Effect of strontium dioxide on the crystal structure and properties of tricalcium silicate

Tricalcium silicate (C₃S) doped with strontium dioxide was sintered at high temperature of 1600°C by solid reaction. The crystal structure and properties of C₃S doped with strontium dioxide were investigated by means of chemical analysis, X-ray diffraction analysis, infrared analysis and hydration heat analysis. The experimental results show that pure C₃S crystal has a triclinic crystalline form at room temperature. When doped strontium dioxide concentration is no more than 0·025 M, alite crystal is the same as the pure C₃S crystalline form, whereas when doped strontium dioxide concentration is in the range 0·025–0·075 M, alite crystal is in monoclinic crystalline form. A small amount of strontium dioxide has the effect of decreasing the free lime content and promoting the formation of alite. Infrared analysis indicates that the addition of strontium dioxide can improve the crystal symmetry of alite. The hydration heat analysis shows that the addition of strontium dioxide can enhance hydration activity of alite and accelerate the hydration process.