Thermodynamic data calculation for iron phases in sulfoaluminate cementitious materials prepared using solid wastes

The preparation of sulfoaluminate cementitious materials (SCM) is a promising way to massively utilize solid wastes. Iron phases are significant in SCM system but the thermodynamic data of some key minerals, such as 6CaO center dot Al2O3 center dot 2Fe(2)O(3) (C(6)AF(2)) and 6CaO center dot 2Al(2)O(3)center dot Fe2O3 (C(6)A(2)F), are missing, which greatly hinders the SCM optimization in a theoretical way. This work, for the first time, calculated the standard formation enthalpy, Gibbs free energy of formation, entropy and molar heat capacity for C(6)AF(2) and C(6)A(2)F and lowered the errors to the least with the reference of C(4)AF data in the literature. By building the function diagram of Gibbs free energy changes with temperature for the basic iron phase formation reactions with the obtained thermodynamic data, it is proved that the formation likeliness of C(6)AF(2) is higher than that of C(6)A(2)F, as is accordant to the literatures and verifies the correctness of obtained data. This work provides a good theoretical foundation to optimize SCM mineral system and to study relevant mechanism deeply. (C) 2019 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.