Post-processing of recycled concrete aggregates (RCA) and their complete utilisation: production, characterisation & performance

This study examines the characteristics of various size fractions derived from crushed end-of life concrete, with the objective of integrating them fully into sustainable new concrete. A two stage approach was used to prepare recycled concrete aggregate (RCA); with crushing to weaken adhered mortar followed by autogenous cleaning via tumbling to remove it. The recycled concrete aggregate (RCA) was assessed in terms of size, specific gravity, adhered mortar content, and water absorption capacity. The specific gravity of the RCAs decreased with decreasing aggregate size as the adhered mortar content increased, in turn leading to higher water absorption capacity. This approach yielded superior RCA compared to crushing alone, and appeared to partially mitigate the presence of highly porous, micro-cracked superficial layers. The new recycled aggregate concrete (RACs) mixtures were assessed in terms of workability and compressive strength development. Under these specific laboratory conditions, the resulting concrete mixtures exhibited early-to-mid-term mechanical properties broadly comparable to baseline natural aggregate concrete. This study can be regarded as contributing to better understanding of the reuse potential of recycled concrete aggregates to prepare new concrete.