Green Cementitious Composites Made with PCM-Recycled Brick Aggregates: Thermal Energy Storage Characterization and Modelling

This work reports the results of an extensive experimental campaign aimed at investigating the Thermal Energy Storage (TES) behavior of PCM Recycled Brick Aggregate (RBA) mortars. Test specimens for TES measurements were produced following a new spherical-shaped technique, patented as “DKK test” by the Institute of Construction and Building Materials of TU-Darmstadt. DKK was used for characterizing the various test samples made of plain cement paste plus porous RBAs, these latter filled with paraffinic PCM waxes. Dynamic DSC tests and conductivity measurements were also done for thermally investigating both components and composites. Moreover, the study proposes a novel numerical approach for determining the energy storage capacity of the investigated systems, setting the experimental benchmarks for validation. Particularly, the experimental results have been finally employed for calibrating an enthalpy-based model, at both macro- and meso-scale level, to evaluate the temperature-based thermal parameters like specific heat, conductivity, or more in a general sense, the energy storage capacity of these systems under transient heat conduction conditions. The results show very promising possibilities for using RBAs as carriers in green concrete applications.