Innovative materials for sustainable road pavements: recycling and performance from subgrade to surface layer

The road construction sector is implementing major developments in line with sustainability strategies and policies to address environmental, economic and social impacts across the life cycle of road pavements. It is vital that strategies for the reuse of recycled materials are developed and promoted, with particular attention paid to mixture design and material performance to reduce construction and maintenance interventions. The goal of this research is to provide a comprehensive analysis of the feasibility and applicability of high percentages of recycled materials in transport infrastructure, with a particular focus on high-performance road pavements. Multiple recycled materials have been characterised and designed in laboratory to develop solutions for application across road structure layers in order to evaluate the potential for reuse in sustainable, high-quality and durable pavements. The analysis investigates the valorisation of dredged sediments as a new resource for road subgrade and the design of asphalt concrete mixtures containing Reclaimed Asphalt Pavement (RAP) and steel slag for wearing courses with improved mechanical performance. The design of durable pavements requires the evaluation of the pavement response at critical points of investigation to assess the structural distresses and minimise the damage to the pavement over its service life. The implementation of advanced software for modelling and designing road pavement infrastructure simplifies the process of developing solutions that are safe, efficient, and environmentally sustainable. The performance prediction of infrastructure solutions with high percentages of recycled materials in the different constituent layers through the implementation of road design software based on the continuum finite-layer approach is presented. The materials analysed in this research exhibited mechanical responses comparable to those observed in traditional mixtures. The investigation of solutions comprising recycled materials that simultaneously exhibit superior mechanical performance represents a fundamental initiative towards sustainability.