Study of multi-material bituminous surface applications, in multilayer or mixture, for thin and ultra-thin functional layers

In recent decades, road infrastructure preservation has increasingly prioritized preventive maintenance over traditional reconstruction, offering a sustainable and cost-effective approach to managing road networks. Thin and ultra-thin bituminous surface applications are essential in this context, as they restore pavement functionality and extend service life while minimizing the consumption of virgin resources. Despite their benefits, the lack of uniform assessment criteria often hinders their integration into common practices. This research addresses these gaps by focusing on the optimization and characterization of multi-material thin-layered functional systems, utilizing an extensive experimental campaign and recycled materials to enhance sustainability. The investigation first introduces a novel contactless methodology based on Close-Range Photogrammetry for assessing road surface status. By employing spectral decomposition of texture profiles, the study correlates specific wavelengths with key functional properties, providing a more reliable alternative to empirical testing. Building on this, the research explores microsurfacings, optimizing mix-design procedures and introducing a pioneering laboratory protocol for evaluating bonding resistance through a direct shear procedure. Long-term durability was further assessed using a prototype traffic simulator and advanced surface analyses. Furthermore, the study evaluates Ultra-Thin Porous Asphalt systems designed to mitigate urban surface runoff. The inclusion of Electric Arc Furnace slags demonstrated enhanced fatigue and rutting performance, while laser-based topological analyses clarified the role of air-void interconnectivity. Finally, these expertise were extended to hydraulic constructions through Modified Bitumen Sealing Membranes, providing waterproofing and solar protection for asphalt-facing dams. Collectively, this work demonstrates that thin-layered bituminous materials are high-performance, sustainable solutions, offering scientifically grounded tools to advance the design and monitoring of durable modern infrastructures.