Analytical tool for assessment of the rheological behavior of recycled aggregate concrete

This study proposes an analytical tool aimed at estimating the rheological behavior at the fresh state of concretes produced with Recycled Concrete Aggregates (RCAs). The proposed tool is based on two series of experimental campaigns conceived for emphasizing the role of the RCAs inclusions by measuring the yield stress, plastic viscosity and slump values. The model is calibrated on the results obtained by the first group of mixtures considering the water-to-cement ratio and RCAs' content as primary variables. A validation and extension of the model is proposed with a second experimental campaign in which the mixture proportioning parameters, such as concrete strength class, size and source of RCAs and amount of superplasticizer, are considered. The proposed approach highlights the key role of the specific features of the RCAs, namely shape index and attached mortar, on the rheological behavior of recycled aggregate concretes.