Concrete design towards complete recycling

Abstract

Concrete which is suitable for complete recycling will allow repeated recycling, as is the case for steel and aluminum. Since these concretes are composed only of cementitious materials, and the powders generated during the production of recycled aggregate can be reprocessed as cement resources, this permits repeated recycling. This enables concrete to be recycled in a fully closed system, thus reducing the carbon dioxide emitted during the calcining of cement. To permit recovery of high-quality recycled aggregates from demolished concrete, the concrete should be made with coated virgin aggregate. The coating agent will have the effect of decreasing adhesive strength between aggregate and paste, but not to the extent that the mechanical properties of the concrete will significantly deteriorate. The fundamental properties of the aggregate-recovery-type recycling-oriented concrete and the properties of recycled aggregates recovered from concrete were investigated experimentally. The results showed that demolished aggregate-recovery-type recycling-oriented concrete successfully yielded recycled aggregate and the quality of the recovered aggregate was improved by the use of coating materials. Accordingly, the aggregate-recovery-type recycling-oriented concrete can be designed to serve as both a cement resource and a recycled aggregate.