Recycled aggregate in road construction following the Spanish General Technical Specifications for Roads and Bridge Works (PG-3): a case study

This research characterizes four samples of recycled aggregate for their potential use in road construction projects in consonance with the Spanish General Technical Specifications for Roads and Bridge Works (PG-3). Although some fractions were of sufficient quality for the construction of embankments, backfills, and quarry-run fills, they were ultimately found to be unsuitable for the construction of underground drainage, granular structural layers, soil stabilization and concrete pavements. They were negatively evaluated because of their particle size distribution and sulfate content. Nevertheless, the quality of this recycled aggregate could be substantially improved by manually removing the gypsum before the crushing process at the plant or by selecting the material with greater care at the beginning of the process. Finally, we suggest that Construction and Demolition (C&D) waste plant managers should modify the manufacturing process to obtain a suitable particle size distribution in accordance with PG-3 requirements and the projected use of the aggregate.