Investigation on the formation of tobermorite in calcium silicate board and its influence factors under autoclaved curing

Compared with the traditional partition board, the superior properties of calcium silicate board are attributed to the generation of tobermorite, which can be influenced by many preparation conditions. The purpose of this study is to investigate the effect of Ca/Si ratio, and some others factors on the preparation and formation of tobermorite in calcium silicate board. The results reveal that the optimal cement content is 72%, at this time, Ca/Si ratio in calcium silicate board reaches 1.22. The tobermorite will gradually fade away when Ca/Si ratio continues to increase. XRD and mercury intrusion porosimetry after compression molding demonstrate that the molding pressure has mainly no effect on the hydration production and only has improvement on the structure of specimens. Due to the transformation of hydration production, autoclaved curing time and curing temperature should be controlled in specific range of 4-8 h and 190-195 °C, respectively. Additionally, the strength tests in different preparation factors present that the synthesis conditions confirmed in this paper are very promising to be applied in calcium silicate board.