Multiphysics analysis of effects of encapsulated phase change materials (PCMs) in cement mortars

There is growing interest in the use of phase change materials (PCMs) in the building industry, particularly in cementitious materials. However, the phenomenological interactions between PCMs and cement remain poorly understood and need to be clarified. In this study, mechanical tests were performed on several mortars modified by adding different amounts of PCM (5, 10, and 15 wt%). A series of experiments, including thermophysical analyses (thermogravimetric analysis and semi-adiabatic calorimetry), microstructural analyses (X-ray tomography, mercury intrusion porosimetry, scanning electron microscopy) and Fourier transform infrared spectroscopy provided phenomenological explanations of the evolution of the mechanical properties of these composites. It was determined that the degradation of the mechanical performance of the PCM-mortar composites was due to not only weak PCM inclusions but also a decrease in the degree of hydration of the composites, which induced a special evolution of the pore microstructure.