Use of mixed recycled aggregates with a low embodied energy from non-selected CDW in unpaved rural roads

This paper evaluates the behaviour and the environmental impact of a mixed recycled aggregate from non-selected construction and demolition waste (CDW) in field conditions. For this purpose, one experimental unpaved rural road with two sections was built. Sections were formed with a poor subgrade (A-6) and two structural layers: the first section consisted of a base course and a surface built using a natural aggregate and a low quality mixed recycled aggregate, respectively, and the second section, which was used as a reference, consisted of a soft crushed limestone aggregate. The materials were previously characterised in the laboratory. Control compaction ensured that the materials were correctly set in place, and the bearing capacity of each fill layer was measured. The structural performance of the pavement was determined using a falling weight deflectometer, and the changes in the international roughness index and the bearing capacity over time were studied. The results show that the non-selected CDW can be recycled using a simple treatment to create low quality recycled material with a low embodied energy that can be used as an alternative to natural aggregates in unpaved rural roads. According to the technical specifications, the total sulphur compound (SO3) and the soluble salts content can rise to 3.9% and 3.3%, respectively, without posing a sulphate leaching risk or a reduction in the quality of this type of work. This study is important for increasing recycling rates of non-selected CDW and will support sustainable development in the building sector.

► A recycled aggregate from non-selected CDW has been evaluated in field conditions.
► One experimental unpaved rural road with two sections was built.
► Mixed recycled aggregates can be used as an alternative to natural aggregates.
► The soluble salts content can rise to 3.3% without reducing the quality of the work.
► The total sulphur content can rise to 3.9% without posing a sulphate leaching risk.