Effect of Na+ ion on the formation and hydration of ye'elimite containing Fe

The effect of Na2O-doped on the formation and hydration properties of ye'elimite containing Fe (C(4)A(2.8)F(0.2)$) was focused on this study. A combination of x-ray powder diffraction (XRD), infrared spectrum (IR), differential scanning calorimetry (DSC)-thermogravimetric (TG) analysis, and SEM-EDS were used to investigate the microstructure and morphology of C(4)A(2.8)F(0.2)$ with doping Na2O. Hydration kinetics tests were conducted to study the effect of Na2O on the C(4)A(2.8)F(0.2)$ by the isothermal calorimetry and the electrical conductivity. The results show that Na2O-doped promotes the phase transition of ye'elimite from orthogonal to cubic phase. The amount of Na+ ions substituted for Ca2+ ions reaches the limit doping Na2O with a dosage of 0.8 wt%, and the crystal structure of C(4)A(2.8)F(0.2)$ mineral tends to be stable. When the amount of Na2O is more than 0.8 wt%, the formation of C(4)A(2.8)F(0.2)$ is hindered and its content decreases. Besides, adding Na2O promotes the grain growth of the C(4)A(2.8)F(0.2)$, which doubles its average size, and makes the morphology of C(4)A(2.8)F(0.2)$ change from an egg-like shape to an irregular shape. In addition, the hydration process of C(4)A(2.8)F(0.2)$ doping with Na2O is accelerated, the induction period is significantly shortened or even disappeared, indicating Na2O facilitates the exothermic concentration of C(4)A(2.8)F(0.2)$ hydration. However, the addition of Na2O has no obvious effect on the total hydration heat release of C(4)A(2.8)F(0.2)$.

Automated summary

The effect of Na2O doping on the formation and hydration properties of ye'elimite containing Fe (C(4)A(2.8)F(0.2)$) was investigated in this study. The results showed that Na2O-doped promoted the phase transition of ye'elimite from orthogonal to cubic phase, and the crystal structure of C(4)A(2.8)F(0.2)$ tended to be stable. However, when the amount of Na2O exceeded a certain threshold, the formation of C(4)A(2.8)F(0.2)$ was hindered. In addition, adding Na2O accelerated the grain growth of C(4)A(2.8)F(0.2)$ and changed its morphology. Moreover, Na2O doping accelerated the hydration process and shortened the induction period of C(4)A(2.8)F(0.2)$.