Experimental exploration of incorporating form-stable hydrate salt phase change materials into cement mortar for thermal energy storage

In this study, the thermal energy storage cement-based composites were fabricated by integrating cement mortar with the form-stable hydrate salt PCMs based on binary eutectic hydrate salt/expanded graphite oxide (EHS/EGO) and EHS/poly (acrylamide-co-acrylic acid) copolymer (EHS/P(AA-AA)). The form-stable hydrate salt PCMs were incorporated in cement-based composites at 5%, 10%, 15% and 20%, by weight of sand. It is found that the mechanical strengths of the thermal energy storage cement-based composites decrease with the increasing form-stable hydrate salt PCMs content, however, they can still be able to use as building envelope materials. Furthermore, Scanning Electron Microscopy (SEM) was used to investigate the compatibilities of EHS/EGO and EHS/P(AA-AA) with cement mortar. The pore size distribution collected from mercury intrusion porosimeter (MIP) results also has been analyzed, which is associated with mechanical strength and thermal conductivity. Besides, thermal performance test demonstrates that the cement mortars containing the form-stable hydrate salt PCMs have good endothermic and exothermic characteristics and play a role in adjusting the peak value of indoor temperature.