Experimental Characterization of Sustainable Cementitious Composites: Thermal Energy Storage with Recycled Wood Aggregates and Bio-based Phase Change Materials

Abstract This paper reports the results of an experimental program on sustainable cementitious composites made with recycled wood aggregates (RWAs) filled with bio-based phase change materials (PCMs). The experimental program focused on fabricating PCM–RWA-labeled energy wood aggregates (i.e., “NRG-WOOD”). Three mortar types of ordinary Portland cement (OPC), Wood-Mortar, and NRG-WOOD Mortar were evaluated for their thermal performance which involved hydration tests to monitor early-stage temperature evolution, dynamic sphere calorimetry (DKK) tests for latent heat storage assessment, and calorimetry to determine specific heat capacities. Durability was assessed through capillary absorption tests, while the experimental campaign also included mechanical tests to investigate the impact of PCM within the recycled wood aggregates, on the resulting mortar strengths under both compression and bending. Promising results have been obtained for the NRG-WOOD mortars, showing a significantly reduced water absorption by approximately 63% lower than conventional OPC mortars and a high thermal energy storage capacity at an acceptable strength reduction of approximately 30% in compressive strength and a 24% reduction in flexural strength compared to OPC due to PCM addition. This study presents an innovative approach to PCM integration in RWAs, optimizing both thermal storage and durability. Compared to conventional mortars, the proposed NRG-WOOD mortar demonstrates a novel solution for sustainable and energy efficient construction by significantly enhancing moisture resistance while maintaining acceptable mechanical performance.