Experimental study of geopolymer mortar with incorporated PCM

Incorporation of phase change material (PCM) in building materials has been an important research topic in recent years. The use of PCM intends to increase the thermal inertia of buildings and reduce the consumption of energy for cooling and heating. This paper studies experimentally the mechanical and thermal properties of geopolymer mortar synthesized with low calcium fly ash and different amount of PCM. First the effect of incorporated PCM on the unit weight and compressive strength of geopolymer mortar was evaluated. Then scanning electron microscopy (SEM) imaging was performed to identify the change of micro structure of the geopolymer mortar after incorporation of PCM. The thermal properties of the geopolymer mortar containing different amount of PCM were also characterized using differential scanning calorimetry (DSC) analysis. Finally model tests were performed using small cubicles built with geopolymer mortar slabs containing different amount of PCM to evaluate the effectiveness of geopolymer mortar wall with incorporated PCM in controlling the heat flow and internal temperature. The results indicate that both the unit weight and compressive strength of the geopolymer mortar decrease slightly after PCM is incorporated, mainly due to the small unit weight and low strength and stiffness of the PCM. However, the compressive strength of geopolymer mortar containing up to 20% PCM is still sufficiently high for applications in buildings. The results also show that the incorporation of PCM leads to substantial increase of heat capacity and decrease of thermal conductivity of the geopolymer mortar and is very effective in decreasing the temperature inside the cubicles. Therefore, the geopolymer mortar with incorporated PCM can be used as building walls to effectively increase the thermal inertia of buildings and reduce the consumption of energy for cooling and heating.