Experimental and numerical study of the incorporation of spent coffee grounds and phase change materials in hollow bricks manufactured by 3D printing

As part of a sustainable development and circular economy approach, this study proposes the manufacture of ecological bricks by combining extrusion 3D printing, the recovery of spent coffee grounds (SCG) and the incorporation of phase change materials (PCM) into bricks based on local clay. Following a physicochemical characterization of the materials, thermo-physical tests were used to feed a numerical model based on the finite volume method to analyze the thermal behavior of the bricks in various configurations. The results show that the addition of 10% SCG reduces the thermal decrement factor by 25% (compared 38% without SCG), while the optimal impregnating of PCM (with the appropriate melting temperature, latent heat, mass and specific location and distribution in the brick) significantly improves thermal regulation, phase shift and summer comfort. The external thermal amplitude plays a key role in activating and choosing the suitable the PCM. These bricks represent a promising advancement for sustainable buildings, by reducing waste and energy consumption while guaranteeing improved thermal comfort.