Environmentally-friendly self-compacting concrete for rehabilitation of concrete structures

Self-compacting concrete technology can be particularly useful for rehabilitation of concrete structures due to its high fluidity, allowing to fill wide areas independently of their complicated shape and narrow section. Moreover, its cohesiveness guarantees adequate adhesion to the existing substrate as well. For this purpose, several self-compacting concretes were prepared by using different recycled aggregates coming from a suitable treatment of either rubble or concrete from building demolition as well as concrete from precasting plants. Self-compacting concretes were prepared without any filler addition. Other very-fine material required to achieve cohesiveness was supplied by the recycled aggregates themselves. Self-compacting concretes were characterized in the fresh state by means of slump-flow, V funnel, and L-box with horizontal steel bars tests. They were then characterized in the hardened state by means of compression and splitting tension tests, in addition to drying shrinkage measurements. However, the shrinkage of the self-compacting concrete, expected to be higher because of the lower inert/cement, could cause differential strain with respect to the substantially stable old concrete substrate. This risk can be avoided provided that right adjustments of the self-compacting concrete mixture are adopted, as shrinkage-reducing admixture and/or fibres are added.