The proper use of natural resources is one of the fundamental pillars of sustainable development imposed on modern societies. A more effective and efficient use of natural resources, as well as the mitigation of environmental impacts induced by their extraction could be achieved if proper management and recycling policies of Construction and Demolition (C&D) wastes were implemented. The valorisation of wastes in the construction industry is needed and is a way toward sustainability. This paper provides a literature review on studies related to the valorisation of Construction and Demolition (C&D) materials in geotechnical engineering applications, with an emphasis on their use as recycled aggregates in base layers of roadway infrastructures and as filling material for geosynthetic reinforced structures. Specifications that should be followed when these materials are used in such projects are also summarised. With this review it is intended to promote the use of recycled C&D materials, showing that research carried out all over the world has demonstrated their good performance in general.

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In recent years environmental sustainability has demanded a progressive increase of waste recycling in general and waste value-added utilization 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 utilization of C&DW in geosynthetic reinforced structures is almost an unexplored field. This paper presents results of physical, mechanical and environmental characterization 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 characterization 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.

In recent years, environmental concerns related to the overexploitation of natural resources and the need to manage large amounts of wastes arising from construction activities have intensified the pressure on the civil engineering industry to adopt sustainable waste recycling and valorisation measures. The use of recycled construction and demolition (C&D) wastes as alternative backfill for geosynthetic-reinforced structures may significantly contribute towards sustainable civil infrastructure development. This paper presents a laboratory study carried out to characterise the interaction between a fine-grained C&D material and two different geogrids (a polyester (PET) geogrid and an extruded uniaxial high-density polyethylene (HDPE) geogrid) through a series of large-scale pullout tests. The effects of the geogrid specimen size, displacement rate and vertical confining pressure on the pullout resistance of the geogrids are evaluated and discussed, aiming to assess whether they are in line with the current knowledge about the pullout resistance of geogrids embedded in soils. Test results have shown that the measured peak pullout resistance of the geogrid increases with the specimen size, imposed displacement rate and confining pressure. However, the pullout interaction coefficient has exhibited the opposite trend with the specimen size and confining pressure. The pullout interaction coefficients ranged from 0.79 and 1.57 and were generally greater than or equal to the values reported in the literature for soil-geogrid and recycled material-geogrid interfaces.

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