Utilisation of unbound recycled aggregates from selected CDW in unpaved rural roads

Abstract

This article evaluates the behaviour and environmental impact of two recycled aggregates from selected construction and demolition waste (CDW) in field conditions. For this purpose, one experimental unpaved rural road with two sections was built in 2007. Sections were formed with an excellent subgrade (A-1-b) and two structural layers: the first section consisted of a base course and a surface built using a mixed recycled aggregate and a recycled concrete aggregate, respectively, and the second section consisted of crushed limestone aggregate as a reference. 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 of the fill layers was measured. The structural performance of the pavement was determined using a Falling Weight Deflectometer, and changes over time in the International Roughness Index and the bearing capacity were studied. The results show that recycled aggregates from selected CDW can be used as an alternative to natural aggregates in unpaved rural road construction without risk of environmental impact. According to technical specifications, the soluble salt content can rise to 1.3% without reducing the quality of this type of road. This study is important for increasing recycling rates and creating a market for mixed recycled aggregates in Mediterranean countries such as Spain, which has one of the lowest recycling rates in Europe.