Elastoplastic-damaged meso-scale modelling of concrete with recycled aggregates

The use of recycled concrete aggregates is very attractive from the point of view of reducing concrete production costs and of sustainability. A peculiar origin of such aggregates is that of demolitions of pre-existing concrete buildings. Scope of this work is to analyse the challenging aspects of recycled aggregates modelling in concrete mixtures and to define a procedure to cope with them. Particularly, numerical analyses dealing with the mechanical behaviour of concrete mixtures made of natural and recycled aggregates are here performed at the meso-scale level, distinguishing between concrete paste and aggregates themselves. Some compelling issues for the modelling phase are addressed, i.e.: i) the correct reproduction of recycled aggregates within the concrete samples, which involves both the acquisition of the external geometry of the aggregates and their random disposition in the sample, ii) the characterization of the mechanical constitutive law of the composite. An elastic-plastic-damaged formulation is adopted for representing the constitutive behaviour of mortar and cement matrix; the procedure is calibrated and validated so proving its predictability features when describing damage triggering and spreading within concrete samples subjected to compressive loads.