Mechanical and thermal properties of cement composite graphite for solar thermal storage materials

The comprehensive survey on an attractive thermal storage material consisted of aluminate cement and graphite is obtained in this paper. The effect of different water/cement (w/c) ratio and graphite content on compressive strength and thermal properties including thermal conductivity, volume heat capacity and thermal expansion coefficient of hardened aluminate cement pastes were investigated to pursue the optimum material design for solar parabolic trough power plant. It is observed that thermal conductivity and volume heat capacity were improved with the decrease of w/c and the increase of graphite content. The results show that w/c is a key factor affecting thermal properties of pastes and graphite even has some influence on the hydration process. After heat treatment at 350 degrees C for 6 h, compressive strength and thermal properties descended in a certain extent. XRD and FTIR were used to characterize the evolution of hydration products together. Furthermore, the properties obtained from the paper will lay the foundation for thermal storage materials of solar thermal power plants in the future. (C) 2012 Elsevier Ltd. All rights reserved.