Crystal Chemistry of Hydrous Calcium Silicates: I, Substitution of Aluminum in Lattice of Tobermorite

摘要: Mixtures of 0.8 moles CaO per mole SiO2 plus Al2O3 were prepared from lime, kaolin, and tripoli (microcrystalline quartz); the amounts to varied give 0.2 20.7% by weight dry solids. After hydrothermal treatment (170° 175°C.), products examined differential thermal analysis X-ray diffraction. A homogeneous solid identified as mineral tobermorite (4CaO.5SiO2.5H2O) containing up 4 or 5% was obtained. Increasing amount in raw mixture above about resulted formation hydrogarnet 3CaO.Al2O3.SiO2.4H2O a second phase. Allowing for combined this solid, it indicated that slightly more substituted increased mixture. It is suggested Al3+ ions probably assume tetrahedral coordination when substituting Si4+ ions.