Stiffness Triaxial Test, a more rational design approach incorporating climate effects into pavement design and integrated intelligent construction techniques. By leveraging advanced unsaturated soils concepts and data-driven insights, it is considered that unbound pavement technology can contribute to more resilient, sustainable, and efficient road networks.

Professor Jayantha Kodikara is the Director of ARC Hub for Smart Next Generation Transport Pavements – SPARC (www.sparchub.org.au) within Monash Civil Engineering. He is also the leader of Monash Pipeline Research Group. He has published over 500 publications on diverse topics and has graduated over 50 PhD students. He is a Chartered Professional Engineer in Australia and a Fellow of Engineers Australia. His fundamental research has led to the development of the MPK (Monash-Peradeniya-Kodikara) Framework and Model for unsaturated compacted soil modelling, which uncovered a direct link between the traditional compaction curve and advanced unsaturated soil modelling. Seminal contributions in the applied research area include elucidating buried water pipe failure and deterioration mechanisms, leading to global paradigm shifts in pipeline asset management. He has received several awards for innovation and industry collaboration, including National and International Water Association Awards and B/HERT Award in 2016, ARRB Impact Award in 2019, and Monash Vice-Chancellor’s and Dean’s Awards for Innovation and Enterprise in 2019 and in 2013.