Autogenous and drying shrinkage of structural concretes incorporating recycled concrete aggregates from different sources

The main relevant difference between recycled concrete aggregates (RCAs) in comparison with the companion natural ones, is the presence of the Attached Mortar content which confers to the RCAs higher porosity and, consequently, higher water absorption capacity. In the last decades, several studies have been performed worldwide for unveiling the role of the employed RCAs on the resulting concrete mixture performances at both fresh and hardened states. On the other hand, the effects of RCA on the early-age and/or long-term concrete deformations (e.g., shrinkage) are still very limited. In this context, this article summarizes the results of a wide experimental campaign aimed at evaluating the influence of RCAs on the autogenous and drying shrinkage of normal (35 MPa) and high (60 MPa) strength recycled aggregate concrete (RAC) mixtures. A total of 10 mixtures were realized by considering the variation of both the original source and size of employed RCAs. The results showed a clear correlation between the intrinsic properties (i.e., Attached Mortar content) of the employed RCAs and the resulting concrete deformation. Moreover, although the drying shrinkage is higher for RAC mixtures, the presence of a more porous aggregates mitigates the observed autogenous shrinkage. Consequently, the overall total shrinkage result to be almost unaffected by the presence of the recycled particles.