The Influence of Mayenite Employed as a Functional Component on Hydration Properties of Ordinary Portland Cement

Influence of C(12)A(7) (12CaO·7Al(2)O(3)) as a functional component on hydration properties of Ordinary Portland Cement is studied using isothermal microcalorimetric technique, X-ray diffraction analysis, and thermodynamic calculation. Meanwhile, hydrate assemblages are simulated by hydrothermal software. C(2)AH(8) (2CaO·Al(2)O(3)·8H(2)O) is generated as a transition phase during the hydration of pure C(12)A(7), while formation of CAH(10) (CaO·Al(2)O(3)·10H(2)O) is uncertain. Heat-releasing behavior of Ordinary Portland Cement (OPC) could be noticeably affected by C(12)A(7), especially for the duration of interaction at boundary stage reduces with C(12)A(7) replacement. Correspondingly, all hydration kinetic parameters first increase and then diminish with C(12)A(7) replacement. Simulation results manifest in the main hydration products of OPC being ettringite, C-S-H (Calcium-Silicate-Hydrate) gel, portlandite and brucite. Increasing C(12)A(7) replacement accelerates the consumption rates of gypsum and calcite that are typically included in OPC, and thus the ettringite content is changed and carbonate phases will be produced. Therefore, the microstructure properties of hydrated products of OPC are affected and the compressive strength is influenced. These predications are in good agreement with experimental findings. C(12)A(7) can be used as a functional component to adjust the consumption rate of suphates in OPC, and also components of carbonate phases can be modified in hydrate assemblage.