Physico-mechanical properties of multi-recycled self-compacting concrete prepared with precast concrete rejects

Abstract

The precast concrete industry produces a substantial quantity of waste due to quality non-conformances. Rather than deposit them in landfill, these products can be crushed, generating recycled aggregate, a by-product that may be reintroduced in the manufacturing process. But, what would happen if the recycled concrete pieces were rejected again? Is it possible to recycle the recycle concrete? The purpose of this paper is to study the possibility of multi-recycling precast concrete, in one of its most popular precast industry types: self-compacting concrete. In this study three recycled cycles were carried out, all of them using 100% recycled aggregate. The results showed that the new concretes with recycled and multi-recycled coarse aggregates from precast concrete rejects performed equally well, even slightly higher in compressive strength compared with control concrete; the increases at 28 days were 7.7%, 10.9% and 13.8% for the first, second and third recycling cycle, respectively. The performances of recycled concretes were better than reported in previous research, which is owing to the high quality of precast concrete recycled aggregates. The precast concrete industry can be more eco-friendly with its new self-compacting concrete products, produced with aggregates recycled from quality test failure or old pieces after their service phase. With this, the precast concrete industry will close the recycling concrete circle, decreasing its environmental impact and incurring potential cost savings. © 2017 Elsevier Ltd