In recent years environmental sustainability has demanded a progressive increase of waste recycling in general and waste value-added utilisation in the construction industry in particular. As regards the application of construction and demolition wastes (C&DW) in geotechnical works, it has been noticed that the use of recycled aggregates is found mostly in road construction. Value-added utilisation of C&DW in geosynthetic-reinforced structures is almost an unexplored field. This paper presents the results of physical, mechanical and environmental characterisation of recycled C&DW, as well as the direct shear behaviour of three recycled C&DW–geosynthetic interfaces. The C&DW material was collected from a recycling plant and came from the demolition of single-family houses and the cleaning of land with illegal deposits of C&DW. Two geogrids and one geocomposite reinforcement (high- strength geotextile) were used to assess the behaviour of C&DW–geosynthetic interfaces. The environmental characterisation of the C&DW, carried out through leaching tests, did not show environmental concerns. Direct shear test results have demonstrated that properly selected and compacted C&DW can exhibit shear strength similar to natural soils. The coefficients of interaction achieved for C&DW–geosynthetic interfaces compare well with those reported in the literature for soil–geosynthetic interfaces under similar conditions, which supports the feasibility of using these recycled materials as backfill in geosynthetic-reinforced structures.

The construction industry is one of the biggest sectors of economic activity in the European Union, consuming more energy and natural resources than any other industrial activity. Additionally, construction and demolition (C&D) waste is the most common waste produced throughout the European Union. A more efficient and effective use of natural resources and the attenuation of environmental impacts provoked by their extraction could be accomplished if correct construction and demolition waste management and recycling policies were implemented. The use of recycled C&D waste in road pavement layers is a solution with economic and environmental benefits that has been widely studied in recent decades. This paper provides a literature review on the relevant engineering properties of different types of recycled aggregates coming from C&D waste, a comparison with the properties of natural aggregates, and how these recycled aggregates perform in the long-term when used in unbound pavement applications. An analysis of the current status of C&D waste generation and recovery practices in the European Union is also presented. The aim of this review is to further encourage the use of recycled materials coming from C&D waste, particularly in unbound pavement applications, since, in general, research conducted worldwide has proven their good performance in the short and long-term.