Abstract
The integration of phase change materials (PCMs) into building materials offers a promising strategy for enhancing thermal energy storage and improving energy efficiency. This study investigates the incorporation of microencapsulated PCMs into recycled concrete aggregates (RCA) to develop a novel composite material for building applications. RCA derived from construction and demolition waste were impregnated with a paraffin-based PCM under vacuum conditions, then used as partial replacement for natural aggregates in cement mortar. The thermal and mechanical properties of the resulting composites were characterized using differential scanning calorimetry (DSC), thermal conductivity measurements, and compressive strength tests. Results showed that PCM-RCA composites exhibited latent heat capacities up to 45 J/g, with melting temperatures around 28°C suitable for building thermal regulation. Thermal conductivity decreased by up to 30% compared to control mortar, indicating enhanced insulation. Compressive strength reductions of 15-25% were observed, though values remained above 20 MPa for structural applications. A numerical model validated against experimental data predicted that integrating PCM-RCA into building envelopes could reduce indoor temperature fluctuations by up to 4°C and decrease annual heating/cooling energy demand by 12-18%. This work demonstrates the feasibility of valorizing waste concrete while improving building energy performance, contributing to circular economy principles.