Effect of ${\mathrm{C}}_3\mathrm{A}$ on Performance of Thaumasite Form of Sulfate Attack of Silica Minerals

The effect of tricalcium aluminate (${\mathrm{C}}_3\mathrm{A}$) on the erosion degree and products of silica minerals under the thaumasite form of sulfate attack condition was studied using X-ray diffraction (XRD), a scanning electron microscope (SEM), and an energy dispersive spectrometer (EDS). The results show that ${\mathrm{C}}_3\mathrm{A}$ accelerated the formation rate of thaumasite, and the improvement degree depended upon ${\mathrm{C}}_3\mathrm{A}$ dosage. Crystal structures presented that the erosion products were thaumasite form solid solution after attack, and the value $a$ decreased with increasing of ${\mathrm{C}}_3\mathrm{A}$ content, but value $c$ had the opposite result. The morphology of the solid solution indicated that the crystal size became smaller as the ${\mathrm{C}}_3\mathrm{A}$ dosage increased.