Preparation and thermal performance of phase change material (PCM) foamed cement used for the roof

PCM foamed cement is to mix PCM with foamed cement. On the one hand, this new type of material can improve the thermal storage capacity of foamed cement, on the other hand, it could improve the thermal insulation performance of PCM when it completely melting or solidification. In this paper, the PCM foamed cement with different foaming rate were first prepared by physical method. Then, thermal conductivity of the PCM foamed cement was tested under different temperatures. Influence of foaming rate to the thermal conductivity was analyzed. Finally, the PCM foamed cement was placed on the external surface of the roofs of real buildings to form the PCM foamed cement roof (PCM FCR). In order to study its thermal performance, two cases were designed, case 1 was with high-reflectivity film on the external surface of the roof, case 2 was without high-reflectivity film. For the two cases, thermal performance of the PCM FCR was compared with foamed cement roof (FCR) and ordinary roof (OR). The results show that, PCM FCR and FCR can reduce the roof internal surface temperature by up to 2 °C and 1.1 °C in case 1, the values were 2.9 °C and 2.5 °C in case 2. The heat gain of PCM FCR and FCR can be reduced by 48.5% and 19.4% on average in case1. In case 2, the values were 59.0% and 51.2% on average. The PCM FCR performed best in reducing internal surface temperature and indoor heat gain among the three roofs.