Microencapsulated phase change material in 3D-printable mortars

• Adding MEPCM increased the printability, yield stress, and viscosity of mortars. • MEPCM can avoid the further need for additives like viscosity modifier agents. • A printed wall with 80 % sand replaced by MEPCM showed a 40.4 % energy reduction. • MEPCMs showed stability and resistance to the alkaline cementitious environment. • The integration of MEPCM resulted in a retardation effect on the setting time. The present study investigates the potential of replacing sand with microencapsulated phase change materials (MEPCM) in 3D-printable mortar to provide a promising way to improve thermal performance in 3D-printed buildings. Adding MEPCM significantly enhanced the rheological properties and early hardening evolution of cementitious mortar for 3D printing applications without the need for viscosity modifier agents. In hardened mortars, microstructural analysis and thermal cycling experiments confirmed that MEPCM remained intact and stable within the cementitious environment. The thermal properties of the treated mortars, including latent heat and thermal conductivity, were improved for energy-saving applications. Despite this, the compressive strength of the mortars dropped considerably by increasing the concentration of MEPCM while a strength of above 20 MPa was maintained. Simulation results from 3D Finite Element Method (FEM) and 1D reduced order model (ROM) closely matched the experimental data from printed walls in a thermal setup, validating the use of 1D ROM simulations for long-term predictions. In a case study, a printed wall where MEPCM replaced 80 % of the sand showed a ∼40 % reduction in energy consumption compared to mortar without MEPCM under real weather conditions.