Dry cost concretes produced with density-separated-crushed-CDW recycled aggregates

AbstractThe use of construction and demolition waste (CDW) in the production of dry cost concrete blocks harmonizes CDW recycled aggregates' characteristics with the different levels of mechanical requirements in use. At the same time, dry cost concretes are scarcely studied due to the difficulty to simulate industrial pressing energy in lab scale; however, that limitation can be partly overcome by using a lab scale compressive testing machine with elongation control, which also allows determining the mixtures' behaviour. The aim of this paper is to evaluate the fresh and hardened state of dry concrete produced with mixed CDW aggregates (with or without the use of density separation), by a lab-scale testing machine. Structural dry concrete can be obtained through the full substitution of the natural aggregates by density-separated-crushed-CDW recycled aggregates. The compressive strengths achieved are similar to those obtained by a reference dry concrete (produced with natural aggregates). The influence of the aggregates' characteristics and their dry mixes (cement; aggregates) was identified through a lab-scale compaction technique. The most important parameters to increase concrete compressive strength are the porosity reduction of recycled aggregates and granulometric optimization of dry mixes.