不同水灰比下无水硫铝酸钙的水化反应

为澄清无水硫铝酸钙的水化反应机理，利用化学试剂CaCO3、Al2O3、CaSO4合成纯度达90%以上的无水硫铝酸钙(C4A3?)单矿物，研究其在水灰比为0.3、05、0.7条件下的水化反应，包括不同水化时间的水化产物及变化规律，用X射线衍射仪、综合热分析仪和扫描电子显微镜对水化产物进行分析.结果表明：水化产物为含不同摩尔结晶水的2种单硫型水化硫铝酸钙C4A?H12(AFm-12)和C4A?H14(AFm-14)以及无定形状态的铝凝胶(AH3)，整个水化过程未生成钙矾石(AFt)；随着水化时间的延长，C4A?H12(AFm-12)会逐渐转化为C4A?H14(AFm-14)；水化反应主要集中发生在3~12 h，后期C4A?H14晶体不断长大.
Calcium sulphoaluminate (C4A3?) with high purity (> 90%) was synthesized from CaCO3, Al2O3 and CaSO4, and the hydration of C4A3?, including hydration products and their evolution at different hydration time, was investigated at different water/solid ratios (mw/ms=0.3, 0.5, 0.7), aiming to clarify the hydration mechanism. The hydration products were examined by means of X-ray diffraction, differential scanning calorimetry-thermogravimetry and scanning electron microscope. There are two kinds of calcium monosulphoaluminate, namely, C4A?H14 and C4A?H12, and amorphous aluminium gel (AH3), while there is no ettringite (AFt) in the hydration products. C4A?H12 gradually converts to C4A?H14 as the extension of hydration duration. The hydration reaction mainly occurs between 3 and 12 hours after mixed with water. The crystals of C4A?H14 grow larger in later period.